International Student Conference “Science and Progress” · PDF fileInternational Student Conference “Science and Progress ... Precipitation was carried on the surface of the

CONFERENCE ABSTRACTSInternational Student Conference

“Science and Progress”

St. Petersburg – PeterhofSeptember, 30-October, 4

2013

German-Russian Interdisciplinary Science Center

3

Organizing Committee

Prof. E. Rühl, Coordinator of G-RISC, FU BerlinProf. A.M. Shikin, Coordinator of G-RISC, SPSUProf. S.F. Bureiko, Senior Vice-Dean of Faculty of Physics, SPSUE. Serova, G-RISC office in SPSU, T. Zalialiutdinov, G-RISC office in SPSUM. Rusinova, G-RISC office in SPSU

Program Committee

Dr. A.A. Manshina, Faculty of Chemistry, SPSU (Section A - Chemistry)Prof. V.N. Troyan, Faculty of Physics, SPSU (Section B – Geo- and Astrophysics)Prof. V. Reitmann, Faculty of Mathematics and Mechanics, SPSU (Section C – Mathematics and Mechanics)Prof. A.P. Baraban, Faculty of Physics, SPSU (Section D – Solid State Physics)Dr. A.S. Chirtsov, Faculty of Physics, SPSU (Section E – Applied Physics)Prof. N.A. Timofeev, Faculty of Physics, SPSU (Section F – Optics and Spectroscopy)Prof. Yu.M. Pismak, Faculty of Physics, SPSU (Section G – Theoretical, Mathematical and Computational Physics)Prof. N.V. Tsvetkov, Faculty of Physics, SPSU (Section H - Biophysics)Prof. V.I. Chizhik, Faculty of Physics, SPSU (Section I – Resonance Phenomena in Condensed Matter)

Contacts

Faculty of Physics, Saint-Petersburg State UniversityUlyanovskaya ul. 1, Peterhof, St. Petersburg, Russia 198504 Tel. +7 (812) 428-46-56, Fax. +7 (812) 428-46-55 E-mail: [email protected] Website: www.g-risc.org

A. Chemistry

6

Studying the influence of reducing agent in the process of laser-induced deposition of copper from solution

Araslanova Svetlana, Khairullina Evgeniia, Safonov [email protected]

Scientific supervisor: Dr. Kochemirovsky V.A., Department of Laser Chemistry and Laser Materials Science, Faculty of Chemistry, Saint-Petersburg State University

The interest in LCLD is due to the prospects of application of this method in microelectronics and technology, as it allows maskless manufacture of metallic structures on the surface of dielectrics [1]. Focused laser beam scanning of the surface of a dielectric placed into a special solution results in local initiation of chemical reduction to give metallic copper according to equation (1)

( 2) 02 22 4 2 2n nCuL HCHO OH Cu L H HCOO H O− − − − −+ + → + + + + (1)

where L is an organic complexing agent (sodium potassium tartrate); formaldehyde or sorbitol act as the reducing agent. The copper salt used is most often sulfate or chloride.

In the chemical copper plating as a reducing agent commonly used formalde-hyde. In LCLD in its application fails to create a structure with high-quality cop-per topology and low electrical resistance. In previous research it was shown that during the deposition using Nd: YAG laser with a wavelength of 532 nm sorbitol is perspective reducing agent in LCLD [2]. Therefore, we investigated the effect of different polyols as reducing agents on the results of the deposition of copper. Precipitation was carried on the surface of the glass ceramics «Sitall 50-1» which is applied in microelectronics for the manufacture of microwave equipment.

The main goal of work is the deposition of continuous metal tracks with high-quality topology and high electrical conductivity from solutions containing one - and polyatomic alcohols: ethanol, 1,2-propylene glycol, glycerol, xylitol, sorbitol using Nd:YAG laser with a wavelength of 457 nm. The result of this work it was found that at the same power of laser radiation (600 mW) the minimum value of resistance and the low threshold for initiation reactions were obtained by deposi-tion from a solution containing sorbitol.

References1. Kochemirovsky V.A., Menchikov L.G., Safonov S.V., Bal'makov M.D., Tumkin I.I., Tver'yanovich Yu.S. // Russian Chemical Reviews, 80 (9) 869-882, (2011)2. Kochemirovsky V.A., Logunov L.S., Safonov S.V., Tumkin I.I., Tver'yanovich Yu.S., Menchikov L.G. // Applied Surface Science, 259 pp. 5-58, (2012)

7

Synthesis, characterization and photophysical properties of luminescent bimetallic Au(I) complexes with 9,10-

bis(diphenylphosphino)anthracene

Belyaev [email protected]

Scientific supervisor: Dr. Krupenya D.V., Department of General and Inorganic Chemistry, Faculty of Chemistry, Saint-Petersburg State University

A series of novel luminescent gold(I) alkynyl-phosphine complexes of general formula [Au2{Ph2P(An)PPh2}(C2R)2], where An – 9,10-antracylen was prepared by the self-assembly reactions, starting from simple precursors. The compounds were obtained according to Scheme 1 and characterized by NMR 1H and 31P spec-troscopy and ESI-MS measurements. The solid state structures of complexes (1), (2) and (3) have been elucidated by X-ray crystallography.

Scheme 1.In this work much attention were paid to studying photophysical properties of

starting 9,10-bis (diphenylphosphino)anthracene and resulting complexes. It was found that the complexes exhibit dualband luminescence in solutions and the luminescence depends on excitation wavelength.

The work was carried out using scientific equipment of the Center of Shared Usage "The analytical center of nano- and biotechnologies of SPbSPU" with finan-cial support of the Ministry of Education and Science of the Russian Federation and Centres of St.Petersburg State University: X-ray Diffraction Сenter; Сenter for Magnetic Resonance; Center for optical and laser materials research; Center for chemical analysis and materials research. Financial support from Saint-Petersburg State University research grant 12.37.132.2011 and Russian Foundation for Basic Research (grants 11-03-00974-а and 11-03-92010) is gratefully acknowledged.

PPh2

PPh2

RAu2 +

PPh2

Ph2P

Au

R

Au

RR = HO

OH

OH

N N

1 2 3

4 5 6

DCM

30 minn

8

Optimization of sample preparation methods nails for digital spectrographic trace element analysis

Budalyaeva [email protected]

Scientific supervisors: Prof. Dr. Drobishev A.I., Savinov S.S., Department of Chemistry, Saint-Petersburg State University

Modern methods of system diagnostics, treatment and prevention of diseases based on the analysis of macro-and trace element composition of the biological substrates of man. Shortages of essential elements, or excess of both essential and toxic trace elements increase causes a deviation in the health of the body. The main sources of trace elements in the human body are food, water and air. In this regard, at present there is a problem of anthropogenic environmental pollution because, for example, it is known that in the immediate vicinity of many industrial zones are formed with a high content of lead, cobalt, cadmium, nickel and other toxic trace falling within body and pose a threat to the health and even the life of a person.

Currently, there are a number of objects of analysis used for the diagnosis of, for example, plasma, serum, saliva, urine, hair, skin and nails. In comparison to other biological samples, there are many advantages in utilizing nails as a biomarker of toxic element exposure. The relative levels of elements in nails are indicative of physiological changes, body storage of elements, the proportionate levels of ele-ments in nails and other tissues, as the best indicator or biomarker of a particular element, implication of health status, and status and duration of exposure. For these reasons, an object of research in this study were selected sample nails.

The paper contains the method developed mineralization samples nails, with all procedures carried out. Determination of trace elements was done by the method of atomic emission spectrographic analysis of digital liquid sample, which was previously developed in our laboratory. Total analysis time is not more than 3 hours from sample preparation, and ending the data processing of a large number of content elements (for example, Ag, Cd, Pb, Cu, Cr, Mn et al.).

9

Solubility and liquid-liquid equilibrium in quaternary reacting system ethanol - ethyl acetate - acetic acid -

water at 30 °C and 40 °C

Golikova Alexandra, Toikka Maria, Trofimova [email protected]

Scientific supervisor: Dr. Toikka M.A., Department of Chemical Thermodynamics and Kinetics, Faculty of Chemistry, Saint-Petersburg State University

The studying of combined (coupled) processes is of the great interest for the development of science at the moment. Experimental data of phase and chemical equilibrium are necessary for elaboration of methods of substances separation and purifying. Utilization of combined processes (phase and chemical equilibrium) in industry permits significantly increase the output of products, provide high selectiv-ity, and to simplify technological schemes [1]. Reaction and mass transfer processes are very importance for synthesis of clean fuels. Also the studying of liquid phase splitting systems assumes formation of large experimental database.

This work is deal with the thermodynamic research of properties of quaternary system: ethanol, ethyl acetate, acetic acid and water. This is one of such systems with almost full experimental data nowadays. Complete thermodynamic descrip-tion of considered system requires the studying of binary and ternary subsystems. Solubility and liquid-liquid equilibrium in quaternary system was completely studied at 30 ˚C [2] and 40 ˚C.

This research was supported by Committee on Science and Higher Education of St. Petersburg for young scientists, young PhD, industry and academic institutions located in the territory of St. Petersburg (2013, Toikka Maria).

References1. Zharov V.T. Voprosy termodynamiki geterogennyh system I teorii poverhnos-tnykh yavlenij (Questions about thermodynamics of heterogeneous systems and surface phenomenon theory) V. 2, 35-53 (1973).2. Trofimova M., Toikka M., Toikka A.J. // Fluid Phase Equilibria. V. 313, 46-51 (2012).

10

Optimization of the solution to obtain a microthermocouple by the method of LCLD

Gorshkova Ksenia, Logunov Lev, Safonov [email protected]

Scientific supervisor: Kochemirovsty V.A., Faculty of Chemistry, Saint-Petersburg State University

Laser-induced deposition of metal from solution (LCLD) – unique method of deposition microconductors, which are widely used in microelectronics and sensor technology.

The aim of the research is to develop an optimal solution composition for deposition copper and nickel structures using LCLD. This allows us to create a “microthermocouple” Ni-Cu on the surface of glass-ceramics for the following study of the temperature gradient near the focus of a laser beam. The results of deposition are shown in the Table1.

Solution composition

Optical

microscopy, 40-х

Scanning electron microscopy

Distribution of metal on a cross-

section of deposited structure

Copper structure

С(CuCl2) = 0.01 M С(C4H4O6KNa)=0.03 М

С(NaOH) = 0.1 M С(C5H12О 5) = 0.075 M

The active component of the electric resistance 1.45 Om∙cm

Nickel structure

С(NiSO4) = 0.08 М С(CH3COOH)= 0.12 М

С(NaOH) = 0.12 М С(С2Н5NO2) = 0.4 M

C(NaH2PO2) = 0.24 MThe active component of the electric

resistance 9.8 Om∙cm

Table 1. The results of laser-induced deposition of metals.References

1. Kochemirovsky V.A., Logunov L.S., Safonov S.V., Tumkin I.I., Tver’yanovich Yu.S, Menchikov L.G. // Applied Surface Science, 259 (2012) pp. 55– 58.

11

Surface enhanced raman scattering of brilliant green on Au -Ag-C nanoparticles

Kireev Alexey, Olshin [email protected]

Scientific supervisor: Dr. Povolotskiy A.V., Department of Laser Chemistry, Faculty of Chemistry, Saint-Petersburg State University

The most striking example of metal NPs’ properties is the Surface-enhanced Raman scattering (SERS). SERS spectroscopy has experienced fast progress in the last few decades since it was recognized as a powerful tool in many research areas such as chemistry, surface science, spectroscopy, biomedicine, and toxin detection. Therefore, there is significant interest in designing and optimizing of SERS-oriented substrates.

This work deals with study surface enhanced Raman scattering (SERS) of brilliant green (BG) on Au-Ag-C nanoparticles. Metallic silver-gold nanoparticles encapsulated into carbon were synthesized via laser-induced chemical liquid phase deposition [1]. The obtained carbon-silver-gold nanostructures were characterized by high specific surface area and demonstrated high sensitivity as a material for surface-enhanced Raman scattering and adsorption properties. The drops of solu-tions BG were spilled on the substrate surface with NPs deposited at various laser exposure times: 1, 5, 10, and 15 min. The most efficient surface enhanced Raman scattering was found for the sample with NPs deposited at 10 min laser irradia-tion. Also, surface enhanced Raman scattering (SERS) of different concentrations of brilliant green (BG) on Ag nanoparticles (AgNPs) has been investigated. The observed detection limit of BG concentration of about 10-7 M.

The obtained C-Au-Ag NPs demonstrate high SERS activity that makes them efficient materials for quantitative monitoring of low concentrations of hazardous chemical substances.

References1. Povolotskiy A., Povolotckaia A., Petrov Y., Manshina A., Tunik S.// Appl. Phys. Lett. 103, 113102 (2013).

12

Homo- and bridging heterometallic complexes of rhenium with transition metals: synthesis and structure

characterization

Kisel [email protected]

Scientific supervisors: Koshevoy I.O., Grachova E.V., Department of Chemistry, Saint-Petersburg State University

Heteroleptic carbonyl rhenium complexes attract the growing interest due to them bright photophysical properties. Here in we report an overview of the preparation of some homo- and bridging heterometallic complexes of rhenium with a few transition metals. The compounds of interest have been prepared according to the following scheme:

Fig. 1. Reaction condition: autoclave, 200 °С, 40 bar, chlorobenzene, 20 hours (for 2 and 6); room temperature, darkness, acetone, 20 hours (for 3 and 5); reflux-ing under nitrogen, dichloromethane, overnight (for 4).

The structures of complexes 2-6 were characterized by 1H, 31P NMR spectros-copy (in a solution) and by X-ray diffraction analysis (in a solid).

It has been found that the complex 3 fluoresces in the green region of the spectrum, while the remaining compounds fluoresce in the yellow region of the spectrum when excited by light with λex = 410 nm.

The authors greatly appreciate the financial support of St. Petersburg State University research grants 12.37.132.2011, 12.39.1048.2012 and Russian Foundation for Basic Research grant 13-04-40342.

Cl

Re

CO

CO

CO

Re

CO

OC CO

Re

OC

COOC

C N Au N C

Re

CO

CO

CO

P

P

P

P

ReOC

CO

OC

ReOC

CO

COP

P

Re COOC

OC

NN PtCN

Re

OC CO

CO

Re

COOC

OC

C N

P = PPh2

N

N

N

N

N

N

N

NN

N N

N

N N

N

NN

N

N

N=

N

N

2

3

4

5

6

1

13

Microwave synthesis of ultrafine alumina powder

Mitrofanov [email protected]

Scientific supervisor: Dr. Selutin A.A., Department of General and Inorganic Chemistry, Faculty of Chemistry, Saint-Petersburg State University

Recently, much attention is paid to obtaining materials in nanostate with high specific surface area. On the specific surface depend on absorption capacity of adsorbents, the efficiency of solid catalysts, the properties of the filter materials. But most modern techniques such as cryochemical , mechano-chemical, plasma-chemical, hydrothermal synthesis require a strong flow of energy from an external source, as these methods lead to the production of nanoparticles in non-equilibrium metastable state.

Our task was to find a simple approach to getting a new sorbent based on aluminum oxide.

Sorbents based on alumina can be an alternative to the currently used for separat-ing and concentrating substances silica sorbents. Alumina is available mechanically strong and stable sorbent, which has found wide application in organic analysis.

The synthesis method is based on the reaction of the metal nitrate with urea in aqueous solution during the heat treatment by microwave radiation. Synthesis of alumina was conducted by utilizing as the solvent is not just water, but a mixture of ethyl alcohol and water in a volume ratio of 1:1. Mass calculated and weighted source of aluminum nitrate and urea are dissolved in water or mixtures of water and alcohol. The resulting solutions were placed in a household microwave oven. Heat treatment was carried out with solutions of microwave power of 700 watts.

We have developed a method for producing alumina using microwave heat treatment of aqueous and alcoholic solutions containing aluminum nitrate and urea. We show that the aqueous-alcoholic solution synthesis alumina is faster than water, and synthesis of solutions with a high content of aluminum nitrate source is slower.

XRD data suggest getting one phase of alumina with corundum structure.By low-temperature nitrogen adsorption of oxides defined surface area. The

specific surface of the oxide depends on the initial concentration of the starting aluminum nitrate. The specific surface of the oxide higher than in the synthesis of the more diluted solution and from an aqueous-alcoholic solution.

The calculated value of the specific surface area average diameter of particles (6-7 nm) showed obtaining nanopowders alumina.

14

Composition influence on the lithium-phosphate glasses structure

Olshin Pavel, Kireev [email protected]

Scientific supervisor: Dr. Povolotskiy A.A., Department of Laser Chemistry and Laser Materials, Faculty of Chemistry, Saint-Petersburg State University

Phosphorus oxide is an important glass-forming component which can be useful in the glass synthesis. Content of P2O5 by 40 to 100 % restricts the glass-forming limit of the phosphorus oxide – metal oxide mixtures. Glasses consist only of P2O5 less 60% has practical applications because of great hygroscopicity. The glass-forming composition limit is close to methaphosphate one, so the structure of the obtained glasses is defined by methaphosphate one. The glass isn’t the equilibrium state of matter so, the other structure units can form.

The aim of this work is an investigation of the lithium-phosphorus glasses ((Li2O)x-(P2O5)(1-x), x=0.4, 0.43, 0.49, 0.52, 0.55) structure by Raman spectroscopy. Glasses had been synthesized according to the reaction equation:

(NH4)H2PO4 + Li2CO3 = Li2O-P2O5 + NH3↑ + H2O↑ + CO2↑Atomic absorption spectroscopy and photometric analysis was used for precise

definition of the glass composition. Raman spectra were received using the spec-trometer Bruker Senterra, excited laser wavelength was 532 nm.

Atomic absorption spectroscopy results show decreasing of the more volatile component – phosphorus oxide amount. A Raman spectrum demonstrates the distortion of the some Raman lines. Maximum position of the one peak near 1150 cm-1 is shifted towards the low-frequency region with increasing of Li2O content. The dependence of the peak position on glass composition has been demonstrated. Approximate analysis of the local area inside lithium-phosphate glasses can be held by Raman spectroscopy.

Raman spectra were obtained at the Center for Optical and Laser Materials Research of Saint-Petersburg State University. Atomic absorption spectroscopy and photometric analysis were performed at the Center for chemical analysis and materials research of Saint-Petersburg State University.

15

Optical digital spectrography with arc discharge in microelement analysis of liquid samples

Savinov [email protected]

Scientific supervisor: Prof. Drobyshev A.I., Department of Analytical Chemistry, Faculty of Chemistry, Saint-Petersburg State University

At present for carrying out of spectral analysis of liquid samples the most called-for methods are atomic emission spectral analysis with inductively-coupled plasma and atomic absorption spectral analysis with electrothermal atomization in carbon furnace. Atomic emission analysis is multielement but needs usually more than 1 ml of a sample. Several requests are laid to sample in point of its viscosity and salt content, i.e. sample preparation is necessary. Atomic absorption analysis possesses high sensitivity and allows to use small amounts of a sample but it is a one-element method.

Atomic emission spectral analysis of small amounts of liquid sample in arc discharge with technique of evaporation and excitation of spectrum of dried resi-due from the end of carbon electrode with digital spectrum registration possesses advantages described above which are necessary for determination of microele-ments in liquid samples.

The report contains information about ways of optimization of sample evapora-tion and atomization conditions, choosing of spectral device and detector param-eters, optimization of processing of spectrum information. Developed technique allows to determine concentration of elements from n⋅10-7 g/l using n⋅10 µl of sample. Repeatability of measurements is 10-15 % rel.; range of calibration curve linearity is more than three degree of concentration. The report also contains ex-amples of usage of this technique in the analysis of biological fluids, beverages and cosmetic products.

16

Switching on luminescence of a platinum(II) complex by conjugation with human serum albumin

Solomatina [email protected]

Scientific supervisor: Krupenya D.V., Department of Chemistry, Saint-Petersburg State University

In the context of developing metal based antitumor drugs and luminescent probes for biomolecules, platinum(II) complexes are widely investigated. Herein we report a cyclometallated square-planar Pt(II) complex bearing a triphenylphosphine ligand. The compound obtained demonstrates a binding affinity towards human serum albumin and such binding is accompanied by switching on and enhancement of luminescence at 525nm in phosphate buffer/DMSO solution.

NPt

Cl

PPh3

Fig. 1. The structure of obtained complex.

Fig. 2. Switching on of the luminescence in-tensity on the presence of HSA in solution of the complex.

Also the aforementioned complex attracts solid-state polymorphism. It forms crystals of two types with different lattice parameters which has various photo-physical properties. Solid state structures of both forms were established using X-ray crystallography.

The authors greatly appreciate the financial support of St. Petersburg State University research grants 12.37.132.2011, 12.39.1048.2012 and Russian Foundation for Basic Research (grant 13-04-40342). The work was carried out using scientific equipment of the Center of Shared Usage “The analytical center of nano- and biotechnologies of SPbSPU”. NMR studies were performed at the Centre for Magnetic Resonance, photophysical study was carried out in the Center for optical and laser materials research and XRD study was carried out in the X-ray Diffraction Centre (St. Petersburg State University).

17

Digital atomic emission spectrographic determination of trace contaminants in cosmetic shadows

Timofeeva Tatyana, Savinov [email protected]


At present there is a steady increase in demand for decorative cosmetics includ-ing the shadows. Quality control of these products is of particular focus in medicine, especially in dermatology, since the components of cosmetic preparations are in continuous contact with the human skin and can penetrate through the epithelial barrier of the body. Special attention is paid to the skin around the eyes, as the most sensitive part. For these reasons, cosmetic shadows may be potentially hazardous to human health, if the content of toxic components in them exceeds permissible limits. It should be noted that these limits are not established for all substances.

Some researchers found that heavy metals including cadmium leading to chronic diseases, lead causing hypertension and anemia, nickel - strong allergen trigging dermatitis are detected in shadows. It should be noted that the determination of toxic metals in cosmetic preparations requires the use of multielement method of analysis allowing to take information on the concentrations of microcomponents, the contents of which may be at the rate of about µg / g, for a short time with minimal sample preparation. That is why the technique of atomic emission digital spectrographic analysis of powder samples in an AC arc from the channel of the carbon electrode which was previously developed in our laboratory was used.

Results of optimization of this technique for the determination of elements including heavy metals in cosmetic shadows are given in this report as well as results of semi-quantitative comparison of the composition of cosmetic shadows from different countries.

18

Digital atomic emission spectrographic analysis of vine

Titova Anna, Savinov [email protected]


In 2006 consumption of vine in Russia was 1,02 billion liters, moreover as-sortment of vine-making products constantly increases, however infringing goods frequently appear at the market. Therefore assessment and control of quality are actual problem.

Along with organic compounds mineral substances are contained in vine, and their qualitative and quantitative variations depend on kind of grapes, degree of maturation, place where grown, agrotechnology, technology of treatment, i. e. they indicate authenticity of drink and describe regional belonging. However, many ele-ments are found in concentration on a level of tens µg/l, that is why identification requires the use of sensitive, multielement and fast method. Digital atomic emission spectrographic analysis with spectrum excitation of dried residue of sample from the end of carbon electrode in a.c. arc satisfies the requirements.

Aims of this work are study of possibilities and optimization of this method for determination of elements in vine, comparison of elemental composition of different kinds of vine and vine from different producers.

The report contains results of research of wine-making products sampling, possibility of sample storage. Elements which will be used for the future develop-ment of authenticity determination and regional belonging of vine technique were determined.

19

Adsorption properties of chalcogenide films to protein or DNA for the biochip application

Vasileva [email protected]

Scientific supervisor: Dr. Tveryanovich A.S., Department of Chemistry, Saint Petersburg State University

Diagnostic of pathogen in the human biological liquids by biochip technology is intensively developed methodic now. The most important part of biochip is the absorbing layer. Adsorption properties of chalcogenide films to protein or DNA were tested in this work for the application of biochips. The films were prepared by a conventional thermal deposition technique and by pulsed laser deposition technique. Two methods were used to forming in the films two-dimensional map of adsorbing places for probe testing. Both of them are based on the fact that chalcogenide and oxide glasses have different adsorbing ability to amine groups.

Previously, it was found that glasses of the As-S system have photostructural transformations under irradiation of light with energy above band gap. These transformations are characterized by changes in the chemical short-range structure and some properties. It can be used to creation of precision island structure with photoresist technology. The composition As39S61 was chosen for investigations. The prepared As39S61 glass was used to deposition of thin films onto standard glass slide by thermal deposition. The film thickness was about 500 nm. After that the deposited film was illuminated through a mask and etched.

Mixture of 75% triethylphosphate and 25% dipentylamine was used as the etching solution. Thus chalcogenide glassy island structure on the slide was cre-ated. These islands demonstrated the presence of selectivity to protein markers relatively slide material (oxide glass).

Ge-Ga-S glassy film undergoes photo-induced oxidation under exposure of photons with energy above the band gap. It results in fundamental changes in the chemical structure. This effect can be used to control selectivity of adsorption of protein or DNA materials by surface of chalcogenide film and thereby it can be used for creation of biochips. The composition 0,85 GeS2*0,15 Ga2S3 was chosen for this investigation. The adsorption ability of thin films the mentioned composition deposited by pulsed laser deposition to various protein probes was tested.

The obtained data shows the perspective for using of chalcogenide films as substrates for biochips with spatially defined selective adsorption of biological probes.

B.Geo- and Astrophysics

22

Extension of the i-CRS stacking operator for the 3D

Abakumov [email protected]

Scientific supervisors: Prof. Dr. Kashtan B.M., Department of Earths Physics, Faculty of Physics, St.-Petersburg University; Prof. Dr. Gajewski D., Department of Geosciences, Institute of Geophysics, University of Hamburg

The generation of a zero-offset section is the first step in seismic processing. Currently there are two powerful methods that take into account the curvature of the reflector and hence allow better fit the data. These are the Common Reflection Surface stack method and the Multifocusing method. Both methods have advan-tages and disadvantages: the MF method accurately approximate traveltimes of reflection events for the whole range of curvature while the CRS is less well suited to model the moveout of diffracted waves. Computationally the CRS approach is significantly more effective than the MF due to the so-called pragmatic search of parameters which allows to split the simultaneous three parameter optimization into several one-parametric searches.

Recently a new method, called implicit CRS (i-CRS) was developed and successfully applied to synthetic and field data. This method better fits diffracted waves and maintains the high computational efficiency of the conventional CRS stack. The result is an improved stacked section with a higher signal-to-noise ra-tio. Successful implementation of the method to monotypic waves was shown by Schwarz et al. (2012); to converted waves by Abakumov et al. (2012). The extension to the anisotropy case was proposed by Vanelle et al. (2012). All of the foregoing studies were carried out for 2D case. However, 3D seismic has become the standard exploration and production tool. Such effects as diffractions or inclination angles of boundaries cant be properly reconstructed using 2D seismic.

We propose two possible extensions of i-CRS stacking operator for 3D case. The main difference between two approaches is in chosen local approximation of the reflection interface. We compare the accuracy of approaches with the one of standard CRS stacking operator for a number of simple models. Finally we discuss the issue of connection of CRS attributes with parameters of our problem and consider the question of auxiliary media existence in 3D case.

References1. Abakumov I., Schwarz B., Kashtan B., Vanelle C., Gajewski D. (2012) 82nd Annual International SEG Mtg., Las Vegas, USA, Expanded Abstracts.2. Schwarz B., Vanelle C., Kashtan B., Gajewski D. (2012) 82nd Annual International SEG Mtg., Las Vegas, USA, Expanded Abstracts.3. Vanelle C., Bobsin M., Schemmert P., Kashtan B., Schwarz B., Gajewski D. [2012] 82nd Annual International SEG Mtg., Las Vegas, USA, Expanded Abstracts.

23

Time-lapse anomalies reconstruction via joint inversion of direct waves and reflection images: application to

crosswell data

Abakumov [email protected]

Scientific supervisors: Ph.D Kiyashchenko D.A., Shell Exploration & Production, Houston, USA; Prof. Dr. Kashtan B.M., Department of Earth Physics, Faculty of Physics, St.-Petersburg University

The algorithm of time-lapse velocity anomalies reconstruction using cross-well data is presented. Accurate re-construction of time-lapse ve-locity anomalies in inter-well space is important to under-stand Enhanced Oil Recovery processes. Conventional ap-proaches invert first arrival time delay into a velocity change and hence results sig-nificantly depend on the qual-ity of data picking. Moreover, the cross-hole tomography has limited lateral resolution due to specific acquisition geometry.

Abakumov et al. (2012) proposed to optimize the functional based on the lin-ear combination of weighted norm of correlation of time-lapse reflection images and direct arrivals. Such approach is stable with respect to phase changes in the data and the lateral resolution is improved by using reflections. Application of the method to synthetic and field data reveals the potential of this algorithm and helps to improve on the data interpretation consistency.

References1. Abakumov I., Kiyashchenko D., Kashtan B., 2012, A correlation-based cross-well time-lapse velocity analysis: Presented at the 74th EAGE Conference & Exhibition. 2. Kiyashchenko D., Mehta K.,. Lopez J., Maamari A., Adawi R., Rocco G., 2011, Time-lapse down-hole seismic surveys for deep eor target monitoring in south oman: 81st SEG Annual Meeting, pp. 4244–4248.

Fig. 1. Reconstructed velocity anomalies for time-lapse tomography cost functions (a), reflection to-mography (b), joint inversion and previous result (d), [2]. The temperature log is shown at the loca-tion corresponding to observation well.

24

Multi-wavelength evolution of the solar complex activity

Korolkova [email protected]

Scientific supervisjr: Dr. Benevolenskaya E.E., Department of Earth’s Physics, Faculty of Physics, Saint-Petersburg State University

The main problem of the solar physics is to understand a nature of the solar magnetic activity. New space missions and background observations provide us by data describing solar activity with good space and time resolution. Space mis-sions data observe the solar activity in multi-wavelength emissions come from photosphere to corona. The complex of the solar activity has roots in interior and extends to the solar corona. Thus, modern data give an opportunity to study the activity on the Sun at different levels simultaneously.

Solar Dynamics Observatory (SDO) [1] which launched at the beginning of 2010, looks at Sun in different wavelengths such as coronal lines 171Å, 193Å, 211Å & 335Å. Also SDO measures photospheric magnetic flux (line-of-sight component of the magnetic field strength).

I have studied a stable complex of the solar activity (NOAA 11689) during 6 hours started on 10 March 2013 using 720s cadence of HMI (Helioseismic and Magnetic Imager) [2] and AIA (Atmospheric Imaging Assembly) [3] instruments of SDO.

Here I present the first result of evolution the region NOAA 11689 and a rela-tionship of the magnetic flux and coronal emissions.

References1. Pesnell W.D., Thompson B.J., Chamberlin P.C. // Solar Phys., v. 275, p. 3-15, (2012).2. Scherrer P.H., Schou J., Bush R.I. et al. // Solar Phys., v. 275, p. 207-227, (2012).3. Lemen J.R., Title A.M., Akin D.J. et al. // Solar Phys., v. 275, p. 17-40, (2012).

25

Evolution of isolated OB associations in the Milky Way

Korsunov [email protected]

Scientific supervisor: Prof. Dr. Kholtygin A.F., Astronomy Department, Mathematics and Mechanics Faculty, Saint-Petersburg State University

OB associations are young and sparse star clusters, containing majority of young massive stars of O and B spectral classes in the Milky Way. The kinematics of OB associations determines the spatial distribution and kinematics of OB stars and their progenies, neutron stars and stellar-mass black holes. Unfortunately, for the lack of observational data related to the low-mass component of OB as-sociations and distribution of associations on the galaxy scale, that kinematics is mainly unknown.

The current work is focused on the internal kinematics of isolated OB associa-tions. The evolution of association during lifetime of massive stars are modelled taking into account stellar evolution and escapers detection. Different aspects of models physics are constructed using existing codes for astrophysics simula-tions, e. g. phiGRAPE (N-body calculations) and SSE/BSE (stellar evolution). Code coupling are handled by AMUSE (Astrophysical Multipurpose Software Environment) framework.

Various kinematics characteristics of the associations, such as the temporal evo-lution of total energy, velocity dispersion, mean radius, core radius and kinematic temperatures of different components are obtained. These characteristics can be compared with the observational data for nearest associations such as Sco OB2. Thorough statistics and external kinematics are subjects of future work.

26

Spiral structure and bulge/disc decomposition analisis

Savchenko Sergey, Mosenkov [email protected], [email protected]

Scientific supervisor: Dr. Reshetnikov V.P., Department of Astrophysics, Faculty of Mathematics and Mechanics, Saint-Petersburg State University

We present a new Python wrapper, DECA (DEComposition Analysis), devoted to investigate images of regular galaxies in an automated mode. This code is based on using some popular astrophysical software (IRAF, SExtractor, GALFIT) as well as some standard and specific Python modules.

DECA is able to do quantitative morphological classification of galaxies. One of the most important DECA applications is structural analysis of edge-on galax-ies including bulge/disc decomposition and estimation of disc warps, truncations, bulge ellipse shape and the law of surface brightness distribution along the radius. However, DECA is created to investigate not only edge-on galaxies. The great advantage of it is a new developed technique to analyze spiral structure of not highly inclined galaxies and derive bulge and disc structural parameters as well as parameters of the spiral structure (e.g. pitch angle, arm width) if spiral pattern can be well detected in the image. This module finds the initial parameters of the spiral structure using the Fourier transform. The initial parameters of spirals undergo the process of fitting along with other structural parameters of galaxies. DECA is now generally available to the astronomical community.

We have tested our code on the sample of simulated galaxies (built images com-posed by three components: bulge, disc and spiral pattern with known in advance values of parameters). One of our main goals is to determine whether taking into account the spiral pattern can give better estimations of main parameters than using simple bulge+disc model. We show that such more complex model with spiral pat-tern does provide better results of retrieving bulge/disc parameters as well as spiral parameters. The method applied here to decompose galaxies with spiral structure in mass regime has not been proposed before and seems to be very applicable to solving a problem of estimating the spiral parameters.

We have applied our code to decompose real spiral barless galaxies selected from the Galaxy Zoo Catalogue of Spiral Galaxies. Only sufficiently large galax-ies (d(B)>55'') were analyzed. The images in g-band were taken from the Sloan Digital Sky Survey dr9. The results show that there exist tight correlations between bulge and disc structural parameters. The most significant result of this work is a more precise definition of correlations between some structural parameters of disk galaxies, e.g. between the shape of spirals and the parameters of central bulge. This new information is of great importance to study physical processes in spiral galaxies and can become one of the clues to develop existing galaxy formation and evolution theories.

С. Mathematics and Mechanics

28

On the solvability of ordinary differential equations with integral conditions

Darovskaya [email protected]

Scientific supervisor: Prof. Dr. Skubachevskii A.L., Department of Differential Equations and Mathematical Physics, Faculty of Science, Peoples’ Friendship University of Russia

We consider an ordinary differential equation of the order 2m together with integral conditions. These nonlocal conditions contain the linear combination of derivatives of the unknown function under the Riemann integral. The order of derivatives is between 0 and 2m-1 [3], weight functions are considered nonsmooth [2, 4]. Our first aim is to obtain an a priori estimate of the solution and then study the solvability and spectral properties of the problem.

Our main method to achieve this goal is to separate nonlocal terms and, there-after, to use properties of the “local” problem (based on the technique of elliptic problems with parameter, see [1]) and ones of the auxiliary problem. In the study of the last one, two main difficulties arise: the construction of model nonlocal conditions and the choice of appropriate function spaces with proper (equivalent) norms.

In the present work we will discuss possible ways to get over the mentioned difficulties.

This work was supported by the RFBR, project No. 13-01-00422.

References1. Agranovich M.S., Vishik M.I. // Usp. Mat. Nauk, 19, No. 3, 53-161, (1964).2. Darovskaya K.A., Skubachevskii A.L. // J. Math. Sci., Vol. 179, 3, 437-445, (2011).3. Shkalikov A.A. // Moscow Univ. Math. Bull., Vol. 37, 6, 10-20, (1982).4. Skubachevskii A.L. // J. Math. Sci., Vol. 155, 2, 199-334, (2008).

29

Stability of CW Solutions of Fourier Domain Mode Locked Laser

Kashchenko [email protected]

Scientific supervisor: Prof. Glyzin S.D., Department of Mathematical Modeling, Faculty of Mathematics, Yaroslavl State University

Consider Fourier Domain Mode Locked Lasera+a=κ1/2e(1-iα)g(t-T)/2a(t-T)e-iωT,

g=γ(g0-g-g|a|2)with large delay (T>>1). Here α and ω are real, γ and g0 are positive, 0<κ<1, κexp(g0)>1.

This equation has family of CW solutions a=ρeiδt, g=const. Stability of these solutions in dependence of parameters κ, α, ω, γ, g0 in case of large delay T is studied. Sufficient conditions of stability and instability are found. Multistability and even hypermultistability is proved. (Hypermultistability means that for any natural number n we can find parameters of our problem, such that we have greater or equal than n stable coexisting solutions).

30

Design and Control Strategies of Anti-Lock Braking Systems

Koeppen [email protected]

Scientific supervisor: Prof. Dr. Kuepper T., Mathematical Institute of the University of Cologne

In the field of dynamical systems periodic orbits are of great interest. They correspond to a certain behavior of the system that can be desired or unwanted. Thus, finding and analysing periodic orbits is one certain area of interest. In most cases, dynamical systems are non-integrable and can only be solved by numerical simulation. This can be sufficient, but sometimes an analytical approach can be beneficial. In this presentation, an alternative based on perturbation theory is shortly introduced that allows finding closed orbits not numerically, but analytically.

The main focus of the presentation is on a model of an anti-lock braking system (ABS). ABS are by now a standard component in every modern car. They prevent the wheels from going into a lock situation where the wheels are fixed by the brake and the stopping distances are greatly prolonged. In literature, there are different approaches to such control logics. An ABS design based on [1] is presented that consists in controlling the wheel’s slip by creating certain, stable limit cycles in the corresponding phase space. It is then modified and analysed by the presented analytical approach.

References1. Tanelli M., Osorio G., Di Bernardo M.S., Savaresi M., Astolfi A. // International Journal of Control Vol. 82, No. 4, April 2009, 659-678.

31

Limit Cycles in Economics

Li [email protected]

Scientific supervisor: Dr. Giannakopoulus F., Mathematical Institute, Faculty of Mathematics and Natural Sciences, University of Cologne

Nowadays, dynamical systems are applied for analysis of problems in many fields. In economics, dynamical models are also often used to present the property of the market.

The aim of this talk is to present the general theories of the existence of limit cycles for autonomous systems, which was used mostly in the economic time of Keynesian after the second world war. The most significant theory of the existence of limit cycle will then be the Poincare Bendixson theorem.

Further I will use the theories in a simple economic model- the Kaldor’s model-, and show at first the basic idea of this model, which is entirely Keynesian in spirit, that investment and the saving functions are both functions of output and the capital stock.

Finally I will prove both graphically and mathematically the existence of busi-ness cycle using the Poincare Bendixson theorem by the Kaldor’s model. We will see, the business cycle corresponds the stable equilibrium between supply and demand in the market.

References1. Economic Dynamics, Giancarlo Gandolfo, 4.Edition, Springer-Verlag, P 434-448.2. Gewöhnliche Differenzialgleichungen, Bernd Aulbach, 2. Auflage, P 175-180 und P 403.

32

Scattering of Solitons for Coupled Wave-Particle Equations

Mashkin [email protected]

Scientific supervisor: Prof. Dr. Kunze M., Mathematical Institute of the University of Cologne

We consider a nonlinear system of wave equation coupled to a charged par-ticle. The coupled system admits soliton solutions which de_ne a six dimensional solitary mani-fold.

The aim of the talk is to present a long time soliton asymptotics for the system and to sketch the strategy of the proof.

Any solution with initial state close to the solitary manifold, converges in long time limit to the sum of a soliton and a dispersive wave which is a solution to the free wave equation (according to [1]).

The approach is based on the symplectic projection in Hilbert space onto the solitary manifold, modulation equations for the parameters of the projection, and decay of the transversal component.

References1. Imaykin V., Komech A.I., Vainberg B. // J. Math. Analysis and Appl. 389 (2012), 713-140.

33

Analysis of the oscillatory regimes of the second-order nonlinear delay differential equation

Moryakova [email protected]

Scientific supervisor: Prof. Kubyshkin E.P., Department of Mathematical Modeling, Faculty of Mathematics, Yaroslavl State University

The research is devoted to the investigation of the second-order nonlinear delay differential equation

( ) 0x Ax x kf x+ + + = .Here

2 32 3( ) ( ) ( ) ( )f x x t g x t g x tθ θ θ= − + − + −

is a smooth function, A, K >0 are parameters, θ is the delay of the argument. This equation arises in the mathematical simulation of electronic devices. It is shown that equation can have complex (including chaotic) oscillations. For investigation method of integral manifolds has been implemented, which allowed to consider finite system of ordinary differential equations describing the behavior of the solu-tions on the stable invariant manifold in the vicinity of the zero solution instead of original equation. This system of equations is called the normal form of the original differential equation corresponding to the considered critical value.

Characteristic equation of the linear part of the equation has two pairs of complex conjugate roots with resonance 1:3. The other roots of the characteristic equation lie in the left open complex half- plane. In the vicinity of the zero solu-tion the original equation has a four-dimensional asymptotically stable smooth invariant manifold, the behavior of solutions on which defines the solutions of the original equation. To study the behavior of the trajectories on the invariant manifold normal form was constructed and it analytical and numerical analysis has been carried out.

Depending on the incoming parameter the normal form can have two stable periodic solutions or dual frequency stable torus, and can have a stable chaotic os-cillatory regime occurring through a series of period doubling bifurcations. For the chaotic regime Lyapunov exponents and Lyapunov dimension has been counted.

34

Regularity of solutions to functional differential equations

Neverova [email protected]

Scientific supervisor: Prof. Skubachevskii A.L., Department of Differential Equations and Mathematical Physics, Peoples’ Friendship University of Russia

This investigation is devoted to the theory of boundary value problems for special case of functional differential equations that is differential-difference equa-tions which have many applications. Boundary value problems for such equations arise in the study of elastic deformations of multilayered plates and shells [1], the damping problem for a control system with aftereffect [2], etc. On the other hand, boundary-value problems for differential-difference equations can be reduced to differential equations with nonlocal boundary conditions. This approach was used in application to the plasma theory [3].

It should be noted that the solutions of boundary-value problems for differ-ential-difference equations have some fundamentally new properties. In addi-tion, smoothness of generalized solutions to the boundary-value problem for a differential-difference equation with the shifted argument in the higher derivative can be violated even for infinitely differentiable right-hand side of the equation (for example, see [3]).

We study the solvability Dirichlet, Neumann, and Robin boundary value problems for differential-difference equations with continuous right-hand side on a finite interval (0, d) and the smoothness of solutions to such problems. We have obtained necessary and sufficient conditions of the coincidence of generalized and classical solutions to Dirichlet, Neumann, and Robin boundary value problem. For the first boundary value problem earlier we obtained [4] coinciding necessary and sufficient conditions for the existence of a classical solution to such problems for differential-difference equations with an arbitrary continuous right-hand under the assumption of variable coefficients of difference operators. For Neumann and Robin problems necessary and sufficient conditions do not match.

The results were obtained with the support of G-RISC Project № M-2013a-3, RFBR grant № 13-01-00422.

References1. Onanov G., Skubachevskii A. // Soviet Applied Mech. 15 (1979).2. Krasovskii N. Control Theory of Motion. -Moscow: Nauka, 1968 (Russian).3. Skubachevskii A. Elliptic functional differential equations and applica-tions (1997).4. Neverova D., Skubachevskii A. // Differential Equations, 2013, Vol. 49, No. 3, pp. 288–297.

35

The research of attractors of quasi-linear Korteweg-de Vries equation

Preobrazhenskaia [email protected]

Scientific supervisor: Dr. Kolesov A.Y., Department of Differential Equation, Faculty of Mathematic, Yaroslavl State University

The method of quasi-normal forms was used for research of singularly per-turbed model RCLG-generator, which under certain additions has been reduced to a boundary value problem of the form ut+u xxx= εχu xx+εu− u3 , (1) u ( t , x +1)= − u( t , x) , (2)where 0<ε<<1, χ = const >0. The phase space of this system is the Sobolev space W 2

3 antiperiodic with period 1.The essence of the method of quasi-normal forms is as follows. Process

of formal infinite-dimensional normalization is applied to the system, which results in a countable system of ordinary differential equations — the so-called quasi-normal form. Next, the known results (see [2]) about the correspondence between the invariant tori quasi-normal forms and invariant tori of the original problem is applied.

In the present work, this method of quasi-normal forms used to investigate question of the existence and stability of invariant tori of different dimensions the boundary value problem (1), (2) the method of quasi-normal forms. As a quasi-normal form of this problem is obtained countable system of ordinary differential equations of simple structure, for which the equilibrium is found explicitly.

It is stated that only cycles like traveling wave u(x,t)= û(y) π where y=(2k+1)3π3t + (2k+1)πx, k = 0,1,2,…, û(y+1)=- û(y) of the original system are stable. Tori with dimension greater than two are unstable. With decreasing values of the parameter χ number of simultaneously existing stable cycles unlimited increases, and if χ=0, the number is countable. This shows that within the boundary value problem (1), (2) is implemented, the buffer phenomenon, which consists in the presence of the system at an arbitrarily large number of similar attractors. Note that in this case attractors is not just a lot, but there is a mechanism of accumulation.With the help of numerical experiments managed to find out that the problem (1), (2) has the buffer phenomenon including when ε<<1.

References1. Kolesov A.Y., Mishchenko E.F., Rozov N.H. // New methods for proving the existence and stability of periodic solutions of singularly perturbed systems with delay, Proceedings of the Steklov Institute of Mathematics, v. 259, p. 106-133 (2007).2. Kolesov A.Y., Rozov N.H. // Invariant tori of nonlinear wave equations. - Moscow: FIZMATLIT, 408 p. -ISBN 5-9221-0515-9, ( 2004).

36

Geometric Sparsity and Structured Compressed Sensing

Stojanoska [email protected]

Scientific supervisor: Prof. Dr. Gitta Kutyniok, Department of Mathematics, Faculty of Mathematics and Natural Sciences, Technische Universität Berlin

Compressed sensing is a novel methodology in data processing which in the past decade became intensively investigated and widely used by applied mathemati-cians, engineers, statisticians, theoretical computer scientists and others. Biology, medicine, communication, imaging science are just a few of the examples where compressed sensing has found an application.

This methodology takes an advantage of the fact that most signals admit a sparse representation. In such a case it then allows to recover the signal from considerably less measurements than those required by traditional methods.

We are interested in exploiting additional information about the signal, namely having a sparse geometric structure. One goal in this setting is to improve the com-pressed sensing results over those where no structure is assumed. Another goal is to broaden the range of applications of the compressed sensing methodology.

We will present results about signals consisting of unions of discrete lines as the simplest case of geometric sparsity. We will discuss their properties and the application of compressed sensing to such signal models. As an applica-tion we solve the problem of separation of discrete lines and points in a two dimensional signal.

References1. Davenport M.A., Duarte M.F., Eldar Y.C., Kutyniok G. Introduction to Compressed Sensing. Compressed Sensing: Theory and Applications, Edited by Y.C. Eldar and G. Kutyniok, Cambridge University Press, Chapter 1, (2012).2. Kutyniok G. Data separation by sparse representations. Compressed Sensing: Theory and Applications, Edited by Y.C. Eldar and G. Kutyniok, Cambridge University Press, Chapter 11, (2012).3. Reveillès J.P. Géométrie discrète, calcul en nombres entiers et algorithmique, Ph.D. Thesis, Université Louis Pasteur, Strasbourg, France, (1991).

37

On strongly elliptic functional-differential equation with orthotropic contractions

Tasevich [email protected]

Scientific supervisor: Prof. Rossovskii L.E., Department of Differential Equations and Mathematical Physics, Faculty of Science, Peoples’ Friendship University of Russia

Let Br – a two-dimensional ball of radius r centered at the origin. In Br we consider the following partial differential equation whose leading terms contain transformations of arguments of the unknown function in the form of contractions and dilatations:

1 21 1 2 2

1 21 2 0 1 2 1 2 , 1 1

( ) ( ),

( , ) ( , ) , , .

R

i i i i

u uA u x R R f xx x x x

x xR u x x a u x x a u px a u qxq p−

∂ ∂ ∂ ∂= − + = ∂ ∂ ∂ ∂

= + +

(1)

Definition 1: The equation (1) is called strongly elliptic in the closure of Br, if there exist the constants c1>0 and c2≥0 such that for all u from C0

∞ (Br) the Gårding type inequality holds:

( ) ( ) ( ) ( )2

22

2 21 2Re , .

r rrR H B L BL B

A u u c u c u≥ − (2)

Theorem 1: Equation (1) is strongly elliptic if and only if

2 1

2

1 1Re 0j

i iji j

aξ λ= =−

>∑ ∑

( , 1).q pλ ξ= = (3)

Some results on the solvability and smoothness of the generalized solutions of strongly elliptic equation (1) are given. The case of orthotropic contractions combines the methods applied for difference-differential equations [1] and functional-differential equations with isotropic contractions [2-4] but it is not similar to neither of them.

References1. Skubachevskii A.L. // Diff. Eq., v. 63, № 3, P. 332-361, (1986).2. Rossovskii L.E.// Math. Notes, v. 59, P. 75-82, (1996).3. Rossovskii L.E. // Dokl. Math., v. 82, № 2, P. 765-768, (2010).4. Rossovskii L.E.// Contemp. Math. Fundam. Directions, v. 45, P. 122-131, (2012).

D. Solid State Physics

40

Investigation of electronic properties of the Si – low-melting salt interfaces

Bekasov [email protected]

Scientific supervisor: Prof. Dr. Yafasov A.M., Department of Solid State Electronic, Faculty of Physics, Saint-Petersburg State University

The aim of the present work is to investigate the semiconductor – low-melting salt interfaces by field-effect in electrolyte methods. This method allows us to determine the parameters of the semiconductor directly during the action at the interface (in situ). The electrolyte was performed by eutectic (low-melting salt) KF-HF-H2O, the main feature of it is presence of fluorine ion without solvent net envelope.

Investigations of the semiconductor – low-melting salt interfaces are motivated by theoretical and applied needs. Knowledge about behavior of fluorine ion without solvent net envelope on silicium surface is needed for understanding structure of silicium surface. Other fluorine-containing materials like hydrofluoric acid are used in silicium investigation and engineering process, but most of them have a number of disadvantages like toxicity and volatility, low-melting salt like KF-HF-H2O pretends to replace them because of its usability.

Investigation of silicon in contact with the fluorine-containing substances has been practiced for a long time. Thus, the system Si-24% HF [1] allowed to bypass the difficulties associated with the presence of the oxide layer on the silicon surface and to conduct a comprehensive investigation of the electrophysical processes of the interface.

References1. Sultanmagomedov S.N. // Electrophysical properties Si in contact with the electrolyte. PhD dissertation, Leningrad University, Leningrad (1980).

41

Growth of graphene with boron impurities and its electronic structure

Bokai [email protected]

Scientific supervisor: Dr. Usachov D.Yu., Department of Solid State Electronics, Faculty of Physics, Saint-Petersburg State University

Graphene is currently considered as a perspective material for future electronics. However, its zero band gap and low charge carrier concentration prevent it from wide implementation in electronic devices. That is why the doping of graphene to manage its polarity of conductivity and carrier concentration is necessary. Doping of graphene with boron atoms may open a band gap and make it a p-type semiconductor instead of a semi-metal. Unlike other works devoted to graphene doping [1-2] we present a different way for synthesis of graphene sheet with boron impurities.

In present work we report on the synthesis of boron-doped graphene layers on Ni(111) in a chemical vapor deposition process from carborane and propylene. In order to achieve information about the possible surface structure we prepared boron-doped graphene layers with different dopant concentrations up to 18 at.%. The chemical environment of boron was determined by X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. To analyze the impact of boron doping on band structure we used the angle-resolved photoelectron spectroscopy. Boron doping leads to a shift of graphene bands to lower binding energies. This shift depends on boron doping concentration and reaches value of 0.5 eV in case of 18 at.% of boron, which may indicate notable charge transfer. Using X-ray absorption spectroscopy we have found that boron impurities are located in graphene plane. Electron diffraction together with photoemission shows that impurities randomly substitute carbon atoms in graphene lattice and our preparation technique does not lead to formation of ordered structures.

In future we will try STM investigation and density-functional theory calcula-tions that should help us to determine the exact structure of defects and value of the charge transfer.

This work was supported by the President's grant MK-3303.2012.2, RFBR grant 11-03-00752 and SPbSU grant 11.37.634.2013. Part of the research was carried out in resource center of SPbSU "Physical Methods of Surface Investigation".

References1. Gebhardt J., Koch R.J., Zhao W., Höfert O., Gotterbarm K., Mammadov S., Papp C., Görling A., Steinrück H.-P., Seyller Th. // Phys. Rev. B 87, 155437 (2013).2. Quandt A., Ozdogan C., Kunstmann J., Fehske H. // Phys. Stat. Sol. B 245, 2077-2081 (2008).

42

Plasmon-LO-phonon Modes in Gallium Nitride Epitaxial Layers Doped with Silicon

Borisov [email protected]

Scientific supervisor: Prof. Dr. Agekian V.F., Department of Solid State Physics, Faculty of Physics, Saint-Petersburg State University

Gallium nitride (GaN) and various related nanostructures are among the semi-conductor systems in demand for the most important applications and scientific purposes. Due to the wide energy gap GaN is used to fabricate the UV lasers, light emitting diodes and other devices which operate at high temperatures. The GaN crystals exist in two crystalline phases: a cubic and a hexagonal.

The aim of this work is to study the Raman spectra of the hexagonal GaN lay-ers doped with silicon within the wide range from 4.1∙1016 cm-3 to 4.8∙1019 cm-3 at room temperature. These gallium nitride layers were grown by the vapor phase epitaxy on the sapphire substrate with the undoped GaN buffer layers.

The silicon donor states are separated from the conduction band by 30 meV that is the majority of donors are ionized at room temperature. The lattice vibration is affected by the high concentration of free carriers resulted in the plasmon-LO-phonon (LOPC) modes formation. The energy positions of the plasmon-LO-phonon bands are used to determine the free carrier concentration in the series of GaN samples. The donor concentrations obtained for the series of GaN:Si layers within the wide range of silicon concentrations are in the excellent agreement with the Hall measurements.

The vibrational modes A1, E1, E2(1) and E2(2) of undoped buffer GaN is also observed in the Raman spectrum as well as the sapphire substrate modes. This suggests the low electron concentration in the buffer layer even at room tempera-ture. The TO-modes is not observed in the backscattering geometry used in our experiments.

Acknowledgements. All the spectra were obtained at the Center for Optical and Laser Materials Research of Saint-Petersburg State University.

43

Synthesis of ultrathin magnetic films of transition metals silicides (Fe, Co, Mn) on silicon surface

Grebenyuk [email protected]

Scientific supervisor: Dr. Pronin I.I., Laboratory of Physics of Elementary Structures of Surface, Division of Plasma Physics, Atomic Physics and Astrophysics, Ioffe Physical Technical Institute

Thin magnetic films of transition metal silicides are very perspective for mi-croelectronics and spintronics, because on the one hand they are easy to integrate into the standard silicon technology and on the other they can be used as sources for injection of spin-polarized electrons into a semiconductor. In this work we have used identical experimental conditions to study the formation of ultrathin silicide films at Fe/Si, Co/Si and Mn/Si interfaces. Specific features of the evolution of each system are revealed, and correlations are established between their phase composition and magnetic behavior.

The silicides were grown on the atomically clean silicon surfaces in ultra-high vacuum by solid-phase epitaxy. Their characterization was performed in situ by high resolution photoelectron spectroscopy and magnetic linear dichroism in metal 3p core-level photoemission.

At room temperature the initial stages of the interface formation are similar for the investigated systems. The process starts with the growth of interfacial monosili-cide film followed by island formation of metal-silicon solid solution or metal-rich silicide. The in-plane ferromagnetic ordering of the Co/Si and Fe/Si interfaces has a threshold nature and arises after the deposition of ∼ 6 Å of metal when the solid solution film becomes continuous and the pure metal film begins to grow. The Mn/Si interface has not demonstrated the effect of magnetic linear dichroism.

Solid-phase reactions in Co/Si system start at ∼250°С when the formation of the ferromagnetic Co3Si silicide is observed. The temperature rise to 360°С leads to the disappearance of Co3Si and the growth of nonmagnetic CoSi layer. The reac-tions in the Fe/Si system start at lower temperature (about 100°C). We observed the transformation of the Fe film into the Fe3Si silicide. Annealing at 200°C results in a conversion of Fe3Si to the nonmagnetic ε-FeSi silicide. Thermostimulated processes in Mn/Si system start at temperature of 150°C and do not lead to the formation of ferromagnetic phases with a Curie temperature above room temperature. Further annealing results in the formation of MnSi and MnSi1.7 islands on the sample surface at 200°C and 600°C respectively.

The study was supported by Russian Foundation for Basic Research (Project no. 13-02-00398) and the Russian-German Laboratory at HZB-BESSY.

44

X-ray reflectometry study of Al2O3-based heterostructures

Konyushenko [email protected]

Scientific supervisor: Prof. Dr. Filatova E.O., Department of Solid State Electronics, Faculty of Physics, Saint-Petersburg State University

Aluminum oxide (Al2O3) is considered as a suitable insulator for various elec-tronic application ranging from gate dielectric in Complementary Metal-Oxide-Semiconductor transistors to trapping or blocking insulator in charge non-volatile memory cells. This fact is explained by a high dielectric constant (k≈10), a large band gap (5-9 eV) and thermodynamic stability on Si. It is known that Al2O3 is crys-tallized in several modifications, where the Al atom can occupy both tetrahedrally and octahedrally coordinated sites in different proportion. Before the amorphous Al2O3 actively used in the flash memory cells, but at the present time the ability to use γ-Al2O3, which is perfectly suited for non-volatile memory application [2] is discussed. The goal of this work is to study the influence of annealing conditions on the γ-Al2O3 crystallization.

All the measurements were carried out using x-ray reflection spectroscopy on the optics beamline BESSY-II of the HZB. The absorption spectra were calculated from measured reflection spectra using the Kramers-Kronig relations. Analysis of the AlL2,3-absorption spectra of α-Al2O3, γ-Al2O3 and amorphous Al2O3 allows to identify the spectral features connected with modifi cation of the crystalline struc-modification of the crystalline struc-ture of the film. The value of the energy distance between these features carries the information about a modification of the crystalline structure. The value of the ratio of their intensities is related with proportion of tetrahedrally and octahedrally coordinated sites of Al atom. Using this information the Al2O3 nanofilms, grown on TiN- or TaN-electrode and subjected to rapid thermal annealing at various condi-tions were studied. Joint analysis of the AlL2,3- and OK-absorption spectra points to: i) the thermal annealing changes the structure of Al2O3 film from amorphous to the γ-Al2O3 phase; ii) step-by-step annealing the system increases the contribu-tion of octahedron coordination AlO6 in the structure and insignificantly decreases number of defect states; iii) the number of defect states depends strongly on the electrode material and maximal in the case of film grown on the TaN-electrode as compared with TiN-electrode film; iiii) the structure of the film depends on the electrode material and corresponds to cubic/polycrystalline γ-Al2O3 phase depend-ing on TiN/TaN-electrode material.

References1. Toyoda S. et al. // J. Appl. Phys, № 101, p. 231607, (2012). 2. Afanas’ev V. et al. // J. Appl. Phys, № 99, p. 072103, (2011).

45

Rashba effect in Graphene grown on different substrates

Marchenko [email protected]

Scientific supervisors: Prof. Dr. Shikin A.M., Faculty of Physics, Saint-Petersburg State University; Prof. Dr. Rader O., Helmholtz-Zentrum Berlin für Materialien und Energie

Graphene, a two-dimensional layer of carbon atoms, shows fascinating elec-tronic properties because of its structure consisting of two equivalent sublattices that determine its band structure with linear dispersion of the graphene π-band near K points in reciprocal space. Due to small atomic number of carbon atoms the intrinsic spin–orbit coupling in graphene is very weak, of the order of only 0.05 meV, which, together with the high carrier mobilities, suggests a long spin-coherence length. This low intrinsic spin-orbit coupling in graphene can be strongly enhanced by an extrinsic effect of interaction of graphene with underlying substrate. The work is devoted to study of the presence and magnitude of the Rashba effect in electronic structure of graphene induced by different substrates.

We have found a giant Rashba-type spin-orbit splitting of ~100 meV by spin- and angle-resolved photoelectron spectroscopy when graphene layer is located on top of gold layer. The splitting is constant with binding energy and extends up to the Fermi energy in slightly p-doped graphene. We compare this result to graphene on iridium, on which several different graphene moiré phases were prepared. In case of R0 phase there is a giant Rashba splitting of ~50 meV, in case of Rε phases splitting is reduced around 2 times compared to the R0 case.

In contrast, when graphene layer is located on top of on low atomic number metals (silver, copper) or on semiconductor (silicon carbide), we see no spin-orbit splitting detectable by spin-resolved photoelectron spectroscopy. In case of graphene on ferromagnets (nickel, cobalt) we see a high spin polarization of the graphene Dirac-cone, which nature is related to exchange splitting in cobalt. No Rashba-type spin-orbit splitting was detected also, as for other low atomic number metals.

46

Optical and electric properties of GaN crystals grown by HVPE

Medvedev [email protected]

Scientific supervisor: Prof. Dr. Vyvenko O.F., Department of Solid State Electronics, Faculty of Physics, Saint-Petersburg State University

Gallium nitride is a promising direct-gap semiconductor with a band gap of 3.4 eV. A favorable combination of physical and chemical properties of the GaN opens up broad prospects for application in various fields of electronics. The high thermal, chemical and radiation resistance of gallium nitride makes it suitable for the manufacture of devices operating at high temperatures and in harsh environments. Widespread GaN was introduced in optoelectronic industry the first already in 1990. But despite of many attempts during past few years the technique to achieve a good quality of the crystals was not still developed due to the lack of GaN substrates and the necessity to use other substrates with a large lattice mismatch.

The crystals were grown on sapphire by hydride vapor phase epitaxy (HVPE) method and contained as-grown dislocations of a density as high as 1010/cm2. They were investigated with secondary electron microscopy (SEM), cathodolu-minescence (CL) as well as with optical microscopy. A variety of morphological features of the samples grown at diverse was found and identified [1]. CL study revealed spatial inhomogeneity of the crystals. Spectral analysis of the peaks were performed for different regions of the crystal including regions of so-called “pits”. Recombination properties of dislocations introduced by sample scratching were also investigated.

CL and morphological properties were found to vary greatly dependent on the growth conditions: temperature, pressure, gas flow. CL spectra taken from bulk part of the crystal were compared with spectra obtained from that taken within pits and noticeable spectral CL-line positions were registered. From the shift of spectral lines elastic strains at their boundary regions were derived.

Au/GaN Schottky diodes were successfully fabricated and the net-donor density 4∙1016 cm-3 were obtained from capacitance voltage characteristics.

References1. Voronenkov V., Bochkareva N., Gorbunov R., Latyshev P., Lelikov Y., Rebane Y., Tsyuk A., Zubrilov A., Shreter Y.// J. Appl. Phys. 52 (2013) 08JE14.

47

DFT modeling of the MoS2 nanoparticles

Mikheenko [email protected]

Scientific supervisor: Dr. Shelyapina M.G., Department of Quantum Magnetic Phenomena, Faculty of Physics, Saint-Petersburg State University

MoS2 exhibits similar properties as noble metals and excellent catalytic behavior in several reactions, especially for hydrodesulfurization (HDS) and hydrogenation (HYD). Earlier research suggested that HDS reactions of sulfur-containing com-pounds occur at characteristic brim sites at the edges of MoS2 nanoclusters and that HDS can take place following two different pathways: the HYD pathway, in which several hydrogenation steps precede sulfur extrusion, and the direct des-ulfurization pathway [1]. From this perspective deeper knowledge on the MoS2 cluster geometry and their electronic structure are required.

The aim of the present work is the theoretical study of properties of (MoS2)n (with n = 1, …, 5) clusters, such as the optimized geometry, electronic density distribution, energy of formation and gap between the highest occupied and the lowest unoccupied molecular orbitals (the HOMO-LUMO gap).

The calculations have been carried out within the framework of the density functional theory (DFT) method applying the B3LYP hybrid exchange-correlation functional and 3-21G basis set using the GAMESS program package. Self-consistency of calculations is considered achieved when the total energies have converged by 0.1mRy. The results of cluster calculations have been compared with the bulk one calculated using the Full-Potential Linearized Augmented Plane Wave method using the Wien2k program package.

It has been found that the smallest cluster containing one formula MoS2 unit exhibits a rather large HOMO-LUMO gap of about 2 eV. However, it decreases with the cluster size increasing, and for n = 5 it achieves the value of 1.0 eV that is in fair agreement with the bulk data (0.9 eV).

The work has been performed using the equipment of "Saint Petersburg State University Computer Center".

References1. Topsøe H., Clausen B.S., Massoth F.E. Hydrotreating Catalysis, Springer Verlag, Berlin, 1996.

48

X-ray transitions in single Mg, Mg++ and in MgO crystal

Milov [email protected]

Scientific supervisor: Prof. Dr. Abarenkov I.V., Department of Quantum Mechanics, Faculty of Physics, Saint-Petersburg State University

In the present work the X-ray dipole transitions probabilities in single Mg, Mg++ and in MgO crystal were performed. The wave functions of initial and final states were calculated within the Hartree-Fock approximation using the pseudopotential theory.

The embedding potential method was employed for the MgO crystal electronic structure calculations. In this method, a finite part of the crystal, referred to as cluster, is considered instead of an infinite crystal and the influence of rest of the crystal onto the cluster is simulated by the embedding potential. The particular embedding potential used in this work consists of two parts, far environment and near environment. The far environment part takes account of all atoms of crystal situated outside the cluster, and the near environment part describes the influence of the terminating atoms of the cluster. The far environment part construction pro-cedure is based on the new unit cell concept, the unit cell with additional charges, which is described in detail in [1]. The near environment part is developed in Coulomb approximation. It means that point charges are put at the points where terminating atoms of the cluster nuclei are situated and these charges values are equal to the product of charge per one bond and the number of bonds which are directed outward of the cluster for each of the terminating atom.

Calculations of transition probabilities were made in two different forms, namely length form and velocity form.

References1. Abarenkov I.V. // Phys.Rev.B Vol.76, No.16 (2007).

49

Structure and morphology of selenium containing nanosystems

Nikolaev [email protected]

Scientific supervisors: Prof. Dr. Adamchuk V.K., Department of Solid State Electronics, Faculty of Physics, Saint-Petersburg State University; Dr. Sukhanova T.E., Institute of macromolecular compounds, Russian Academy of Sciences

Synthesis and investigation of selenium containing hybrid polymer nanosys-tems is an actual problem today. Such systems have unique electronic properties and have a broad profile of biological activity: hybrid selenium containing nano-composites are used as an adsorption matrix for highly sensitive immunoassay diagnostic kits, as binding adsorbents for pharmaceutical and cosmetic industries and also in antiseptic and anti-cancer drugs and drugs compensating micronutrient deficiency in the body.

This work was devoted to synthesis and investigation of nanoparticles of zero-valent amorphous selenium (Se0) morphology on the basis of the polyelec-trolyte complexes of the cation copolymer P(VP-K) of N-vinylpyrrolidone (VP) and N,N,N,N-iodide triethylmethacryloyloxyethylfmmonium (K)with sodium dodecylsulphate (SDS). Synthesis of selenium containing nanosystems was per-formed by recovery selenious acid ascorbic acid in aqueous medium, according to the reaction:

H2SeO3+ 2C6H8O6 → Se0+3H2O+ 2C6H6O6 The study of the morphology of the surface of thin films prepared from aque-

ous solutions of selenium containing nanosystems deposited on the surface of silicon was performed by atomic force microscopy (AFM) instrumentation Solver Pro-M and Ntegra Aura («NT-MDT», Russia). Series of samples were investigated with different parameters of polyelectrolyte complexes and the concentration of selenium in solution. A comparison of the results and analysis of the effect that selenium concentrations and parameters of the polyelectrolyte complex have on the morphology of nanosystems.

50

Mn2+ intracenter luminescence study in the heterostructures with ultra-thin MnTe layers

[email protected]

Scientific supervisor: Dr. Serov A.Yu., Department of Solid State Physics, Faculty of Physics, Saint-Petersburg State University

Currently theheterostructures, included ultra-thin layers of different composition with magnetic component are in focus of interests of variousresearches. This kind of samples allows uson the one handto analyze the deferens of realgrown structure from the ideal δ- layer. On the other hand- to study the influence of magnetic field on the electron levels of the heterostructure. It is well knownthat this influence is

considerably higher than in samples without magnetic component.

Our study is concerned with the low temperature excitonic and intra-center Mn2+ emission spectra in the deferentintensityof laser pumping. Theheterostructureswith MnTebarriers (with a nominal thickness correspond-ing to one monolayer (ML)) separated by Cd0.5Mg0.5Te with different thick-nesseswerethe objects of investiga-tions. Fig. 1 shows the structure of these samples. The distance between the barriers was varied from 4 to 32 ML in deferent heterostructures.

The task was to study the influence of the sample structure to the spectra on the exciton and intracenterMn2+, luminescence.

Results and conclusions:1) in the luminescence spectra of the samples thebands with linear and non-

linear dependence on the intensity of laser pumpingare observed;2)bands of luminescencewereinterpreted asthe localized exciton and

intracenterMn2+emission;3) comparison of the luminescence spectra of different samples suggests that the

MnTemonolayers arespread and there is the layers overlapping in thesamples;4) overlapping MnTelayers is observed in the samples 4 and 8 ML, while in16

and 32MLsamples overlapping is missed.

Fig. 1. The scheme of structure of the sam-ples on investigation.

51

Synthesis and electronic structure of graphene fabricated with the solid-state carbon source on the thin

film Ni (111) adsorbed on the single crystal graphite (HOPG)

Pudikov [email protected]

Scientific supervisor: Prof. Dr. Shikin A.M., Solid State Electronics Department, Faculty of Physics, Saint-Petersburg State University

Graphene has been attracting scientific interest for almost 10 years, since the moment of its discovery. Graphene has outstanding electronic properties, such as extremely high electron mobility, that make it a very promising material for electronics. There are a number of widely used methods of graphene synthesis: mechanical cleaving, thermal graphitization of SiC crystal, cracking of carbona-ceous gases, but none of them allows to create graphene on insulating substrates, such as SiO2. One of the newest promising methods is the one that uses segregation of carbon atoms through the substrate. This work is devoted to the experimental study of such solid-state source.

Investigations were carried out by photoelectron spectroscopy of core levels (for the study of photoelectron intensity of C and Ni peaks) and LEED (to analyze the crystalline structure of formed systems). Graphene was fabricated on the surface of a thin Ni(111) film, deposited on the single crystal of graphite (HOPG). The source of carbon atoms was the HOPG crystal itself. The electronic structure of graphene and its dependence on the temperature regime were accurately studied in the work. The comparison of the obtained graphene with the one synthesized by other methods showed that the we can really get it with the solid-state source and this idea can be transferred to some insulating substrates in the future experiments.

52

Dynamical Diffraction of Light in Opal-like Photonic Crystals: 1D Spatially Periodic Structure Approximation

Romanenko [email protected]

Scientific supervisor: Prof. Dr. Sel’kin A.V., Department of Solid State Physics, Faculty of Physics, Saint-Petersburg State University

On the basis of the analytical dynamical theory of diffraction, a study is made of the mechanisms responsible for Bragg reflection spectrum formation in the case of one-dimensional (1D) photonic crystals (PhC).

We discuss the model of opal-like PhC characterized by the one-dimensional dielectric permittivity εs(z). For this model the dynamical diffraction theory is considered to describe Bragg reflection spectra of PhC when incident light is either s- or p- polarized. The model proposed is of principal interest because it is closely associated with the previously performed theoretical and experimental studies [1] of opal-like PhCs and allows one to understand in detail why the dynamical theory of diffraction is applicable for PhC with relatively high dielectric contrast.

The main purpose of our study is to elucidate the validity area of the dynamical theory of diffraction, namely, to find as few periods as possible which provide a rather good numerical agreement between the results of the analytical and full-electrodynamic calculations of the Bragg reflection spectra.

The analytical theory is found to describe well the spectra at any thickness of the PhC plate in the vicinity of the single photonic band-gap, even though the thickness is a part of the spatial period of the dielectric function. We demonstrate that this is the case only at the appropriate boundary conditions that have to correspond to appropriate phases of the Fourier amplitudes in the spatial Fourier expansion of the complex-valued permittivity. These phases are unambiguously determined by spatial positions of the front and rear plane surfaces of the 1D PhC plate.

This work was supported by the Saint Petersburg State University Development Program under Scientific Research No. 11.37.23.2011.

References1. Bazhenova A.G., Sel’kin A.V., Menshikova A.J., Shevchenko N.N. // Solid State Physics, v. 49, № 11, p. 2010, (2007).

53

Spin–orbit coupling induced electronic structure of 3 ML Au/W(110) and 3ML Au/Mo(110) surfaces

Rusinova [email protected]

Scientific supervisor: Prof. Dr. Shikin A.M., Department of Solid State Electronics, Faculty of Physics, Saint Petersburg State University

Owing to its importance for spintronics, effects of spin–orbit coupling have been studying intensively in the recent years [1]. The mainly interest are the systems where a spin current can be created and manipulated without using any external magnetic field. This becomes crucial while there is a tendency of miniaturization of modern electronic devices, and the nearest components of the devices may have great influence on each others.

It is known for spin–orbit coupling to manifest itself in two ways. The first is so–called Bychkov–Rashba effect, when the electronic states of two dimensional electron gas become spin split due to the breaking of inversion symmetry of the system by potentional gradient [2]. The second is a surface–localized spin polar-ization of bulk continuum states which is originates from spin dependent reflec-tion of relativistic Bloch waves from potential gradient creating by presence of a surface or an interface [3]. Due to the phase difference of incident and reflected waves, which is defined by spin direction, the beating of spin density occurs and decays into the depth of a crystal. This surface spin polarization is predicted to be strongly antisymmetric relative to Г point of surface Brillouin zone in accordance with time reversal symmetry.

This work is devoted to the experimental investigation of quantum well states in three-monolayer-thick gold overlayers on W(110) and Mo(110). A strong spin polarization QWSs of d character with an almost identical structure for W(110) and Mo(110) was observed, suggesting a weak interaction with the substrate. Contrariwise for sp QWSs the interaction is much stronger, which to a large extent determines their splitting and spin polarization.

ReferencesWolf S. A. et al. // Science 294, 1488 (2001).1. Bychkov Y.A., Rashba E.I. // JETP Lett. 39, 78 (1984).2. Krasovskii E.E., Chulkov E.V. // Phys. Rev. B 833. , 155401 (2011).

54

Combined DLTS/EBIC study of dislocation related electronic states in plastically deformed silicon

Shlyakhov [email protected]


Dislocation-related electronic states (DRES) in the forbidden gap of silicon have been widely investigated by means of deep level transient spectroscopy (DLTS) developed by Lang [1]. The analysis of the previously published results revealed a significant scatter of the DRES-parameters reported by different authors. There are two main reasons of those differences. The first one proposed in [2] is the inhomogeneity of dislocation density and structure on micro- and macroscales in plastically deformed samples. The second one is the field-enhanced thermoemis-sion of the carriers from the states that was found on regular dislocation networks and was interpreted as a giant Pool-Frenkel (PFE) effect due to the dislocations deformation potential [3]. Thus, the contribution of both effects is expected in plastically deformed samples and the question arises how one can be distinguished experimentally.

In our work for the first time we applied the combination of the DLTS and electron beam induced current (EBIC) techniques [4] for investigation of the n-type silicon sample with dislocations introduced by 4-point bending method. EBIC enabled to visualize recombination contrast of the dislocations and re-vealed the presence of the 3-D irregular dislocation network located within SCR. Measurements of the DLTS spectrums revealed the broadened “C-line” peaks, which can be associated with breaking of dislocations periodicity in the SCR. It was found that peaks of “C-line” spectrum were shifted to low temperature region with increasing the applied biases.

Data correlation obtained by DLTS and mapping of EBIC gave the possibility to estimate the inhomogeneity level of the dislocation network that doesn’t exclude the impact of this factor on the rate of the thermoemission.

References1. Lang D.V. // J. Appl. Phys. 45, 3023 (1974).2. Kisielowski C., Weber E.R. // Phys. Rev. B 44 (1991).3. Trushin M., Vyvenko O.F., Mchedlidze T., Kononchuk O., Kittler M. // Sol. State Phenomena, 156-158, 283-288 (2010).4. Leamy H.J. // Journal of Appl. Physics. 53(6), p. R51-R80 (1982).

55

Determination of misfit stresses, curvatures, defects and termomechanical properties of Si-SiC(111)-AlN(0001)-Al1-xGaxN thin-film heterostructure. Ab initio, FEM and

experimental studies

Telyatnik [email protected]

Scientific supervisor: Dr. Kukushkin S.A., Institute of Problems of Mechanical Engineering of RAS, Laboratory of Structural and Phase Transformations in Condensed Matter, Sain-Petersburg

Perspective wide-gap semiconductors with hexagonal lattice (w-AlN, GaN) can be epitaxially deposited on diagonally oriented cubic crystals (Si, 3C-SiC) almost without misfit stresses producing dislocations due to purposeful formation of such defects as vacancies, dilatational dipoles [1], pores, buckles. Thefore the aim is presentation of overall practical investigation of thin film mechanics [2] and crystallography.

Thermal and lattice mismatch strains are determined for mentioned crystals. Anisotropic elastic moduli are averaged over known experimental values and those obtained by first-principle (ab initio) quantum-chemical calculations. Hooke’s law for diagonally oriented cubic crystals is derived using MATLAB matrix symbolic tool. Curvature of thick composite plate caused by varying misfit stress (e.g. compositionally graded AlGaN) is derived through Kirchhoff hypothesis [3]. Percentage of defects at Si-SiC interface causing stress relaxation and layers thick-nesses are measured from temperature dependent plate curvature by Flexus. Also plate curvature was calculated by finite-element method in ANSYS by modelling misfit strains through fictive thermal expansion.

First-principle calculations in ABINIT (implementing DFT method) for differ-ent supercells with vacuum layers allowed to obtain surface energies of crystals in different orientations that is crucial for macroscopic defects formation (e.g. for direction and amount of cracks). Interaction energy between vacancies and sub-stitutional carbon defects in Si are also calculated and compared to that derived from Eshelby consideration [1].

Critical thicknesses of each stressed pseudomorphic layer for formation of dislocations, parallel cracks or buckles with their periodicity are calculated from continual elasticity theory [2]. Mysterious hexagonal buckles instead of cracks on tensile AlN layer are observed by AFM picture and discussed.

References1. Kukushkin S.A., Osipov A.V.// J. Appl. Phys., v. 113, №2, 024909-1, (2013).2. Freund L.B., Suresh S. Thin Film Materials. Stress, Defect Formation and Surface Evolution. - Cambridge University Press, 2003.3. Telyatnik R.S. // Proceedings of 11 International conference “Films and Coatings - 2013”, St.-Petersburg, p. 284, (2013), (in Russian).

56

Characterization of pristine and fluorinated nanodiamonds by X-ray absorption spectroscopy

Zagrebina [email protected]

Scientific supervisor: Prof. Dr. Vinogradov A.S., Department of Solid State Electronics, Faculty of Physics, Saint-Petersburg State University

Because of unique physical properties, nanodiamonds (NDs) are potentially useful material for a variety of applications in medicine, mechanics, biology, elec-tronics, technology of creating and polishing of materials [1, 2]. However chemi-cal inertness impedes the work with the NDs, therefore various types of chemical functionalization, for instance, surface fluorination are used.

Here we present X-ray absorption spectroscopy (NEXAFS) investigation of pristine NDs, which were synthesized using different methods (detonation, high pressure high temperature and shock compression) [2], and their fluorinated deriva-tives (F-NDs). All measurements were carried out at the beamline D1011, MAX-lab (Lund, Sweden). The powders of all samples were rubbed in previously cleaned and ribbed Cu foil in air. The NEXAFS spectra at the C 1s and F 1s thresholds of the NDs and F-NDs were obtained by recording the total and the partial electron yield of the X-ray photoemission. The obtained C 1s and F 1s spectra were analyzed on basis of a comparison with each other and corresponding spectra of reference systems: carbon nanodiscs and fluorinated graphite [3].

As a result it was found that pristine nanodiamonds particles have on surface some amorphous carbon clusters, which are partially oxidized. According to ob-tained C 1s spectra of F-NDs, the surface fluorination removes these clusters and carbon-oxygen groups from NDs surface (possibly, forming volatile compound like CFn). A comparison C 1s and F 1s spectra of F-NDs with corresponding spectra of the fluorinated graphite (CF)n [3] points to similar character chemical bonding between fluorine and carbon atoms and close tetrahedral coordination of carbon atoms in these compounds. Apparently, in the functionalization process the fluorine atoms are bound with surface carbon atoms of NDs and form covalent bonds that are similar to the ones in (CF)n.

This work was supported by the RFBR (Grant nos.12-02-00999 and 12-02-31415) and SPbU (Grant no. 11.38.638.2013).

References1. Krueger A. et al. // Adv. Funct. Mater., v.17, №22, p. 890, (2012).2. Dubois M. et al. // Solid State NMR, v. 11, №40, p.144, (2011).3. Ahmad Y. et al. // J. Phys. Chem. C, (2013).

57

The comparison of different methods of graphene synthesis

Zashikhin Georgy, Pudikov [email protected]

Scientific supervisors: Prof. Dr. Vladimirov G.G., Prof. Dr. Shikin A.M., Solid State Electronics Department, Faculty of Physics, Saint-Petersburg State University

Investigations of graphene monolayer have attracted enormous interest in recent years due to its unusual electro-physical properties and possibility of using gra-phene as a basic element in future nanoelectronics and spintronics. There are many ways of graphene synthesis. For example, mechanical cleaving, carbonaceous gas cracking, thermal graphitization of SiC, etc. Graphene obtained by these methods has different features that depend on the method being used. In this work some of these methods are investigated.

One of the most well-known methods is the carbonaceous gas cracking on the surface of transitional metals (for example, Ni). Electronic structure of this graphene is similar to quasi-freestanding graphene, but is shifted to higher binding energies. Intercalation of some metal monolayers under graphene shifts electronic structure position to the one of the freestanding graphene.

It is more interesting to synthesize graphene on an insulating substrate. For that purpose an attempt to form graphene on thin Ni film deposited on Si substrate was done. However nickel silicide was formed after annealing of this system. The attempt to passivate the appearance of nickel silicide by thin Cu or Au interlayers was also not successful.

Another method of graphene synthesis involves the use of carbonic solid-state source. In this experiment a thin layer of Ni was deposited on the HOPG crystal. Graphene was formed on the Ni surface after annealing of the system. Its electronic structure is similar to the one of graphene on Ni.

Finally, an attempt to synthesize graphene on the thin Ni film on SiC was done. In this experiment the SiC substrate acts as a solid-state source of carbon. Graphene was synthesized on the Ni surface after the annealing of the system.

So, the comparative analysis of graphene synthesis methods was made in this work.

58

Quantum conductance along dislocation networks produced by silicon wafer bonding

Zharinov [email protected]


1D conductive systems attract now a wide interest among researchers due to their particular properties such as peak-like dependence of density of states, quantum conductivity staircase or Coulomb blockade. However, there are only few published papers in this topic where artificially produced samples were investigated [1].

Dislocations are linear defects in crystals that induced local electronic states in semiconductors and are a unique example of natural 1D system that expected to exhibit an enhanced 1D conductivity along their lines. However, up to now the information about 1D dislocation conductance is scant. Recently a new production method of periodical and regular networks of dislocations (DN) in silicon has been developed based on direct bonding of two silicon wafers (for review see [2]).

Recently it was shown that the dislocation networks gave rise to the appearance of broad energy bands in silicon band gap [3] that might be responsible for the dis-location conductance that was reported by Y. Ishikawa [4] who interpreted observed conductance properties as electron tunneling between dislocations. The latter paper stimulated us to perform more detailed investigation of this phenomenon.

By using ion-lithography technique Field Effect Transistors (FET) on the silicon bonded wafer with the thickness of top layer of 200 nm were prepared. We observed enhanced conductivity along dislocation network and that showed perfect periodical oscillation as a function of applied gate voltage. The origin of these oscillations will be discussed at the Conference.

The results were obtained using the equipment of Interdisciplinary resource center for nanotechnology, nano.spbu.ru

ReferencesThornton T.J. // Rep. Prog. Phys. 57(1994), 311-364.4. Reiche M. // Materials Science Forum Vol. 590 (2008) pp 57-78.5. Kolevatov I. et al.// Phys. Status Solidi C 10, No. 1, 20–23 (2013).6. Ishikawa Y. et al. // Appl. Phys. Lett. 88, 073112 (2006).7.

E. Applied Physics

60

Poly(methyl methacrylate) modified by zirconium dioxide nanoparticles

Antipov [email protected]

Scientific supervisor: Dr. Yevlampieva N.P., Department of Polymer Physics, Faculty of Physics, Saint-Petersburg State University

Polymers’ modification by different type nanoparticles widely used for creation of organic- inorganic composite materials in the last decade. Such polymeric ma-terials containing nanosized additives have found application in a lot of modern technologies including nanotechnologies. Method of special processing of the surface of inorganic nanocrystals for their covalent binding with the polymers have been offered not far ago [1]. The polymers modified by covalently linked nano-particles form molecular-disperse solutions, that allows to produce a nice quality polymeric films with the uniformaly distributed nanoparticles in the volume. In the present work a specially processed zirconium dioxide nanocrystals (ZrO2) of ~20 nm the surface of diameter, received by the method of hydrothermal synthesis, were used for the modification of poly(methyl methacrylate) (PMMA). Modified PMMA samples have been prepared by polymerization of methylmethacrylate by two methods: in block and in solution. PMMA-ZrO2 samples were characterized by dynamic light scattering, viscometry and absorbing spectroscopy. It was shown that the average size of zirconium of containing particles is smaller at polymerization in solution than at block polymerization, and exceeds the size of PMMA molecules synthesized in the same conditions without ZrO2. The existence of multiple cou-pling of polymeric chains with ZrO2 surface was established. It is also shown that the absorption spectrum is sensitive to the conditions of synthesis of PMMA-ZrO2 samples. The absorption spectrum of PMMA-ZrO2 sample distinguished the both a synthesis method and a variation in the averaged number of polymeric chains covalently linked to the nanocrystal surface.

References1. Bugrov A.N., Vlasova E.N., Mokeev M.V., Popova E.N., Ivan ’ kova E.M., Al’myasheva O.V., Svetlichnyi V. M. // Polymer Science, Series B. 2012. V. 54. N. 9-10. P. 486-495.

61

The research into the conductivity of a loaded piezoelectic transducer


Scientific supervisor: Dr. Semenova N.G., Department of Radio Physics, Faculty of Physics, Saint-Petersburg State University

Piezoelectric transducers are in demand for important applications and scientific use of piezoelectric ceramics is usually limited to four categories: sensors, genera-tors, actuators, and transducers.

In this paper we studied the complex converter consisting of two circular piezoelectric elements collected in a column and compressed with 2x metal plates and screws. The aim of this paper was to conduct an experiment to investigate the dependence of the maximum conductivity of the different moments of the forces applied to the tightening bolt (the torque), and depending on the frequency of the maximum conductivity in constant torque forces (while maintaining a constant voltage to the converter).

It has been found that when the torque increases the frequency of resonance converter and its conductivity value at resonance. It was found that the value of the conduction and its resonance frequency depends linearly on the magnitude of the torque in the investigated range from 0 to 4.5 kgfm. Also, there is a slight change in the resonant frequency of the transducer loaded when unloading.

Acknowledgments. All the experimental data were obtained in the Laboratory of Nonlinear Acoustics, Department of Radio Physics, St. Petersburg State University.

62

Migration of the radionuclides from nuclear accidents in the forest ecosystem

Merzlaya [email protected]

Scientific supervisor: Dr. Sergienko V.A., Department of Nuclear Physics, Faculty of Physics, Saint-Petersburg State University

Nuclear catastrophes significantly affect the level of the radioactive contamina-tion. The worst accidents occurred at the Chernobyl and the Fukushima nuclear power plants. The result of this was spreading released radionuclides (more then 10 thousand PBq) from discarded nuclear reactor materials around the world.

To investigate the influence of the accidents on the pollution of environment forest ecosystem was studied. In such ecosystem the anthropogenic impact is rather poor, so that enables to research the natural processes of radionuclide migration in the environment and also to inquire into the amount consumed radionuclides with the products of forest by population.

In order to obtain a complete picture of the influence of accidents on radio-activity of the Leningrad region, investigations were carry out using method that consists in measuring environmental objects such as soil, water and different types of biota by semiconductor HP Ge gamma-detector.

The experiments showed that distribution of radionuclides in the ecosystem is not uniform. In particular, the main contribution in the radioactivity is made up by caesium 137Cs from Chernobyl that can accumulate in human muscles. However the radioactivity of 134Cs, which can identify the Fukushima impact, doesn’t exceed 0.3 Bq/kg.

Overall migration of radionuclides in the ecosystem reveals fact that uptake in biological objects is strongly influenced by absorbing nutrients from the soil. Also type and accumulation ability of soil and the depth at which plants get their nutrients are important factors.

For instance, mushrooms have quite high content of 137Cs – about 1100 Bq/kg. So if human’s consumption of fungi is around 10 kg per year, he get dose that equals 0.2 mSv per year. According radiation safety standards [1] maximum permissible annual dose for the population is not over 1 mSv, it means that dose from fungi is under permissible dose, but it makes significant contribution on radioactivity.

References1. Sanitary rules and norms 2.6.1.2523-09 "Radiation safety standards (RSS-99/2009)".

63

Structuring of photosensitive polymer films by Surface Plasmon near fields

Papke Thomas1, Petrov Yuri 2, Mikhailovskii Vladimir2, Vjvenko Oleg2 and Santer Svetlana1

[email protected]

1Department of Experimental Physics, University of Potsdam, Germany 2Interdisciplinary Resource Center for Nanotechnology, Saint Petersburg State University, Russia

We report on structuring of photosensitive polymer films induced by surface plasmon (SP) near fields. In this approach the distribution of near field can be "printed" directly in to the topography of polymer film [1, 3-7]. The photosensitive polymer films are adsorbed on a metal nano-pattern in which the SP oscillations can be generated by irradiation of it with light of appropriate wave length. The nano-pattern in form of nano-grooves are fabricated by atomic force microscope (AFM) [2] and focussed ion beam (FIB) lithography in a silver layer. We have investigated the near field distribution near the nano-grooves as a function of sample geometry. In our experiment we keep constant the size of the single nano-groove and vary the number of them in the grating. The width of the nano-grooves is 200nm and the periodicity is 900nm, while the depth is determined by the thickness of the silver layer to be 60nm. We have found that the nano-groove lattice couples far field in to near field oscillations, that they are standing ways in between the nano-grooves originating from the interference of two counter propagating SP ways. However, the topography change in form of periodic surface relief gratings of 300nm in period has been also found far out of nano-groove lattice. The propagation length of these EM-ways depends on the number of nano-grooves and ranges between 3m and 10m. Here we discuss possible origin of this structuring. The results are confirmed by FDTD simulations.

References1. König T., Tsukruk V.V., Santer S. Controlled Topography Change of Subdiffraction Structures Based on Photosensitive Polymer Films Induced by Surface Plasmon Polaritons. ACS Applied Materials & Interfaces (2013) DOI: 10.1021/am400712r.2. König T., Papke Th., Kopyshev A., Santer S. // Journal of Materials Science, 48 (2013), 3863.3. König T., Santer S. // Nanotechnology, 23 (2012), 485304.4. König T., Sekhar Y.N., Santer S. // J. Mater. Chem., 22 (2012) 5945 - 5950. 5. König T., Sekhar Y.N., Santer S. // Plasmonics, 7 (2012) 535. 6. König T., Santer S. // Nanotechnology, 23 (2012), 155301.7. König T., Goldenberg L.M., Kulikovska O., Kulikovsky L., Stumpe J., Santer S. // Soft Matter, 7 (2011) 4174.

F. Optics and Spectroscopy

66

The effect of the electrolytes on gelation processes in aqueous cysteine–silver nitrate based solutions

Andrianova [email protected]

Scientific supervisor: Dr. Pakhomov P.M., Department of Physical Chemistry, Faculty of Chemical Technology, Tver State University

Low-concentrated supramolecular hydrogels (~0,01%) based on L-cysteine and silver nitrate are attractive model systems for studying the mechanism of self-organization in a highly charged dilute solutions. Hydrogels are a perspective material for application in medicine, cosmetics, sport and etc.

In the present work the influence of various electrolytes on the processes of self-organization in aqueous solutions of the cysteine - silver nitrate (CSS) is studied by dynamic light scattering, transmission electron microscopy, UV spectroscopy and rheological testing methods. Aqueous solutions of sulfates and chlorides of a number of metals (Al+3, Co+2, Cu+2, К+, Mg+2, Mn+2, Na+, Ni+2) are used as initiators of the gelation in CSS, which are led to formation spatial gel network of various kinds. CSS was prepared by mixing aqueous solutions of a given concentration of the initial components at a certain ratio. For this research the initial solution was subjected to diluting of many times for definition of the bottom concentration limit of the process of maturation. The process of gelation is strongly depends on the temperature; with increasing temperature from 15 to 40°C the rate of maturation of CSS is significantly increasing.

It is established that addition of sulfates of the metals into CSS the strongest hydrogels are formed, when at introduction of nitrates gels are not formed, and the introduction of the chlorides of metals less strong gels are formed. It was also found that for each electrolyte there is a critical concentration at which there is a fast formation of the most stable gel. Regulating concentration of electrolyte it was possible to prepare hydrogels with a varied stability over time. Changing of stability of hydrogels by addition of various salts of the metals is explained by a change of the dielectric permeability of the medium.

Work is performed with financial support of the Ministry of Education and Science of the Russian Federation as part of the state task TvSU for SRW per-formance: "Design and development of gel technology of new type as bases of creation of super - high - strength fibers and medicines" (the order No. 2596 from 3.11.2011.).

67

Theoretical Analysis of Mode-Locked Semiconductor Lasers with External Periodic Forcing

Arkhipov [email protected]

Scientific supervisors: Dr. Vladimirov A.G., Dr. Radziunas M., Weierstrass Institute, Berlin, Germany

Passively mode-locked semiconductor lasers as sources of short optical pulses with high repetition rates (of a few to hundred GHz) have various applications in optical telecommunications [1]. These lasers exhibit significant timing jitter which limits the performance of these lasers in a number of applications. For stabilization of the pulse repetition frequency external RF voltage modulation is used. In the present work using a delay differential equation model [2] we study the dynamics of a passively mode-locked semiconductor laser with dual frequency coherent optical injection and external periodic RF voltage modulation (VM) applied to the saturable absorber section (hybrid mode-locking). The width of the locking range, where the output pulse repetition rate is synchronized to the frequency of the external signal is calculated numerically and asymptotically in the limit of the small external signal amplitude. The dependence of the locking range on the model parameters and the frequency of the external signal is studied. We demonstrate that locking range increases linearly with the external signal amplitude. Our numerical simulations indicate that hybrid mode-locking can be also achieved in the cases when the frequency of the external modulation is approximately twice and half of the pulse repetition frequency of the free-running passively mode-locked laser fP [3]. When the frequency of the external modulation is close to fP, 2fP the locking range has the same value. If the frequency of the external signal is close to fP/2 our theory predicts and experiment confirms that locking range is located within a significantly smaller and strongly asymmetric domain. Possible reasons of the hybrid locking range asymmetry are discussed. This asymmetry is related to the dependence of the pulse repetition frequency fP on the mean absorber relaxation rate, which is changing with the growing modulation amplitude of VM in the absorber section.

R.M. Arkhipov would like to acknowledge the support of EU FP7 ITN PROPHET (Grant No. 264687).

References1. Rafailov E.U., Cataluna M.A., Sibbett W. // Nat. Phot. 1, p. 39, (2007).2. Vladimirov A.G., Turaev D. // Phys. Rev. A., v. 72, №3, p. 033808, (2005).3. Arkhipov R. et al. // IEEE Journ. of Sel. Top. in Quant. Electr., v. 19, №4, P. 1100208, (2013).

68

Transient Cherenkov Radiation from a Periodic Resonant Medium Excited by an Ultrashort Laser Pulse

Propagating at Superluminal Velocity

Arkhipov [email protected]

Scientific supervisor: Prof. Dr. Tolmachev Yu.A., Department of Optics, Faculty of Physics, Saint-Petersburg State University

The problem of superluminal motions existence in nature attracts the at-tention of various researchers for rather a long time [1]. A large number of phenomena demonstrating superluminal velocity is well-known in different areas of physics [1]. If charged particle (such as an electron) passes through a dielectric medium at a velocity greater than the phase velocity of light in that medium Cherenkov radiation arises [2]. In optics it is well-known that spots of light can propagate at the superluminal velocity, as it was considered by I.M. Frank, and V.L. Ginzburg [3]. There are spots of light formed by the rotat-ing searchlight at a fairly remote screen, or the illumination of a flat screen with plane wave, where the intersection of the pulse and the screen moves along the screen at the velocity V = c/sinβ > c (β is the angle of wave incidence, c is the velocity of light) [3] and an intersection point of two interfering laser beams which propagates at the velocity V = c/cosα > c (2α being the angle between two interfering waves). Using these spots of light it is possible to realize an optical excitation of a resonant medium at a velocity exceeding that of light c. We consider the Cherenkov-type radiation in the case of periodically modulated string of oscillators (two-level atoms, quantum dots, optical nanoantennas) excited by laser pulse crossing the string in an oblique direction. It is shown that if the velocity of the propagating excitation is greater (lower) then the velocity of light in vacuum c, a new frequency appears in the spectrum of the medium response [4]. This frequency depends on the velocity of excitation, spatial period of oscillator density. Dependence of this frequency on string geometry is investigated. Possible applications of the effect are discussed.

R.M. Arkhipov would like to acknowledge the support of EU FP7 ITN PROPHET (Grant No. 264687).

References1. Malykin G.B., Romanets E.A. // Optics and Spectroscopy, 112, № 6, p. 920, (2012).2. Bolotovskii B.M. // Phys. Usp., № 52, p. 1099, (2009).3. Bolotovskii B.M., Ginzburg V.L. // Sov. Phys. Usp., № 15, №2, p. 184 (1972).4. Arkhipov M.V., Arkhipov R.M., Tolmachev Yu.A. // Optics and Spectroscopy, № 112, №2, p. 243, (2012).

69

Some aspects of the fractional derivatives application in biophysical models

Batalova [email protected]

Scientific supervisor: Prof. Dr. Mikhailov E.F., Department of Atmospheric Physics, Faculty of Physics, Saint-Petersburg State University

Fractional calculus is now widely developed. The correct definition of frac-tional order derivatives and integrals was given; the properties of the fractional dynamics equations were studied. A lot of numerical methods for solving such equations was found.

As a rule, the equations in fractional derivatives describe the fractal structure of the medium [1]. The fractional diffusion equation is controlled an infiltration of the oil through a porous media, the diffusion through the nuclear membrane, the dissolution of contaminants in groundwater, the relaxation of the protein mol-ecules, and so on.

From diffusion-type equations with fractional time derivative follows a power law dependence of the mean square distance on the time, with an exponent dif-ferent on ½. Experiments conducted with the proteins, in which monomers have a donor-acceptor bond, show that the relaxation of the protein is carried out as the subdiffusion with Hurst exponent ¼. In our work, the addition of an effective repulsion between the monomers leads to a decrease of this exponent [3].

The finding of exact solutions of the fractional diffusion equations, including nonlinear, can be used in estimation of such important value as period of a passage through the shell of the cell nucleus of a transport protein (importin). The diffusion through pores in it is described by fractional differential equations. These studies were carried out previosly [4], and by introducing into the cell quantum dots the sizes of pore in the nucleus (55 nm width, length 68 nm) were prepared and the presence of a narrowing in the pore was explored.

References1. Nigmatullin R.R. // Teoret. Mat. Fiz., 90:3 (1992), 354–368 2. Min W., Luo G., Cherayil B.J., Kou S.C., Xie X.S.// Phys. Rev. Lett., 06/2005; 94(19):198302.3. Batalov L., Batalova A. // Physica A, Vol. 392, pp. 602-611 (2013).4. Lowe A.R., Siegel J.J., Kalab P., Siu M., Weiskweis K., Liphardt J.T. // Nature. Doi:10.1038/nature09285 (2010).

70

Computer simulation of nonlinear dynamics of two charged particles on a circle

Borovykh [email protected]

Scientific supervisor: Dr. Zhuvikin G.V., Department of Optics, Faculty of Physics, Saint-Petersburg State University

The problem of this research is to consider the dynamics of the system of interacting charged particles, constrained to move along a circle. Such system is a

prototype model in nonlinear dynamics of various problems of quantum as well as classic mechanical physics [1, 2].

The classic equations of motion are received in the polar coordinate system [3]. After the separation of the collective variables of the motion the most atten-tion is devoted to the oscillation dynam-ics of the relative angular coordinates of charged particles.

While the angular deviations from the equilibrium position are small, the system is executing harmonic vibrations (Fig. 1).

When the magnitude of the oscilla-tion is rising, anharmonicity takes place and multiple frequencies appear in the oscillation spectrum.

Thus, movement of each particle is one-dimensional, but being studied mechanical system may be considered as a model nanostructure with lower dimension (1D). Besides the problem of two particles has two degrees of freedom.

In this work the aim were finding period of the oscillating system of two par-ticles, as a function of total energy, and Fourier analysis of nonlinear oscillation’s spectrum.

References1. Cleuren B., Van den Broeck C.,. // Europhys. Lett., 54 (1), pp. 1–6 (2001).2. Chryssomalakos C. , Hernandez H., Gelbwaser-Klimovsky D., Okon E. Wires with Quantum Memory. ArXiv:0804.3158, 2008, -8 p.3. Ландау Л.Д., Лифшиц Е.М. Механика.- М.: Наука, 1965, -204 с.

Fig. 1. The oscillation amplitude increases from top to down.

71

Resonance radiation trapping in free-burning arc inhomogeneous plasma

Kalanov [email protected]

Scientific supervisor: Prof. Dr. Golubosvkii Yu.B., Department of Optics, Faculty of Physics, Saint-Petersburg State University

Free-burning argon arc is a plasma source with strongly inhomogeneous dis-tributions of different plasma characteristics in radial direction. It is connected with high temperatures (up to 30000K) in the center of arc. This heating leads to inhomogeneity in neutral atoms densities and respectively to highly inhomogeneous resonance radiation absorption coefficient.

This situation requires precise solution of radiation transport equation (Holstein-Biberman eq.) taking into account strong inhomogeneity of absorption coefficient.

In the present work this equation is solving for the case of infinite cylinder geom-etry, using spherical coordinates and dividing a cylinder to thin layers. Calculations are performing in C++ program, which allows to solve the equation for discrete number of points, using trapezoidal rule for integration and UV-decomposition method for linear equation system solving.

Results of calculations (resonance atoms densities) are presented below in Fig. 1 in comparison with calculus where radiation transport is not taken into account.

Fig. 1. Resonance atoms densities (with rad. transport and without) and excita-tion sources.

72

Luminescence of Y3Al5O12:Eu3+ nanoparticles prepared by modified Pechini method

Kolesnikov Ilya, Tolstikova [email protected]

Scientific supervisor: Prof. Dr. Pulkin S.A., Department of General Physic I, Faculty of Physics, Saint-Petersburg State University

Phosphors are well known materials due to their utilization in wide range of application: displays, traditional lighting devices (cathode-ray tubes, fluorescent lamps, light emitting diode, field emission displays), and biological labels. Recent progress and future prospects show that, luminescent materials remain not only interesting from a scientific perspective but also relevant from an applicative point of view.

Nowadays europium doped yttrium aluminate phosphors (YAG:Eu) can be prepared by different ways like sol–gel, co-precipitation, pyrolysis, combustion or solid state reaction. Most of them are complex and require expensive equipment. One of the most inexpensive and convenient method for synthesis is Pechini method but its disadvantage is strong agglomeration of derived nanocrystalline powders. The modification of the Pechini method – using of additional thermal treatment procedure in molten salt – allows diminishing the agglomeration process.

The main purpose of the present work is to study luminescent properties of nanocrystalline YAG:Eu powders synthesized by modified Pechini method. Also we investigated concentration effect on the lifetime of the excited level of euro-pium ions (5D0).

Luminescent spectra of YAG:Eu nanophosphors were recorded with a fluo-rescence spectrometer Fluorolog-3 with a Xe-arc lamp (450W power ) and the decay curves were obtained with the same spectrometer with a Xe-flash lamp (150W power). The quantum yield was measured using a phosphorimeter’s ac-cessory – integrating sphere Quanta-φ. All the measurements were performed at room temperature.

The emission spectra of YAG:Eu annealed at different temperatures were studied. Spectral lines corresponding to transitions from the excited level 5D0 to the levels 7FJ (J = 1–4). The most intensive transition of the samples sintered at temperatures of 800 and 850oC, is the transition 5D0–

7F2, and of the samples sintered at 900° C and above is the transition 5D0–

7F1.The luminescent decay curves of YAG:Eu phosphors with different Eu3+ concen-

tration by monitoring 709 nm (transition 5D0–7F4) were measured. The experimental

data were fitted to a single exponential function. The dependence of lifetime on doping Eu3+ concentration was investigated.

73

Study of the ‘memory effect’ at breakdown in argon and argon-nitrogen mixture

Korshunov [email protected]

Scientific supervisor: Dr. Meshchanov A.V., Department of Optics, Faculty of Physics, Saint-Petersburg State University

It is known from experiments that the gas discharge can influence the subsequent breakdown for some time after shutdown of the applied voltage. The influence of the previous discharge pulse on the breakdown is a subject of a number of works (see, e.g. [1]) which studied the statistical delay of the discharge pulse relative to the moment of applying the voltage to the electrodes. In these studies short discharge gaps (~ 1 mm) were investigated. To describe this phenomenon the term "memory effect of the discharge gap" was used.

The purpose of this work is to study the breakdown in a long discharge tube (75 cm) filled with argon or argon-nitrogen mixture at low pressure.

In experiment pairs of pulses were used with varied interval between the pulses of the pair. The pair repetition frequency was 1 or 2 Hz. Current and voltage signals in the first and second pulses were registered with the oscilloscope and then pro-cessed on the computer. For optical measurements two optical fibers connected to the PMT were used. The data obtained proved the existence of the memory effect which was manifested as an influence of the time gap between the pulses of the pair on the breakdown voltage of the 2nd pulse. For small delays the breakdown voltage in the 2nd pulse was substantially lower than in the 1st one (Fig. 1). Besides, statistical scatter of breakdown voltage of the 2nd pulse became negli-gible. Addition of nitrogen to argon did not lead to qualitative changes.

Also modeling calcula-tion of plasma in a pulse and after its termination has been carried out. Some conclusions are drawn on the physical reasons of the observable phenomena.

References1. Pejovic M.M., Ristic G.S., Karamarkovic J.P. // J.Phys. D: Appl. Phys. 35, R91-R103, (2002).

Fig. 1. Ar, 1 Torr, 2 Hz, 10 mA.

74

Detailed ultrafast transient absorption study of CuCl42-

complex in acetonitrile

Mereshchenko [email protected]

Scientific supervisor: Dr. Tver'yanovich Yu.S., Faculty of Chemistry, Saint-Petersburg State University

In this work, we reported detailed description of the ultrafast dynamics of a CuCl4

2- complex in acetonitrile upon excitation into all possible Ligand Field (LF) states due to transitions between d-orbitals of the Cu2+ ion, and two most intense Ligand-to-Metal Charge Transfer (LMCT) transitions. The LF states are found to be nonreactive states, while excitation into the LMCT states leads to the ionic dissociation of CuCl4

2- complex.Upon 2000 nm excitation, CuCl4

2- complex was promoted into the lowest ly-ing 2E LF excited state. Vibrational relaxation of the CuCl4

2-complex in 2E state finishes within the first 500 fs, and is followed by internal conversion to the 2B2 ground state with a lifetime of about 1 ps. Excitation of the CuCl4

2-complex into the 2B1 LF excited state upon 1500 nm excitation results in its fast relaxation into the 2E state in less than 50 fs, which then relaxes to the electronic ground state.The 2A1 LF state of the CuCl4

2-complex is formed upon 1100 and 1300 nm excitation directly relaxes to the 2B2 ground state with a lifetime of about 5 ps, in contrast to the 2B1 state, which nonradietively decays to the ground state cascading through the intermediate 2E state. Vibrational relaxation of the CuCl4

2-complex in 2A1 LF state finishes within first 800 fs. Internal conversion dynamics of the LF excited states was explained using the energy gap law approach in the strong coupling limit.

In our experiments, CuCl42- complex was also excited into 2ECl(n) → Cu(dxy) and

2ECu-Cl(π ,σ) → Cu(dxy) LMCT states using 420 and 310 nm excitation wavelengths, re-spectively. After formation, 2ECl(n) → Cu(dxy) LMCT state undergoes internal conversion to the lower-lying vibrationally hot LF excited states, which then either nonradia-tively decay to the ground state, or undergo Cu-Cl ionic bond dissociation, forming CuCl3

- and Cl- ions. These species do not recombine until the longest measured time delay, 1 ns. The 2ECu-Cl(π ,σ) → Cu(dxy) LMCT state undergoes internal conversion to the lower-lying vibrationally hot LF excited states within 300 fs cascading through the lower-lying LMCT states, and Cu-Cl ionic bond dissociation. The vibrational relaxation of formed LF states takes about 5-7 ps, and more than 10 ps for excitation into 2ECl(n) → Cu(dxy) and 2ECu-Cl(π ,σ) → Cu(dxy) LMCT states, respectively. The observed vibrational relaxation is due to energy transfer to acetonitrile, and a higher photon energy correspond to a higher degree of vibration excitation, and, as a result, longer vibrational cooling. The lifetimes of the formed vibrationally hot 2A1 and 2E LF states are similar to the lifetimes of these LF states resulted from direct excitation, which contain much smaller vibrational energy excess.

75

Experimental study of electrical breakdown in a long discharge tube

Oleinik Yuriy, Shishpanov [email protected]

Scientific supervisor: Dr. Ionikh Y.Z., Department of Optics, Faculty of Physics, Saint-Petersburg State University

The work is devoted to the study of electrical breakdown in a long discharge tube, such that its length is much larger than the radius. The tube was 40 cm length and 2.8 cm i.d. Similar tubes are often used in various applications. Interest in the study of breakdown in systems of this type is caused by not only a practical use, but also a lack of information about the breakdown mechanism.

The study was conducted in two different gases - nitrogen and helium at pressure of 1 Torr and at different rates of increase of the voltage applied to the electrodes. We used two different circuit of the discharge switching, one of which made it possible to obtain sufficiently sharp leading edge of the applied voltage pulse, and the second one gave a linearly increasing voltage. It is found that in all cases, the breakdown was preceded by ionization wave propagating from the high-voltage electrode (anode) to the low-voltage. Both low-speed and high-speed ionization waves were observed.

The work is focused on the measurements of the dependence of wave velocity on the breakdown voltage. Measurements were carried out at a fixed power supply voltage, which was equal to 3.6 kV for research with nitrogen and 3 kV for the measurements in helium.

Technique of simultaneous measurement of the wave velocity and the break-down voltage was applied. A digital oscilloscope, two optical fibers, and the photomultiplier were used. For given conditions, sample of 50 measurements was recorded.

It is found that the ionization wave velocity in a wide range of the voltage rise rate correlates with the breakdown voltage and does not depend on the volt-age rise time. For nitrogen an increase in voltage rise rate leads to normalizing breakdown by reducing the scatter of the moments of breakdown. Also it results in reducing the minimum value of the breakdown voltage. The average value of the breakdown voltage in nitrogen depends on the steepness of the pulse leading edge not-monotonically, reaching the minimum at ~500 V/ms. The average speed of the ionization wave increases with the voltage rise rate.

76

Study of the unique copper-containing biomineral from endemic Baikal Lake sponges by synchrotron radiation

Petrova Olga [email protected]

Scientific supervisor: Prof. Sivkov V.N., Laboratory of Theoretical Physics, Mathematic Department, Komi Science Center of the Ural Division of the RAS

The investigation of chemical structure peculiarities and identification of mineral and organic constituents within nanostructured biocomposites is a challenging task in modern material science. Recently, the blue colored endemic sponges from Baikal Lake, which synthesized unknown copper-based biomineral were discovered. In the previous investigations we find that blue colored sponges contain Cu-biomineral grown only on the protein nano-fibers which together with siliceous spicules form the skeleton of the sponge. Besides we suggest that copper atoms within this copper-containing biomineral have bivalent as well as monovalent character and interact with protein side chain nitrogen atom [1]. But the mechanism of Cu-bonding in this structure is still unknown.

The main aim of present research is investigation of Cu-bonding mechanism within this unique copper-based biomineral by NEXAFS and XPS spectros-copy [2].

During this investigation we carry out NEXAFS and XPS studies (Cu2p-, C1s- and N1s- spectra) of copper-phosphate biomineral from endemic Baikal Lake sponge, Cu3(PO4)2and synthesized Cu3(PO4)2–histidine system in additional to recently investigated Cu-containing minerals and benchmark compounds [1]. All NEXAFS-spectra were measured in total electron yield (TEY) mode at synchrotron source BESSY II using radiation from the Russian-German dipole beamline.

The present research show that blue-colored sponge contain protein included anion [PO4]3- in the form of Cu3(PO4)2. Furthermore the blue-colored sponge Cu-atoms have bivalent as well as monovalent character within Cu3(PO4)2+histidine complex composite and do not interact with peptide group atoms. In these case Cu and histidine interaction are provided by deprotonate N-atoms of histidine side chain imidazole cycle. Also the Cu3d and histidine side chain imidazole cycle π*orbitals are formed hybridized state in this composite.

References1. Petrova O.V. // Book of Abstracts 2012 of the International Student Conference "Science and Progress" 12-16.11.2012, Saint-Petersburg, Peterhof, Russia. 2. Stöhr J. NEXAFS Spectroscopy, Springer: Berlin, 403 (1992).

77

Study of instrument function of optical digital spectrograph

Savinov [email protected]


At present one of ways of atomic emission spectrum analysis development is the improvement of registration system. At last decade photodiode detectors which can be easily assembled in spectrum devises and allow to combine advantages of photographic way of registration and photoelectric way of photometric measure-ments became widespread in our country. Spectrum recording and processing of information are based on digital technology, that is why these modernized devices became digital spectrographs and direction of their usage in optical spectroscopy can be named as “atomic emission digital spectrography”.

Because of it specificity digital registration reveals a number of possibilities of instrumental parameters optimization, particularly, allows to detect changing of luminous flux on a profile of a spectral line, width of which is about several photodiodes. This fact permits to research the influence of width of entrance slit on a shape of spectral line and to determine optimal parameters of spectral device for obtaining better metrological characteristics. The study were carried out with spec-tral device MFS-8 and photodiode linear detector MAES (VMK-Optoelektronika, Novosibirsk), which registers spectrum in a range 197-343 nm.

The report contains results of experimental research of instrument function and practical resolving power of digital spectrograph. It was established that when width of entrance slit increases from 3 to 100 µm, instrument function keeps bell-shaped shape with maximum in the middle. Experimentally determined values of practical resolving power steadily grow when width of entrance slit decreases from 90 to 10 µm, and then remain constant when width are 6 and 3 µm. It was discovered that increasing of width results in proportional growth of spectral line intensity and this growth isn’t limited on top.

78

Effect of F-doping on photocatalytic activity of titania

Shaytanov [email protected]

Scientific supervisor: Prof. Ryabchuk V.K., Department of Photonics, Faculty of Physics, Saint-Petersburg State University

In present the studies in the area of heterogeneous photocatalysis attracts a great interest from both fundamental and application points of view. One of the major issues in this area is an increase of the activity of photocatalyst, particularly through extension of the spectral region of photocatalyst activity toward visible light. The promising pathway to achive the higher spectral sensitivity of photocatalysts is a formation of intrinsic and extrinsic defects absorbing the visible light. Over the last decade titania, doped with various non-metals was actively studied. However, the activity of doped photocatalysts is not significant.

In our work fluorine was used as a dopant. The aim of our work is an experi-mental studies of the alteration of photoactivity of TiO2 caused by fluorine doping. Accordingly, we studied the activity of F-doped TiO2 with respect to oxygen and hydrogen photo-adsorption, and examined the alteration of the efficiency of color centers photogeneration in vacuum and in presence of the gases (oxygen and hydrogen) by diffuse reflection spectroscopy. Tested samples were F-doped TiO2, with concentrations of fluorine 0,1; 0,5; 1; 2 % wt, and pristine TiO2 as a refer-ence sample. All samples have been prepared in laboratory of Prof. Rose Amal, (University of New South Wales, Sydney, Australia) by flame spray pyrolysis.

As a major results, the influence of photostimulated adsorption of donor and acceptor gases on defect formation has been demonstrated. According the spectro-scopic data can be one can conclude that for the same types of defects are formed at the surfaces of both nominally pure and F-doped titanium dioxide, that is F-doping of titania does not result in formation of new type of the defects. Photostimulated adsorption of hydrogen leads to the formation of electron-type centers with char-acteristic absorption in the region of 600 - 900 nm that can interact with oxygen. Dependence of the lifetimes of the electron and hole centres on the fluoride con-centration was obtained. More detailed results are given in the presentation.

The author expresses his gratitude for the help in carrying out the experi-ments and examination of the obtained spectra to his scientific supervisors Prof. V.K. Ryabchuk and Prof. A.V. Emeline.

79

Effect of the shape and orientation of filler particles in polymer materials on scattering studied by IR spectroscopy

Sitnikova [email protected]

Scientific supervisor: Dr. Pakhomov P.M., Department of Physical Chemistry, Faculty of Chemistry, Tver State University

For characterization of the structure of composite or porous materials and polymer blends the shape and orientation of the filler particles have to be taken into consideration. Only microscopic techniques are suitable for nondestructive estimation of filler aggregates shape. Previously, by using the IR spectroscopy particle size of the filler investigated with the assumption that the particles are in polymeric matrix spherical or close to this form. However, in the case of composites filled with various fibrous filler excipients shape is far from the ideal case.

The aim of this work is the study of effect of the shape and orientation of filler particles in polymer materials on scattering in IR spectra.

As research objects have been taken polymer composite materials based on polypropilene (РP) filled by anisotropic particles of carbon nanofiber (CNF) with length of 15 μm and diameter of 150 nm.

The spectra of the composites of PP / CNF were recorded on an FTIR spectrom-eter «Equinox 55» using 5 different ways. The spectra of the films were recorded at the rotation towards 0°, 45°, 90° to the direction of extrusion, as well as at the rotation of the sample from the normal towards 45 ° relative to the incident radia-tion. Estimation of aggregate size CNF performed using spectroscopic methods for determining particle sizes of fillers in the polymer matrix [1].

According to the geometrical representations, in the case of spherical particles there is no change in the size of their cross section under rotating the sample, and in the case of cylindrical is increase (or decrease) in the cross section of the particles is proportional to the cosine of the rotation angle about the axis of the film.

The presence (or absence) of change in the average particle diameter due to the rotation plane of the film at different angles from the normal position (with respect to the incident radiation), speaks about anisotropy (or isotropy) particles in the polymer sample. Conclusions about the orientation of the filler particles in the film can be drawn after analyzing changes of their sizes under rotation of the films at different angles.

Thus, the method of IR spectroscopy can be used to identify orientation and shape filler particles in the polymer matrix.

References1. Malanin M.N., Pakhomov P.M., Khizhnyk S.D. Patent RF. №2393458 27.08.2008.

80

Design of a high definition monochromator

Solovev [email protected]

Scientific supervisor: Dr. Davydov V.G., Department of Photonics, Faculty of Physics, Saint-Petersburg State University

Resonant raman scattering is a powerfull technique for investigation of such systems GaAs, GaAlAs or InGaAs. The wavelength of resonant exciton transi-tion for these systems is about λ≈800 nm. Therefore, to study these system a high definition monochromator is required [1]. However, commercial devices aimed at non-resonant raman scattering of the homogeneous solid, where intensity is lower and frequency is higher than in the systems we study. This fact causes the degradation of spectral resolution and it means these devices are not applicable for semiconductor nanostructures.

The aim of the present work is to design a high definition monochromator. It means a significant decrease in inverse linear dispersion over a monochromator MDR-23 that equals ∂

∂=

λl

nmmm

1 3. .

We used optical design and analysis software “Beam Four Optical Ray Tracer” to model different optical schemes of monochromators.

We have found out that the scheme with a lens collimator (Fig. 1) results in decrease in inverse linear dispersion in 2 times and equals

∂∂

≅λl

nmmm

0 47,

while the area of monochromatic spot is less than 1 mcm2. Thus the results allow us to assume that the development of this design will have a positive effect in the study of GaAs structures.

References1. Zaidel A.N., Ostrovskaya G.V., Ostrovsky Y.I. Technics and practice of spec-troscopy”. – Moscow: Fizmalit,1972.

Fig. 1. Scheme with a three-surface lens.

81

Two-photon transitions with cascades and two-photon level widths

Zalialiutdinov [email protected]

Scientific supervisor: Prof. Dr. Labzowsky L. N., Department of Quantum Mechanics, Faculty of Physics, Saint-Petersburg State University

An ambiguity of separation of cascades from "pure" two-photon decay is confirmed with accurate numerical calculations in a gauge-invariant way. A direct evaluation of two-photon decay width of excited states in H-like ions via imaginary part of two-loop self-energy is presented. We demonstrate that there is fundamental difference between the level width and transition probability in the presence of cascades. The two-photon widths are shown to be different from the two-photon decay rates for the transitions including cascades.

We investigate the problem of the evaluation of the two-photon level width via the imaginary part of two-loop electron self-energy. This evaluation was performed in a series of works [1-3] and it was claimed that the results obtained present an unambiguous way to evaluate the "pure" two-photon contributions to the two-photon transitions with cascades. The derivations were made non-relativistically. The numerical values differ essentially from the ones in [4]. In the present work we rederived the imaginary part of the two-loop contribution in a fully relativistic way and confirmed exactly the results [1-3]. However we argue that these results have no direct connection to the two-photon decay rates for the transitions with cascades as it was claimed in [1-3]. The numbers obtained in [1-3] and confirmed in our present work are the "pure" two-photon contributions to the level widths which are always smaller than the one-photon contributions. They represent small corrections to the total level widths. Moreover, these contributions can be even negative what confirms our treatment of these contributions.

References1. Jentschura U.D. // J. Phys. A40, F223-F227 (2007).2. Jentschura U. D. // J. Phys. A41, 155307 (2008).3. Jentshura U.D. // Phys. Rev. A79, 022510 (2009).4. Labzowsky L., Solovyev D., Plunien G. // Phys. Rev. A80, 062514 (2009).

82

Verification of two independent models for spectroscopic determination of the H2, HD, D2 partial densities in non-

equilibrium hydrogen-deuterium plasmas

Zhukov [email protected]

Scientific supervisor: Prof. Dr. Lavrov B.P., Department of Optics, Faculty of Physics, Sankt Petersburg State University

Isotopologues of diatomic hydrogen (H2, HD, D2) are widespread in Nature, Science and Technology. Models under the study are based on two groups of simple assumptions concerning electron-impact volume dissociation of molecules and as-sociation of atoms on surrounding metal walls (model 1), and excitation-decay of molecules within low density non-equilibrium plasma (model 2). Two independent groups of experimental data are used as sources of experimental information: rela-tive intensities of Balmer lines of hydrogen and deuterium atoms (model 1) and relative Q-line intensities of Fulcher-α bands (model 2). It should be stressed that both models are totally free from adjustable parameters.

For experimental verification of models we measured emission spectrum of plasma inside cylindrical molybdenum electrode introduced between anode and cathode of glow discharge in hydrogen-deuterium mixtures. High-resolution digital spectrometer [1] have been used for the intensity measurments. As an example, the relative particle densities (which easily may be recalculated into partial densities) obtained for one particular discharge conditions (deuterium with small hydrogen impurity under the pressure 6 Torr, and current density 0,4 A/cm2) by means of the models are presented in the following table, the experimental errors (one SD) transposed to final results are shown in brackets in units of least significant digit:

Relative particle densities Model 1 Model 2

[H] / [D] 0.054(5) -

[H2] / [D2] 0.0041(8) 0.0034(4)

[HD] / [D2] 0.066(6) 0.050(7)

One may see that in our conditions the results obtained by two independent mod-els are in rather good mutual accordance. Thus it is shown that both models could be used for determination of the H2, HD, D2 partial densities in non-equilibrium hydrogen-deuterium plasmas. This technique obviously could be generalized for including T2, HT and DT molecules.

Present work is supported, in part, by RFBR (the Grant #13-03-00786a).

References1. Lavrov B.P. et al. // J. Opt. Technol., v. 78, I. 3, p. 180, 2011.

G. Theoretical, Mathematical and Computational Physics

84

Long-range rapidity correlations in a two-component model

Andronov [email protected]

Scientific supervisor: Prof. Dr. Vechernin V.V., Department of High Energy and Elementary Particles Physics, Faculty of Physics, Saint-Petersburg State University

The long-range correlations between the multiplicities (n) and the event mean transverse momenta (pt) of charged particles in two windows separated in rapid-ity in the multiparticle production in pp and AA collisions at high energies are analyzed in the framework of the model with two types of independent emitters [1] (or, “independent seeds” [2]). Primary emitters are produced immediately in collision and the secondary - after interaction of some of the first ones. The simple toy model which reproduces the mechanism of emergence of secondary emitters is suggested.

The dependencies of n-n and pt-n correlations on the interaction parameter of primary emitters and on the average number of primary emitters were studied. It was shown that with the increase of interaction parameter both the increase and the decrease of n-n correlation strength are possible.

The possibility of experimentally observed [3] negative pt-n correlation is discussed. The obtained analytical results were also tested by the Monte-Carlo simulations.

References1. Vechernin V.V. // Proc. of Baldin ISHEPP XX, Volume II, 10 (2010); arxiv:1012.0241v1 (2010).2. E. Sicking on behalf of the ALICE Collaboration // CERN LHC Seminar “Multiple Parton Interactions in ALICE” 05-03-13 https://indico.cern.ch/getFile.py/access?resld=0&materialld=slides&confld=238569.3. Feofilov G.A., Kolevatov R.S., Kondratiev V.P., Naumenko P.A., Vechernin V.V. // Proc. Of Baldin ISHEPP XVII, Volume I, 222 (2005).

85

The renormalization of spin-wave spectrum in three-dimensional antiferromagnetic with dipolar interaction

Batalov [email protected]

Scientific supervisor: Dr. Syromyatnikov A.V., Theoretical Department, Petersburg Institute of Nuclear Physics, NRC "Kurchatov Institute"

The subject of my research is the phenomenon of the spin waves in the three-dimensional antiferromagnetic with a cubic lattice. The microscopic Hamiltonian consists of the exchange (short-range) and the dipole (long-range) interactions. The main value computing by us is the spectrum of elementary excitations - magnons. Its real part gives the magnon energy, and the imaginary part gives the inverse lifetime of the magnon. The topic is of interest nowadays because in recent times in magnetically ordered crystals is observed quite unusual properties. Here are some of them.

First, the classical energy of the isotropic ferromagnetic is infinitely degenerated in the direction of the magnetization. Some of the directions, however, may be allocated at the finite temperature [1]. Quantum fluctuations can remove this degeneracy also. In the present case the dipole-dipole interaction gives such effect.

Second, the well-known spectra of the isotropic ferromagnets and antiferromag-nets are gapless, and the presence of dipole forces leads to appearence of the gap in the spectrum, which is greatly renormalized in the long-wavelength range [2].

Thirdly, the theoretical studies show that in the two- and three-dimensional ferro-magnets with the dipolar forces at temperatures much lower than the critical one there is the region of momenta, where the inverse lifetime of the magnon is a few tenths of its energy [3]. This effect is caused primarily by the processes of an compounding and makes magnons badly defined in a certain range of wave vectors.

From all these suggests we can conclude that the adding to the Hamiltonian of the long-range dipole forces (despite their smallness) significantly changes the structure of the spectrum. In recent years we have an experimental possibility to verify the above features. In 2011 by neutron spectroscopy the lifetime of the magnon with extremely short momenta in the crystal antiferromagnetic MnF2 had measured [4]. Further experiments can confirm the statement about the existence of the range of the wave vectors, where the magnons has strong damping.

References1. Henley C.L. // Phys. Rev. Lett. 62, 2056 (1989).2. Syromyatnikov A.V. // Phys. Rev. B 77, 144433 (2008).3. Syromyatnikov A.V. // Phys. Rev. B 82, 024432 (2010).4. Bayrakci S.P. et al. // Science, vol. 312, p. 1926 (2006).

86

Some aspects of the fractional derivatives application in biophysical models

Batalova [email protected]

Scientific supervisor: Dr. Mikhailov E.F., Department of Atmospheric Physics, Faculty of Physics, Saint-Petersburg State University

Fractional calculus is now widely developed. The correct definition of frac-tional order derivatives and integrals was given; the properties of the fractional dynamics equations were studied. A lot of numerical methods for solving such equations was found.

As a rule, the equations in fractional derivatives describe the fractal structure of the medium [1]. The fractional diffusion equation is controlled an infiltration of the oil through a porous media, the diffusion through the nuclear membrane, the dissolution of contaminants in groundwater, the relaxation of the protein mol-ecules, and so on.

From diffusion-type equations with fractional time derivative follows a power law dependence of the mean square distance on the time, with an exponent dif-ferent on ½. Experiments conducted with the proteins, in which monomers have a donor-acceptor bond, show that the relaxation of the protein is carried out as the subdiffusion with Hurst exponent ¼. In our work, the addition of an effective repulsion between the monomers leads to a decrease of this exponent [3].

The finding of exact solutions of the fractional diffusion equations, including nonlinear, can be used in estimation of such important value as period of a passage through the shell of the cell nucleus of a transport protein (importin). The diffusion through pores in it is described by fractional differential equations. These studies were carried out previosly [4], and by introducing into the cell quantum dots the sizes of pore in the nucleus (55 nm width, length 68 nm) were prepared and the presence of a narrowing in the pore was explored.

References1. Nigmatullin R.R. // Teoret. Mat. Fiz., 90:3 (1992), 354–368.2. Wei Min, Guobin Luo, Binny J. Cherayil, S.C. Kou, X. Sunney Xie //Phys. Rev. Lett., 06/2005; 94(19):198302.3. Batalov L., Batalova A. // Physica A, Vol. 392, pp. 602-611 (2013).4. Lowe A.R., Siegel J.J., Kalab P., Siu M., Weiskweis K., Liphardt J.T. // Nature. Doi:10.1038/nature09285 (2010).

87

Equation of state of high density matter in the model of Nambu-Jona-Lasinio


Scientific supervisor: Dr. Gvozdev A.A., Department of Theoretical Physics, Faculty of Physics, P.G. Demidov Yaroslavl State University

High density medium of cold nucleus massive “neutron” star, consisting of quarks, condensate and meson, is investigated in the work. Positing of such task is actual in connection with the existence of neutron stars with masses about or more than two Sun masses.

Density of energy and pressure of cold firm medium as functions of param-eters of model and chemical potential of quark, are calculated in the framework of the simplest model, describing strong interaction between quarks (in the model of Nambu-Jona-Lasinio [1]). Equation of state of given system is received and it turned out to be similar to equation of state in the famous MIT bag model [2]. Unlike the former that kind of equation maintains only two parameters: the four-fermion interaction constant and cut off parameter. This decreases uncertainty in numerical modeling of relation mass-radius of mass “neutron” star.

References1. Nambu Y., Jona-Lasinio G. // Phys. Rev. 122 (1961) 345.2. Chodos A., Jaffe R.L., Johnson K. et al. // Phys. Rev. (1974) V. D9. P. 3471.

88

Streaking of near-threshold photoelectrons produced in laser-assisted attosecond photoionization

Bozhevolnov [email protected]

Scientific supervisor: Kazansky A.K., IKERBASQUE, Basque Foundation for Science, Bilbao; DIPC, Donostia/San-Sebastian, Spain

A drastic modification of the conventional streaking patterns of double dif-ferential cross section (DDCS) for attosecond ionization of infrared (IR) dressed atoms near the ionization threshold is theoretically demonstrated. It is shown that new features can be observed in DDCS for the near-threshold ionization such as interference fringes and strong maxima at small photoelectron energies. They arise when the ejected low-energy electron wave packet is strongly affected by both the ionic core and the IR fields. The computations based on solving the time-dependent Schrodinger equation (TDSE) show that the most interesting and most informa-tive DDCS pattern can be observed when the ionizing attosecond pulse comes at a maximum value of the IR field. Since attosecond pulses with a carrier frequency of ωX ~ 40−50 eV is currently available for experimental studies, investigations of, e.g., subvalence s-shell ionization in noble gases seems to be feasible in the near threshold region. They can provide unique information on low-energy photoelectron dynamics in a strong laser field.

89

Renormalization group analysis of the inertial-range behaviour of a passive

vector field in a random shear flow

Gulitskiy [email protected]

Scientific supervisor: Prof. Dr. Antonov N.V., Department of High Energy Physics and Elementary Particles, Faculty of Physics, Saint-Petersburg State University

The problem of turbulent advection, being of practical importance in itself, has become a cornerstone in studying fully developed hydrodynamical turbulence on the whole. Much attention has been attracted to the problem of intermittency and anomalous scaling in developed magnetohydrodynamic (MHD) turbulence. It has long been realized that in the so-called Alfvenic regime, the MHD turbulence demonstrates the behavior, analogous to that of the ordinary fully developed fluid turbulence: cascades of energy from the energy-containing range towards smaller scales, where the dissipation effects dominate the dynamics, and self-similar (scal-ing) behavior of the energy spectra in the intermediate (inertial) range.

In this work we investigate more general A-model, which combines as special cases MHD (A=1), linearization of the Navier-Stokes equation around the rapid-change velocity field (A=-1) and the model of passively advected vector impurity (A=0) [1]. The external velocity field v(x) obtains the allotted direction [2]:

).,(),( ⊥⋅= xtvnxtv

In the real problem, the velocity v(x) satisfies the Navier-Stokes equation, prob-ably with additional terms that describe the feedback of the advected field. But here we will consider a simplified model where the statistics of v(x) is given: it is a Gaussian field with zero mean and prescribed correlation function.

Infrared asymptotic behavior is studied by means of the field theoretic renor-malization group. The objects of interest are correlation functions of operators, build solely from vector fields itself. It is proved, that in the first order of perturba-tion theory the matrix of critical dimensions is singular, therefore the correlator asymptotic is not pure exponential, but with logarithmic part.

References1. Antonov N.V., Hnatich M., Honkonen J., Jurčišin M. // Phys. Rev. E 68, 046306 (2003).2. Antonov N.V., Malyshev A.V. // J. of Stat. Phys., vol. 146, is. 1, pp. 33-55 (2012).

90

Solution of the time-dependent Dirac equation for the U91+(1s) – U92+ collision with the partial wave expansion

Ivanova [email protected]

Scientific supervisor: Prof. Dr. Shabaev V.M., Department of Quantum Mechanics, Faculty of Physics, Saint-Petersburg State University

Investigations of heavy ions provide a unique tool for tests of relativistic and quantum electrodynamics effects at strong fields [1].

In the present work we have studied the low-energy U91+(1s) – U92+ collision and solved the time-dependent Dirac equation. The target U91+(1s) was at rest at the origin. The projectile U92+ moved along a straight line with a constant velocity V and the impact parameter b. The projectile energy was chosen to be approximately equal to the Coulomb barrier energy that in case of the uranium nucleus amounts to 5.9 MeV/u.

Nowadays a lot of calculations in atomic physics and quantum chemistry are based on finite basis set methods. This work represents the use of the dual kinetic balance (DKB) approach [2] in which the basis functions are constructed from B-splines. The DKB approach provides a solution of the stationary radial Dirac equation without spurious states.

At the first stage the stationary problem for the electron in the Coulomb field of the uranium nucleus has been solved with the DKB approach. At the second stage the time-dependent problem for the electron in the field of two nuclei has been considered. The time-dependent Dirac wave function was expanded in terms of the stationary Dirac equation solutions. The expansion coefficients were defined applying the Crank-Nicolson propagation scheme [3].

Ionization probability and probability of finding the electron in the ground state were calculated for different values of the impact parameters. The partial wave expansion of the bare nucleus potential was used in the work. The results are presented for several terms of the partial wave expansion.

The theoretical data that describe the process under consideration are needed for the experiments at GSI and FAIR, Darmstadt.

References1. Eichler J., Meyerhof W.E. Relativistic Atomic Collisions. New York, Academic Press, 1995.2. Shabaev V.M., Tupitsyn I.I., Yerokhin V.A., Plunien G., Soff G. // Phys. Rev. Lett. 93, 130405 (2004).3. Crank J., Nicolson P. // Proc. Cambridge Philos. Soc. 43, 50 (1947).

91

Splint in case of special embeddings

Kakin [email protected]

Scientific supervisor: Prof. Dr. Ioffe M.V., Department of High Energy and Elementary Particles Physics, Faculty of Physics, Saint-Petersburg State University

The term "splint" was introduced by D. Richter in [1] where classification of splints for classical root systems were obtained. It was shown in [2] that not only splint has tight connections with the injection fan construction but that it can be used as a tool to study reduction properties of g-modules with respect to a subal-gebra of algebra g and, in particular, it allows to drastically simplify calculation of branching coefficients for corresponding reduced modules.

The aim of the present work is to generalize splint on case of special embed-dings. It was found that such a construction can be build and can yield the similar results as splint does in case of regular embeddings. To interpret properties of the new construction superposition of singular elements was used.

A phenomenon of splint is yet mostly unexplored but it might present unex-pected possibilities to discover new properties of singular elements and special embeddings which otherwise are hard to study.

References1. Richter D. // J. Geom. 103 (2012), p.103-117.2. Lyakhovsky V.D., Nazarov A.A. Fan, splint and branching rules. // Arxiv preprint arXiv:1111.6787v2 (2011).

92

Higher order asymptotics and critical exponents in the φ3 theory

Kalagov [email protected]

Scientific supervisor: Prof. Nalimov M.Yu., Department of Statistical Physics, Faculty of Physics, Saint-Petersburg State University

The interaction of the type g𝜑3 is considered in present work. This potential has no local minimum. However, if g is imaginary, then the corresponding Hamiltonian commutes with space-time (PT) reflection operator. A PT-symmetric Hamiltonian often has a parametric region in which the energy eigenvalues are all real. There may also be a region in which some of the eigenvalues are complex. These regions are separated by a phase transition that has been repeatedly observed in laboratory experiments [1].

The critical exponents are calculated in the form of segments of the series ε-expansion. Because these series are asymptotic, various resummation schemes, such as the Borel–Leroy method, the Pade’ approximation technique, and the technique of conformal mappings, have been used to obtain numerical values of exponents in actual space dimensions. For these purposes, information about the higher order asymptotics (HOA) of quantum-field perturbations theory in the model is required.

Investigations of the HOA of the perturbation theory series is based on the saddle-point expansion of a functional integral proposed in [2]. Following [2] for the theory of type φ2n the N-th term of a standard field-theory expansion of a quantity G in powers of the coupling constant g expressed through Green’s func-tions at large N is

Here, we let G(N) denote the coefficient of gN in the g expansion of a quantity G.

The main priority of our work is determination of the HOA expansions of renor-malization constants and critical index η in the 𝜑3 theory, and comparison of the currently known terms of the ε- expansion with the found asymptotic. In the result of the analysis it’s established that the perturbation theory series are asymptotic in the φ3 theory and can be resummarized according to Borel. The results of resumma-tion η with use of various schemes are provided in the work. Our results show that calculated for today orders of expansions of renormalization constants are still far from the Lipatov's asymptotic, and accuracy of the critical index calculations are not so high even after the Borel resummation. However, note that using informa-tion about HOA, nevertheless, reduces the error of calculations.

References1. Bender C.M., Messina E. // Phys. Rev. D, v. 85, 085001 (2012).2. Lipatov L.N. // JETP, v. 72, p. 411, (1977).

93

Effective models for the radial Regge trajectories

Katanaeva [email protected]

Scientific supervisor: Dr. Afonin S.S., Department of High Energy and Elementary Particles Physics, Faculty of Physics, Saint-Petersburg State University

The spectrum of radially excited hadrons proves to be a fruitful source of in-formation about the confinement forces in Quantum Chromodynamics (QCD).

The confinement is widely realized in terms of the QCD string concept which is exploited as the idealized description of quark systems. The usual models based on the QCD string possess an apt basic feature: the linear Regge recurrence, m2

J J (J denotes the hadron spin), emerges already on the classical level of rotating string. However, the radial modes appear after quantization. That seems to be unacceptable as the consistent theory of quantized QCD string has not been built in spite of extensive efforts.

The aforementioned problem gives rise to the development of alternative dy-namical approaches with the linear radial spectrum naturally appearing. We put forward [1] some effective field models in which the hadrons acquire masses due to interaction with a scalar field modeling the non-perturbative gluon vacuum. The effective potential for this field is periodic with an infinite number of non-equivalent vacua. The radially excited hadrons emerge as elementary excitations over different vacua. The models discussed should be viewed as effective models for QCD in the large-Nc limit (because the number of resonances is infinite and the zero-width approximation is implied). They are complementary to the usual effective field theories for the strong interactions (the sigma-models, chiral per-turbation theory, etc).

Another peculiarity of the considered models is the existence of a classical field configuration in each vacuum. Depending on the model it can represent a domain wall, Nielsen-Olesen vortex or 't Hooft - Polyakov monopole.

The analysis of the first quantum correction is performed in the pure scalar sector. The splitting of the radially excited modes into two nearly degenerate states takes place on the computational level and also has some phenomenologi-cal support [2].

The presented approach may be also viewed as an alternative framework to the bottom-up AdS/QCD models where the radial excitations appear on the classical level as well.

References1. Afonin S.S., Katanaeva A.D. // Eur. Phys. J. C 73 (2013) 2529. 2. Bugg D.V. // Phys. Rept. 397 (2004) 257.

94

Critical behavior of the O(n)-φ4 model with an antisymmetric tensor order parameter

Lebedev [email protected]

Scientific supervisor: Dr. Antonov N.V., Department of High Energy and Elementary Particles Physics, Faculty of Physics, Saint-Petersburg State University

Numerous physical systems reveal interesting singular behavior in the vi-cinity of their critical points. Their thermodynamical and correlation functions exhibit scaling behavior with universal critical dimensions: according to general belief, they depend only on a few global characteristics of the system, such as symmetry or dimension. Most typical phase transitions (liquid-vapour systems, binary alloys, ferro- and antiferromagnets) belong to the universality class of the O(n)-symmetric model with quartic interaction (Euclidean φ4 model) with an n-component order parameter. Another important example is provided by the U(n)-symmetric φ4 model with a complex order parameter. This model, describing transitions in quantum gases and liquids, is in fact equivalent to the O(2n)-symmetric real case.

In present work we studied critical behavior of the O(n)- φ4 model with an an-tisymmetric tensor order parameter by means of the field theoretic renormalization group (RG) in the leading order of the ε = 4 − d expansion (one-loop approxima-tion). For n = 2 and 3 the model is equivalent to the scalar and the O(3)-symmetric vector models; for n ≥ 4 it involves two independent interaction terms and two coupling constants.

The significant progress in the present research has been achieved. It is shown that for n > 4 the RG equations have no infrared (IR) attractive fixed points and their solutions (RG flows) leave the stability region of the model. This means that fluctuations of the order parameter change the nature of the phase transition from the second-order type (suggested by the mean-field theory) to the first-order one. For n = 4, the IR attractive fixed point exists and the IR behavior is non-universal: if the coupling constants belong to the basin of attraction for the IR point, the phase transition is of the second order and the IR critical scaling regime is real-ized. The corresponding critical exponents ν and η are presented in the order ε and ε2, respectively. Otherwise the RG flows pass outside the stability region and the first-order transition takes place.

References1. Vasil’ev A.N. The Field Theoretic Renormalization Group in Critical Behavior Theory and Stochastic Dynamics (Boca Raton, FL: Chapman and Hall), 2004.2. Landau L.D., Lifshitz E.M. Statistical Mechanics, 3rd edn, 1976

95

Calculations of excitation and pair-creation probabilities in low-energy U92+ − U91+(1s) collisions in the monopole

approximation

Maltsev [email protected]


Low-energy collisions of heavy ions can provide a opportunity to test quantum electrodynamics effects in the supercritical Coulomb fields [1]. In order to inves-tigate such effects, one needs the theoretical description of various processes in heavy-ion collisions.

In our previous work [2] we developed the method for relativistic calculations of electron excitation probabilities in collisions of a bare nucleus with a H-like ion in a one-electron model. In the present work this approach has been generalized for the many-electron picture, in which the negative-energy Dirac continuum is considered to be fully occupied by electrons. The probabilities of corresponding processes are calculated using the many-body technique [1, 3]. All the initial one-electron states are propagated. The time-dependent Dirac equation is treated within the monopole approximation utilizing the finite basis set of cubic Hermite splines. The monopole approximation allows reducing the two-center Dirac equation to the one-center radial one.

The developed method has been applied for the calculation of pair-creation and excitation probabilities in U92+-U91+(1s) collisions at the projectile energy E=6 MeV/u. The obtained results are compared with corresponding one-electron values. We expect that this work and its further continuation will be required for the future experiments at GSI and FAIR (Darmstadt, Germany).

References1. Greiner W., Mueller B., Rafelski J. // Quantum Electrodynamics of Strong Fields. Springer-Verlag, Berlin, 1985. 2. Deineka G.B, Maltsev I.A., Tupitsyn I.I., Shabaev V.M., Plunien G.// Russian Journal of Physical Chemistry B 6, 224 (2012).3. Fradkin E.S., Gitman D.M., Shvartsman S.M. // Quantum Electrodynamics with Unstable Vacuum, Springer-Verlag, Berlin, 1991.

96

Spectral properties of quasi-periodic Schrodinger equation

Martemyanov [email protected]

Scientific supervisor: Prof. Fedotov A.A., Department of Higher Mathematics and Mathematical Physics, Faculty of Physics, Saint-Petersburg State University

This talk describes results of studies of a small quasi-periodic perturbation of a one-dimensional periodic Schrodinger equation by the method of monodromization [1]. This method was proposed by V. Buslaev and A. Fedotov for studying one-dimensional periodic difference equations on the real axe. Later it was developed by A. Fedotov and F. Klopp [2] and became a method for studying quasi-periodic difference and differential equations.

Following the idea of this method, a study of spectral properties of the original differential operator is reduced to a study of an infinite sequence of difference equations.

In this work we make only the first step and consider the first equation from this sequence in the case, when the perturbation is an analytical function. Then we analyse behavior of its solutions with the help of a construction from KAM-theory. As a result we show that, if the perturbation is rather “small”, the most of the absolutely continuous spectrum of the unperturbed Schrodinger operator remains intact. Moreover, we also suggest a procedure for constructing generalized eigenfunctions of the quasi-periodic operator.

References1. Buslaev V., Fedotov A. // Advances in Theoretical and Mathematical Physics, 5(6):1105-1168, 2001.2. Fedotov A., Klopp F. // Communications in Mathematical Physics, 227:1-92, 2002.

97

Difference in using rapidity and pseudo-rapidity windows for <PT>:Nch correlations in pp collisions with

PYTHIA8 event generator

Neverov [email protected]

Scientific supervisor: Kompaniets M.V., Department of High Energy Physics and Elementary Particles, Faculty of Physics, Saint-Petersburg State University

Correlations between average transverse momentum and multiplicity of charged particles play an important role for studying the so-called collective effects that take place in hadron collisions at high energies, because without taking such effects into account one cannot describe the increase of <PT> with Nch.

The main goal of present work was to find differences in using rapidity and pseudo-rapidity windows in which particles are considered, because former is a kinematical parameter used instead of P|| and is convenient for theoretical calcu-lations, while latter is a similar but not equal parameter which is much easier to measure on experiment.

The work was carried by computer modeling with the Monte-Carlo event generator PYTHIA 8, which is by far the most popular general-purpose event generator for LHC physics.

It was shown that changing rapidity window to pseudo-rapidity one results in translation of <PT>:Nch curve to a higher PT, and thus one has to pay attention to which rapidity is used, e.g. when comparing theoretical predictions to experimental data.

Additionally it was demonstrated that PYTHIA8 provides a good descrip-tion of present data. And a dominant role of peripheral collisions at low Nch was discovered.

References1. http://home.thep.lu.se/~torbjorn/Pythia.html2. Buckley A., Butterworth J., Gieseke S., Grellscheid D., Hoche S., Hoeth H., Krauss F., Lonnblad L., Nurse E., Richardson P., Schumann S., Seymour M.H., Sjostrand T., Skands P., Webber B. // Phys. Rept., 504 (5), 145 – 233; arXiv:1101.2599 [hep-ph], (2011).3. Armesto N., Derkach D., Feofilov G.A. // Nuc. Phys., 71 no. 12, p. 1-10, (2008).4. ALICE Collaboration. // Phys. Lett., B693 issue 2, p 53-68, (2010).

98

Change of a chemical composition of an herb of Achillea millefolium under the influence of an anthropogenic

factor

Oleneva Yu.G. [email protected]

Scientific supervisor: Dr. Pakhomov P.M., Faculty of Physical Chemistry, Tver State University

Under the influence of an anthropogenic factor of a plant are capable to ac-cumulate substances pollutants of the various natures and to change the chemical composition. Therefore by production of medical preparations out of herbs an important stage is the analysis of their chemical composition. The most available and convenient methods for this purpose are methods of optical spectroscopy (IR seen and UV ranges) by means of which it is possible to carry out the qualitative and quantitative spectral analysis of a sample.

As objects of research were used the stalks, leaves and flowers of a yarrow of the ordinary (Achillea millefolium), collected in places with various anthropogenic loading (around combined heat and power plant) and widely adopted, in traditional and traditional medicine. Record IK of ranges of samples in the form of tablets with bromide of potassium (KBr) carried out on Fourier-IK a spectrometer of "Equinox 55" of Bruker firm. For UF of the spectral analysis (Thermo Scientific Evolution Array UV-VIS Spectrophotometer) prepared alcoholic solutions of studied samples. The total content of phenolic connections determined by Folin's method – Chokalteu [1]. With the help of qualitive reaction were defined availability of bioactive agents. In parallel was carried out the quantitative analysis of the content of antioxidants in the extracts of a yarrow collected in various places by means of a method, based on interaction of antioxidants with the free radical a 2,2-diphenyl-1-pikrilgidrazilom.

As a result of the conducted researches it is established that the main changes in IK ranges of studied samples happen at the expense of accumulation of pollut-ing substances and oxidizing processes in various parts of a plant (especially in flowers and stalks) [2]. Is offered the mechanism of the oxidizing processes chang-ing the content of bioactive agents in a plant. In UF ranges of extracts of a plant subjected to pollution, shift of a maximum of a strip of absorption is revealed at 330 nanometers, caused by polyphenol connections, is revealed at towards smaller lengths of waves and emergence new an absorption strip at 270 nanometers. It is suggested that reduction of the maintenance of bioantioxidants in a plant under the influence of polluting substances reduces its medical effect.

References1. Harborn Dzh. Biochemistry of phenolic connections, p. 452, (1968).2. Ilyashenko N.V., Ivanova A.I., Oleneva Yu.G., Khizhnyak S.D., Pakhomov P.M. New steps in physical chemistry, chemical physics, and biochemical physics. -Nova Science Publishers, p. 121-129, (2013).

99

Calculation of self-energy diagrams in the φ4 theory with help of recurrence relations

Artem [email protected]

Scientific supervisor: Prof. Dr. Pis’mak Yu M., Faculty of Physics, Saint-Petersburg State University

The self-energy operator of the φ4 theory is presented as an infinite sum of 1-particle irreducible diagrams. There are two such diagrams for the massless φ4 theory in the 4-loop approximation:

The logarithmic dimension for the φ4 theory is d=4. In this dimension all the diagrams of the self-energy operator are diverged. Therefore we make all the cal-culations in the dimension d=4–2ε and then apply the R-operation.

We introduce two auxiliary graphs:

If a line index is not specified, it is equal to 1.The diagrams Σ1 and Σ2 in the dimension d=4–2ε are expressed in terms of

γ1(ε) and γ2(ε), respectively.We received two recurrence relations: one connects γ1(α) with γ1(α–1) and

another does γ2(α) with γ2(α–1) with arbitrary α. Then we used the fact that these diagrams are finite at α=1 in the dimension d=4. Therefore, these diagrams with index α=1+ε in the dimension d=4–2ε are finite for sufficiently small ε. It enables one to found singular and final parts in ε of the diagrams Σ1 and Σ2 in the dimension d=4–2ε applying the recurrence relation for γ1(α) and γ2(α).

After the application of the R-operation we obtained the following result:

Σ1

2 343333 2064 432 32 352 3

192= −

+ + + + ( )τ τ τ ζ�,g

Σ2

2 34783 444 96 8 56 3

24= −

+ + + − ( )τ τ τ ζg .

Here τ π γ= −ln 4 E , g =λπ16 2 and λ is the coupling constant of φ4 interaction.

100

Computersimulation of Self-Association Processes In Gemini and Monomeric Surfactant Solutions

Raev [email protected]

Scientific supervisor: Dr. Popova M.V., Saint-Petersburg State University, Faculty of Physics, Department of Quantum Magnetic Phenomena

Conventional surfactants hold wide applications in everyday life as well as in industrial processes. Over the last few decades, a new class of surfactant known as Gemini (dimeric) surfactants has received keen attention due to their superior physicochemical properties over the conventional surfactants. They are amphiphilic molecules possessing, in sequence, a long hydrocarbon chain, a polar head group, a flexible (or rigid) spacer, a second polar group and another hydrocarbon tail. Polar groups can be ionic or not. An example of such surfactant is 16-4-16 -tetramethylene-1,4-bis(hexadecyldimethylammoniumbromide).

[C16H33(CH3)2N+(CH2)4N

+(CH3)2C16H33]2Br-

To study these surfactants chosen method of computer modeling, as it provides information on how it is formed from monomers of the micelle.

The main stages of modeling:Creation of individual molecules and the calculation of the charge on each atom

using density functional theory;Creating cells with a solution at room temperature and atmospheric pressure;Study the change in the system over time using molecular dynamics.To create the individual molecules used the program Avogadro 1.0.3. For further

calculations package was used Accelrys Materials Studio. Computer measurements were also performed with a conventional surfactant (cetyltrimethylammoniumbro-mide, CTAB) for comparison purposes. Simulation of systems using molecular dynamics was carried out by the module Forcite. In the simulation used the force field COMPASS. The system had equilibrated for 9ps for 16-4-16 and 50ps for CTAB. Altogether NPT ensemble simulation lasted for 800ps di-CTAB and 550ps for CTAB in increments 1fs.

Obtained radial distribution functions of the atoms of the molecules, the coor-dination numbers and interatomic distances are in good agreement with the data of computer simulations presented in the scientific literature. Establishedthat the process of micelle formation for 16-4-16 and CTAB occurs in several stages.It has been found that in mixtures of monomeric and dimeric compounds for polymor-phism characteristic of self-assembly, even in the initial stage of the self-association process. It was shown that simulation results can be used for dynamic and kinetic characteristics of the model solutions of dimeric and monomeric surfactants. Comparison of the results for CTAB to results from another study showed a good agreement, which increases the accuracy of the data.

101

Dual kinetic balance method in finite-basis-set expansions for axially symmetric Dirac equation

Rozenbaum [email protected]


The solution of the time-dependent Dirac equation is necessary to study the interaction of highly charged ions with laser fields. The use of a finite basis set to solve the Dirac equation leads generally to the appearance of so-called spuri-ous states. It is rather difficult to separate the physical and the spurious solutions. Besides that, the latter ones can make the convergence of the numerical calcula-tions worse.

The Dual Kinetic Balance (DKB) technique allows one to get rid of the spuri-ous states occurring in finite basis set schemes for the Dirac equation. The DKB method was developed for the radial Dirac equation in [1]. In the present work this method is generalized to be employed in the case of the three-dimensional systems with the axial symmetry. In particular, we can apply this approach to the problems of the interaction between heavy ions and strong laser field, including the calculations of the probabilities of the electron-positron pair production.

The transformation of the basis set is the central part of the DKB method. Let B rk k

Nr( ){ } =1 and Ql l

N( )θ θ{ } =1 be the sets of the one-component basis functions. In

case of four-component two-variable basis set given by W r B r P e ukl

uk l u

( ) ( , ) ( ) ( ) , , , ,θ θ= = …1 4 (1)where eu are the standard four-component basis orts, we get the spurious solutions. The DKB-transformed basis set can be represented as follows:

( ) ( ) ( ) ( )2

†2

†12, ,

12

j

j

mu

kl k l u

m

DmcW r B r P e

Dmc

θ = θ

u k N l Nr= … = … = …1 4 1 1, , ; , , ; , , .θ (2)The differential operator Dmj is obtained by excluding the azimuth angle φ from the Dirac equation in the spherical coordinates for particular projection mj of the total angular momentum j.

The calculations of the spectra of H-like ions in external fields confirm that the spurious states do not appear, provided the basis (2) is employed.

References1. Shabaev V.M., Tupitsyn I.I., Yerokhin V.A., Plunien G., Soff G. // Phys. Rev. Lett. 93, 130405 (2004).

102

Canonical formalism for embedding theory with partial gauge fixing

Semenova [email protected]

Scientific supervisor: Dr. Paston S.A., Department of High Energy and Elementary Particle Physics, Faculty of Physics, Saint-Petersburg State University

Research is focused on the problems related with description of gravitation. The formulation of the gravity theory first suggested by Regge and Teitelboim where the space-time is a four-dimensional surface in a flat ten-dimensional space is considered. Canonical formalism for embedding theory with partial gauge fix-ing that match time of the surface and time of the space is developed. The results obtained will be used for developing the canonical formalism for formulation of gravity as a field theory in the ambient space. In the future it may help to avoid some of the problems arising in attempts to quantize the gravity.

References1. Regge T., Twitelboim C. // In proceedings of the first Marcel Grossmann Meeting, Trieste, Italy, 1975. Ed. R.Ruffini, North Holland, Amsterdam, p.77, (1977). 2. Paston S., Semenova A.// International Journal of Theoretical Physics, v. 49, № 11, p. 2648-2658, (2010).

103

Exterior complex scaling method in TDDFT: HHG of Ar atoms in strong laser fields

Sosnova [email protected]

Scientific supervisor: Prof. Telnov D.A., Department of Quantum Mechanics, Faculty of Physics, Saint-Petersburg State University

The exterior complex scaling (ECS) method [1] is applied in the framework of time-dependent density-functional theory (TDDFT) to study high-order-harmonic generation (HHG) of multielectron atoms in intense laser fields [2]. ECS allows one to impose correct (outgoing-wave) boundary conditions on the wave functions at large distances. In our implementation, ECS is combined with the time-dependent generalized pseudospectral method for accurate and efficient solution of the time-dependent Kohn-Sham equations. We make use of LB94 exchange-correlation potential which proved accurate in calculations of unperturbed electronic structure of Ar. Calculations of HHG are performed for the laser pulses with the wavelength of 800 nm and several peak intensities. The HHG spectrum exhibits an intensity-independent minimum corresponding to the photon energy of about 51 eV which is closely related to the Cooper minimum observed in the photoionization cross section of Ar. We found that HHG spectra calculated with the frozen-core potential (that is, not including dynamic response of the electron density) differ significantly from those obtained by TDDFT.

References1. Simon B. // Phys. Lett. A 71, 211 (1979).2. Telnov D.A., Sosnova K.E., Rozenbaum E., Chu S.I. // Phys. Rev. A 87, 053406 (2013).

104

Investigation of stability of solutions of 5-dimensional cosmological model

Tuzov [email protected]

Scientific supervisor: Dr. Golovnev A.V., Department of High Energy and Elementary Particles Physics, Faculty of Physics, Saint-Petersburg State University

We describe the time evolution of solutions of 5D equations of Friedmann-Robertson-Walker type [1]. In this model, by analogy with the standard 4D Friedman model, the equations of state (EoS) are taken in the form: p = wρ ; pS = νρ , (1)where p is the pressure, pS – the pressure in the extra dimension, ρ – the density of matter.

Model parameters w and ν vary within the following intervals: -1≤w≤+1 ; -1≤ν≤+1 (2)

It is shown that the study of the system of four equations supplemented by (1) is reduced to solving two nonlinear differential equations. If parameters of the model are related to each other by a simple condition

then the scale factor of the extra dimension admits a constant solution: b(t) = const. The numerical solution has shown that this model has two regimes for the extra dimension – inflation and dynamical compactification. There is no structural stability.

We discuss the possibility to obtain numerical solutions of 5D cosmological models with more complicated equations of state.

References1. Chad A. Middleton and Ethan Stanley // Phys. Rev. D, 84, 085013.

105

E-teaching and remotely attended seminars: a live demonstration

Ulmer [email protected]

Scientic supervisors: Dr. Philipp Hӧvel, Prof. Dr. Eckehard Schӧll, PhD, Institute of Theoretical Physics, Technische Universitӓt Berlin, Germany

Multimedia and e-learning are valuable tools to enhance education of students. In a three-year project at the Technische Universitӓt Berlin, e-teaching modules for visualization, e.g. of physical theories, were developed to improve teaching both during the lectures and in subsequent phases of self-study. These e-teaching tools, which are freely available, facilitate a better understanding of the curriculum of theoretical physics and received positive feedback from the student body at Technische Universitӓt Berlin as well as teaching staff at other institutions.

By internet-based techniques, students from different locations around the globe can benefit from remote lecture series and research seminars. Courses can be jointly held although the attendees might still reside at their home institutions. The discussion and knowledge transfer takes place by their virtual presence via modern communication tools. This also yields a great benefit for advanced students, who are entering the international conference community. In addition, lectures are given using electronic chalk, which means that they are available on the web as a script for download or replay immediately after the lecture is finished.

In the winter semester 2013/14, a remote seminar on cutting-edge topics in the field of network science and control will be jointly held with the group of Prof. Fradkov (St. Petersburg State University). Using a bi-directional video and audio transmission, this weekly seminar will fundamentally facilitate discussions and promote scientific exchange.

In a live demonstration, we will give a first-hand impression of the potential and possibilities of the modern set-up. Out of the large number of existing visual-izations, a selection of e-modules used in the main courses mechanics, quantum mechanics, electrodynamics, and thermodynamics will be remotely demonstrated. These e-modules and corresponding documentations are available online: http://www.itp.tu-berlin.de/menue/lehre/owl/parameter/en. Furthermore, we will provide an overview how these modern techniques are implemented in the courses of theoretical physics at Technische Universitӓt Berlin.

This project is supported by the German-Russian Interdisciplinary Science Center (G-RISC).

H. Biophysics

108

Conformation and molecular characteristics of poly-2-acrylamido-2-methyl-propane tsetilammoniya in

solution

Akhmadeeva Liliya, Podsevalnikova Anna, Lebedeva Elena, Mikhailova Mariya

[email protected]

Scientific supervisor: Prof. Dr. Tsvetkov N.V., Department of Polymers Physics, Faculty of Physics, Saint-Petersburg State University

Properties and structure of the synthesized polymer depend on many factors, one of which is the organization of the monomers before the beginning of the polymerization reaction. One possible way of obtaining polymers is their syn-thesis in micelles, which consist of ionic surfactants containing groups capable of entering into a polymerization reaction. During the synthesis structure of the product depends on the position due to the polymerizable link in monomer and the monomer concentration in solution at the beginning of synthesis. At present time, the properties of polymers synthesized from organized monomers, actively studied. Investigated based coating such polymers with a low value of surface energy are used to create sensors as gellants.

In this work series of samples of comb-like polymer with ion -linked side chains (poly -2- acrylamido -2- methyl- propanesulfonate tsetilammoniya (CA - PUMPS)) was investigated. The polymer was obtained at different concentrations of monomer in the synthesis process. The samples are studied in chloroform (CF) solutions by the methods of flow birefringence, dynamic light scattering and viscometry.

The difference in the molecular weights of the investigation samples have al-lowed us to obtain the Mark - Houwink –Kuhn equations for the polymer-solvent system. Conformational characteristics of macromolecules CA – PUMPS were defined: the length of the Kuhn segment A = 45 nm, and the effective hydrodynamic diameter d = 1.8 nm. Anisotropy of optical polarizability of the monomer unit was calculated. Influence of the length of the side chain on optical and conformational properties of the studied polymer was detected and discussed in details.

109

Study of DNA interaction with the metallized diphtalocyanines

Alekseev [email protected]

Scientific supervisor: Prof. Dr. Kasyanenko N.A., Department of Molecular Biophysics, Faculty of Physics, Saint-Petersburg State University

Metallized phthalocyanines have a wide application in various fields of tech-nology. They can be used, for example, in antitumor treatment as photosensitizers for photodynamic therapy. High molecular calf thymus DNA (Sigma) was used in our experiments. Diphthalocyanines under investigation have spherical shape and contain nickel, cobalt and copper as coordinating centers. They were synthesized in the laboratory of Prof. A. Sengul (University Karaelmas Zonguldak, Turkey).

The influence of metallocomplexes on DNA conformation in a solution was studied by spectroscopy (SF-56, Russia), circular dichroism (Mark IV, France), and low-gradient viscometry. The process of complex formation was studied at different concentrations of components and ionic strengthes of the solution. The process of preparation of systems and its influence on the result of investigation was also analyzed. The comparison of DNA complexation with three metal com-plexes can provide the understanding about role of ligands and central metal atoms in interaction. It was shown that the results of binding to DNA are similar for the compounds with different metals. They cause same changes in DNA conforma-tion, However, the optical properties of the compounds show that the binding is accompanied with the variety in the state of the compounds.

Is was shown that compounds interacts with DNA phosphates. The interac-tion can be registered immediately after the preparation of the systems and does not change in time. Coordination bonds between metal atoms and DNA do not formed. Viscometry method showed that the volume of DNA molecule reduces in the presence of phthalocyanines. The presence of DNA in solution stabilizes the solvent of phthalocyanines. DNA prevents the precipitation of phthalocyanines from the solution.

110

Models of DNA Interaction With Ruthenium Compounds Containing Biological Active Ligands

Kozhenkov [email protected]


Drugs, basing on coordination compounds of metals of the platinum group, occupy a special place among anticancer drugs. This paper presents the results of a study of influence of two potential anticancer compounds, basing on ruthenium (II) [Ru(η6-cymene)Cl(O,O-nalidixicato)] and [Ru(η6-cymene)Cl(phen-Ph2)]Cl, on conformation of DNA molecules in solution. The practical importance of the work is due to the fact that the data obtained in this work contribute to a directional change in the chemical structure of known compounds and to provide information on the future direction of synthesis for the development of new anticancer drugs in this class. Indeed, the effect of drugs, aiming at the destruction of malignant tumors, is basing on the formation of irreversible complexes with nuclear DNA. Therefore, model systems (aqueous DNA solution) may be used to establish the nature of the molecular mechanism of action of the novel compounds synthesized by the treatment of such pathologies. Comparison of the results with the action of the most active but also very toxic drugs of this class (cisplatin) will help to identify features of the influence of structural characteristics on the result of interaction.

In this paper the interaction of compounds Ru(η6-cymene)Cl(O,O-nalidixicato)] and [Ru(η6-cymene)Cl(phen-Ph2)]Cl with molecule of DNA in solutions of vary-ing ionic strength and pH has been studied using lowgradient viscometry, UV-spectroscopy, circular dichroism, electrophoresis and atomic force microscopy. Also quantum-mechanical calculation of the structures of the compounds was carried out. After that these structures were used in molecular docking procedure on DNA. Thus, the simultaneous use of the experimental methods and the theoretical calculations allow more fully describe the model of interaction of the compounds with DNA. It is shown that compounds Ru(η6-cymene)Cl(O,O-nalidixicato)] and [Ru(η6-cymene)Cl(phen-Ph2)]Cl interact with the DNA molecule, causing a change in its conformation. Complex formation is realized in low ionic strength solutions, while under physiological conditions (0.15 M NaCl) and higher concentrations of salts in solution, binding becomes more difficult. This is typical for such compounds. Also in this paper present analysis of the data and propose a model of the interac-tion of compounds with DNA. Some important experimental values were prepared and evaluated: the binding constant for Ru(η6-cymene)Cl(O,O-nalidixicato)] and pK values for the two compounds at different ionic strengths.

111

UVC-induced DNA destructions in vitro

Parr [email protected]

Scientific supervisor: Dr. Paston S.V., Department of Molecular Biophysics, Faculty of Physics, Saint-Petersburg State University

It is known that as a result of UV-light influence on DNA some chemical modi-fications in it appear (the main type of modifications is nitrogenous bases dimeriza-tion) which cause the destruction in the secondary structure of DNA molecule [1]. At the present work we studied the role of the ionic strength of the solution in the UVC-induced changes in the DNA spectral properties. As a source of UV-light the low preasure mercury lamp was used (8 Wt, λmax=254 nm).

In the DNA absorbtion spectra we found monotonous increasing of intensity at the short-wave range (near 230 nm) and out of the DNA absorbtion region (at 310 nm) with the growth of UVC doze. The intensity at the maximum of DNA spectrum (at 260 nm) did not change essentially. The decreasing of DNA hyperchromic ef-fect after the UV-irradiation of DNA solutions was found. UV-irradiated and then hydrolyzed DNA (i. e. without any secondary structure) had lower intensity at the maximum, but at the short-wave range the absorbance is almost the same as in the non-irradiated hydrolyzed DNA. Such a behaviour of the spectral properties is similar to the observed for the UVC-irradiated solutions of thymine [1] and oligonucleotide d(pT)16 [2].

The nitrogenous bases concentration (determined by the method described in [3]) decreases with the irradiation dose rise. This effect can be related both with the amount of monomeric bases lowering or with the chromophore loss. The DNA molar extinction coefficient ε260(P) increased with the UVC doze growth, which indicates the DNA partial denaturation. All these effects weakly depend on the ionic strength of the solution under UV-exposure.

The work was supported by Russian Foundation for Basic Research (RFBR, grants 12-08-01134 and 13-03-01192) and the Ministry of Education and Science of Russian Federation.

References1. Smith K., Hanawalt Ph. // Molecular Photobiology. Academic Press, NY, London (1969).2. Mu W., Zhang D., Xu L., Luo Zh., Wang Y. // J. Biochem. Biophys. Methods, v. 63, p. 111 (2005). 3. Spirin A.S. // Biokchimiya (USSR), v. 23, p. 656 (1958).

112

Dielectric properties of liquid crystal complex on the base of Ytterbium

Sakhatskiy [email protected]

Scientific supervisor: Prof. Kovshik A.P., Department of Polymer Physics, Faculty of Physics, Saint-Petersburg State University

The study of the dielectric properties of liquid crystal coordination compounds of lanthanide is of great interest. Being paramagnetic these liquid crystals have anomalously large anisotropy of magnetic susceptibility. They are distinguished by the ability to easily vary their orientation in external electric and magnetic fields.

The object of the study is a complex of liquid crystal with the Ytterbium as a complexing element. This compound possesses a nematic phase for which the transition temperature to the isotropic phase is equal to 130 °C.

The investigations were performed using an impedance meter HIOKI LCR HiTESTER 3532 within the frequency range 45 Hz – 5 MHz and in the tempera-ture range 90 – 130 °C.

In this liquid crystal the permittivity along and transverse to the axis of preferred orientation, ε║ and ε┴, were measured. The observed dispersion of the permittivity was described by Cole-Cole equation, taking into account the conductivity:

ε εε ε

π τ∞∞

α*

Ni fi Bf

= +−

++−

011 2( )

.

Values ε0, ε∞, τ, α, B, N were chosen in such a way that the theoretical curve passes through the experimental points . From the dependence of the relaxation time τ on the inverse temperature the activation energy of the dielectric relaxation was determined from the Arrhenius equation

τ τ= 0exp UKT

( ) .

113

DNA Interaction with divalent cations in the presence of EDTA

Ushkov Pavel, Paston [email protected]


Plural-component systems contained DNA, ligand and cations Меn+ are very perspective objects for fundamental and applied investigations for the needs of molecular biology, pharmacy, bioengineering, etc. [1, 2]. In our work by the methods of UV-spectroscopy and circular dichroism the water-solt DNA solutions with cations Mg2+, Mn2+ and Cu2+ and also with the chelating agent – EDTA – were studied.

We conclude that EDTA does not affect the DNA secondary structure in 0.005 M NaCl solution up to the concentration of 1•10-2 М. Mn2+ and Cu2+ form complexes with EDTA in aqueous solutions starting from the molar ratio 1:1 and also at the plenty of EDTA. These complexes can be observed in UV-absorbance spectra. In MgCl2 solutions (up to the concentration of 1•10-4 М) the cation interaction with nitrogenous bases in DNA was not found both in the presence or in the absence of EDTA. After the EDTA addition to the DNA-Mn2+ and DNA-Cu2+ complexes we found their partial dissociation at some ratio of the components. Our experimental results show that cations influence on the DNA spectral properties and secondary structure in the presence and in the absence of EDTA is in the following order: Na+ < Mg2+ < Mn2+ < Cu2+. This order correlates with the stability constants of cations-EDTA complexes: (lgK1Na+=1,7; lgK1Mg2+=8,7; lgK1Mn2+=13,6; lgK1Cu2+=18,8) [3].

Part of the work was supported by Russian Foundation for Basic Research (RFBR, grants 12-08-01134 and 13-03-01192) and the Ministry of Education and Science of Russian Federation.

ReferencesSzczepanik W., Kaczmarek P., Jezowska-Bojczuk M. // Journal of Inorganic 1.

Biochemistry, v. 98, p. 2141 (2004).Ji S., Chen M., Li H., Gan G., Li W. // Spectochimica Acta, part A, v. 88, p. 2.

124 (2012).Perrin D. // Organic complexing reagents: structure, behavior, and application 3.

to inorganic analysis. Interscience Publishers (1964).

114

DNA-Metallic Nanoparticles Systems

Varshavskiy [email protected]


Metallic nanoparticles (NPs) are at the objects of intense study due to the rapidly developing of new approaches including nanomaterials. Their unique size-dependent properties make these materials attractive in many areas of high technologies. For example, sensors for applications in medicine and biology, optoelectronic nanodevices in which nanometer size of the individual elements are related to optical frequencies they operate, and other nanoparticles are used for fabrication of pharmaceutical drugs. Biosensors based on surface plasmon are applied for biochemical tests for glucose and urea, for immunoassay of proteins, hormones, drugs, steroids, and viruses, DNA analysis, and finally, to study the kinetics of the drug in real time.

Silver NPs were synthesized by our collaborators in National Technical University of Ukraine “Kyiv Polytechnic Institute” with the use of a new electric-spark dispersion technique and silver NPs, which we synthesized independently. For the experiments we used calf thymus DNA (Sigma) with a molecular mass 8x106 Da, determined from the value of DNA intrinsic viscosity in 0.15 M NaCl solution and polyallylamine 25 000 Da, sodium borohydride and silver nitrate.

In the course of this work it was shown that silver nanoparticles are stable in aqueous solution for several months, the presence of DNA influences the silver nanoparticles and stabilize their solutions. The optimal ratio for silver nitrate and sodium borohydride in aqueous solution was determined. On this conditions the formed nanoparticles are stable for several months and have an average size of about 12 nanometers. Silver nanoparticles are not fixed on a mica surface.

I. Resonance Phenomena

in Condenced Matter

116

Behavior of Sodium Lauroyl Sarsosinate with Added Cosurfactants in Aqueous Solution

Bubnov [email protected]


1. Interest in the study of Binary MixturesAs well known, commercially used surfactants are invariably mixtures of two

or more types of surfactants. The understanding of the nature of macromolecular aggregates is consequently of great technological relevance. Although such systems have been used for a long time, knowledge of the detailed structure and size of different kinds of mixed surfactant molecules in the co-aggregates still requires further study. Besides, many problems on the conformational changes of molecules still remain unresolved. As well as despite a large number of studies of micellar systems direct microscopic investigations of surfactant dynamic and aggregate structure as their aggregation state changes from micellar to monomeric and back to micellar are still quite rare.

2. ResultsWe have performed NMR studies including 13C and 1H chemical shift and 1H

relaxation time measurements of aqueous solutions of SLAS and binary mixing systems (SLAS - D2O - co-surfactant) at different surfactant concentration and/or temperature. As co-surfactant we used anionic amphiphiles with different hydrophobic chains: potassium hexanoate, potassium octanoate and potassium decanoate.

In the 13C and 1H spectra of SLAS every resolved carbon or proton nucleus causes two signals due to the existence of two conformers (trans- and cis-) of sur-factant molecules in solutions and binary mixtures. The population values of both conformers depend on the surfactant concentration and temperature. For example, the population of the trans-conformers relative to that of the cis-conformers was found to increase with increasing concentration. This observation indicates the trans-conformer of SLAS is more stable in the micelle state than in the monomeric state. The separation of the trans- and cis- resonance lines, which called internal chemical shift, is influenced by the concentration of SLAS and/or co-surfactant as well as by the temperature.

117

Analisys of translational diffusion in binary system glycerol-heavy water by NMR

Bystrov [email protected]

Scientific supervisor: Chernyshev Y.S., Department of Quantum Magnetic Phenomena, Faculty of Physics, Saint-Petersburg State University

Surfactants are compounds that lower the surface tension and that are am-phiphilic, meaning they contain both hydrophobic groups (their tails) and hydro-philic groups (their heads). The insoluble hydrophobic group may extend out of the bulk water phase. In the bulk aqueous phase, surfactants form aggregates, such as micelles, where the hydrophobic tails form the core of the aggregate and the hydrophilic heads are in contact with the surrounding liquid.

This research is a part of a program devoted to the study of the effects of glycerol on the micellization of surfactants (in our case of ionic liquids) in aqueous solution that are of great interest for cosmetology, pharmaceuticals and other industries.

Unfortunately, while studying the NMR spectra of these solutions it can be found that the lines of glycerol and from, for example, ionic liquid strongly overlap, that complicates the further structural analysis of the system.

In this regard, there was a necessity to consider the auxiliary problem: experi-mentally evaluate the effect of glycerol on the diffusion of individual components in a solution by measuring the self-diffusion coefficients of the nuclei 1H and 2H in the system glycerol - heavy water.

The significant progress in the preliminary research has been achieved and the results are summarized in the present work. Because of some discrepancies between different data sets present in the literature, we made a comparative analysis of the data from the University of Napoli.

References1. Diffusion Coefficients for the Binary System Glycerol + Water at 25. A Velocity Correlation Study. -Via Cinthia, 80126 Napoli, Italy.

118

Investigation of the 1,5 T magnetic field inhomogeneity with dimensional projections of the phantoms

Dmitriev [email protected]


The main characteristic of a magnetic resonance imager is a transfer accuracy of the spatial coordinates, which primarily depends on the homogeneity of the main magnetic field imager. Inhomogeneity occurs due to the large number of different factors, ranging from imperfections of the magnet to the presence of patient inside the MRI apparatus.

The aim of this work was to determine the shape and size of the inhomogeneity of magnetic field for the specific installation.

In order to achieve this, the following tasks were resolved: a) calibration phantoms were designed and manufactured for validation of the initial conditions; b) the dependence of the resonance frequency change from heating of the magnet was investigated; c) the working sample with a small amount of glycerin (V = 0,0204 ml) was made for obtaining a "point effect"; d) resonance frequency in a plane parallel to the gap of the magnet along the perpendicular axes (X, Y) was measured; e) the inhomogeneity value of the axes (X, Y) was calculated.

In addition to this, the dependences of inhomogeneity from the coordinates were obtained.

Based on the these data, it can be concluded that in order to achieve the best results on this setting the sensor should be placed with the sample in the gap of the magnet at the point with coordinates (X, Y) = (30, 50). Furthermore, since the gap of the magnet has a circular shape, it can be assumed that the inhomogeneity will have the axial symmetry.

119

Hydrogen site occupancy in the Ti1-xNbxHy hydrides by proton NMR

Ievleva [email protected]


Efficient and safe storage of hydrogen is one of the most important problems for the extensive use of hydrogen as an energy carrier. Among metal hydrogen systems MgH2 is one of the most promising hydrogen storage materials; however the rather high hydrogen sorption temperature and slow hydrogen sorption kinet-ics limit its applications. Nevertheless, addition of transition metals, like Ti, V, Nb or their alloys essentially improve these properties. Moreover, Ti-V or Ti-Nb based alloys can be used as hydrogen storage materials themselves (despite their hydrogen storage capacity is not very high, the hydrogen sorption temperature can be varied within the required area). From this perspective deeper knowledge on local structure and hydrogen mobility are helpfully required.

Appreciable enlightening of main characteristics (static and dynamics) can be provided using the nuclear magnetic resonance (NMR) method which is an especially powerful tool to investigate metal hydrogen systems. Here we report on the results of our 1H NMR study of Ti1-xNbxHy hydrides (x = 0.3, 0.5, 0.6 and y ≈ 2) prepared using the self-propagating high-temperature synthesis method [1]. One of the questions of interest is where the hydrogen atoms are localized? To give an answer we have recorded the 1H NMR line at different temperatures and analyzed the line shape using the Van Vleck method. All experiments were made using the home-built cw NMR spectrometer at proton frequency equal to 43 MHz. The line shapes were analyzed using the MagicPlot package [2]. The second moment calculations were carried out taking into account 1H-1H and 1H-93-

Nb contributions, supposing random distributions of both metallic and hydrogen atoms over their sites.

It was found that in studied hydrides with fcc structure hydrogen atoms are distributed between both tetrahedral (T) and octahedral (O) sites: the O-sites are almost half occupied, whereas the occupancy of T-sites is about 75%.

The work was supported by Saint Petersburg State University (Project 11.0.63.2010: Pulse spectroscopy of anisotropic and nanostructured materials).

References1. Aleksanyan A.G. et al. // J. Alloys Compds. 509 (2011) S786-S789.2. http://magicplot.com

120

Comparative experimental and theoretical NEXAFS-study of Acenes and Azaacenes

Michael [email protected]

Scientific supervisors: Klaus Hermann, Theory Department, Fritz Haber Institute, Berlin; Prof. Dr. Gregor Witte, Physics Department, Physilipps Uni. Marburg

NEXAFS is a powerful tool to investigate the electronic Structure of molecules. The full information of these spectra is only accessible with a precise assignment of resonances to excitations. Therefor a theoretical analysis of spectra is needed, which is problematic due to the need of calculating core-excitations. StoBe [1] is a quantum mechanical ab initio DFT-code which is designed to handle this task. Here we use this program to calculate theoretical NEXAFS-spectra of small Acenes, Azaacenes and there hydrogenated relatives and compare these results with our experimental data. By comparing spectra of Acenes and Azaacenes, we carve out the influence of the higher core charge of Nitrogen on the electronic structure. While this effect on the one hand is quite small, we study the influence of hydrogenation on the other hand. Even though adding two Hydrogens is in a sense the smallest chemical modification one can think of, it has great effect on the electronic structure because the conjugation of the pi-system is broken. This leads to a strongly modified NEXAFS-signature which is a example for the building-block-theory.

References1. Hermann K., Pettersson L.G.M. et al. StoBe demon version 3.1.2011.

121

Ab initio simulation of hydrogen diffusion paths in magnesium dihydride

Klyukin [email protected]


Magnesium dihydride has attracted a lot of attention as a reversible hydrogen storage material because Mg is abundant on the Earth, inexpensive, and has a high hydrogen capacity of 7.6 mass%. However, any practical applications are limited by the slow kinetics and high temperature of reactions with hydrogen. Nevertheless, it was found that a limited dissociation rate of hydrogen on the metal surface may be improved by additions of transition metals catalyst (TM). But up to now the role of the interface border between Mg and TM remains unclear.

In our previous work [1] we have studied the microstructure of the Mg/Nb interface. It was found that Nb additives stabilize the Mg bcc structure near the interface border. Also we have studied H-induced transition in Mg [2], it was found that hydrogen atoms tend to be randomly distributed over the interstitial sites in the bcc-MgHx structure, despite inserted into MgHx with hcp, fcc and rutile lattice, hydrogen atoms prefer to occupy neighboring interstitial sites, to form a kind of clusters.

Using first-principles calculations we have investigated diffusion behaviors of hydrogen in various (hcp, bcc, fcc) structures of Mg, possible migration pathways were considered. At low hydrogen concentration mechanisms of H atom migration between neighboring internal sites were determined. Then the activation barrier was found as the difference between the optimized transition state and the ground state. For all diffusion energy barriers zero-point correction was estimated. Also the simple estimation of the diffusion coefficient was performed.

Our calculations have shown that hydrogen in bcc Mg structure (e.g. occurs near the Mg/Nb interface) has the highest diffusion rate and the lowest activation barrier.

References1. Klyukin K., Shelyapina M.G., Fruchart D. //Solid State Phenomena 170, p. 298-301 (2011).2. Klyukin K., Shelyapina M.G., Fruchart D. //Journal of Alloys and Compounds, http://dx.doi.org/10.1016/j.jallcom.2013.02.089 (2013).

122

Study of radiation defects in paleontological objects by electron paramagnetic resonance

Kultaeva [email protected]

Scientific supervisor: Dr. Sukharzhevskii S.M., Department of Quantum Magnetic Phenomena, Faculty of Physics, Saint-Petersburg State University

Currently, occurs printing a large number of works devoted to the study of the crystal structure of biological and synthetic apatites. Found that the inorganic phase in the enamel of human teeth is hydroxyapatite. However, the actual structure of the apatite is significantly different from the idealized model: energy diversity of the hydroxyl groups are not equivalent to the different positions of the fluorine atoms, localization of carbonates in the two positions, instead of orthophosphate groups and on the hexagonal axis of the structure.

In the context of this paper will focus on the radical СО2 as it is used in the problems of dating tooth enamel. Irradiation enamel ground leads to an asymmetric composite signal (AS) ESR values near g = 2 . This signal is investigated in the problems of dosimetry, dating, medicine and as a source of information about the structure of apatites.

Electron paramagnetic resonance was obtained more detailed information about places of localization of carbonate material, as well as registered signals from other oxide radicals. Substitutions in the apatite lattice lead to corresponding parameters in the crystal lattice.

In the course of work was obtained results, showing a legitimate orientation of fibers in the structure of the tooth enamel. These results may allow to create a model for dating paleontological biological objects not only on the enamel, but also the bones.

References1. Morgan H., Wilson R.M., Elliott J.C. et al. // Biomaterials.- 2000.- V. 21.- P. 617-627. 2. Grün R., Stringer C.B. // Archaeometry V. 33, № 2. Great Britain, 1991. P. 153-199.

123

A model of behavior of nuclear magnetization in alternating magnetic field of low frequency

Kupriyanov Pavel, Zharinov [email protected]

Scientific supervisor: Prof. Dr. Chizhik V.I., Department of Quantum Magnetic Phenomena, Faculty of Physics, Saint-Petersburg State University

This work is devoted to the investigation of the nuclear magnetic resonance (NMR) in the Earth magnetic field. Some peculiarities of the polarization of nuclei with an additional strong magnetic field have been considered. In particular, the polarization of nuclei with an alternating magnetic field at a very low frequency F (but F >>1/T1, where T1 is the spin-lattice relaxation time) has been investigated. It is convenient and useful to turn the additional magnetic field on the perpendicu-lar direction relatively B0. We have been shown that in this case it is possible to fulfil the conditions of the adiabatic change of the summary field direction. The description of the process can be carried out on the basis of the Bloch equations using the "shaking" frame:

dMdt

M M tT

z=− − 0

1

( )

where M0(t) is the equilibrium nuclear magnetization which is determined the by the summary magnetic field.

The application of the alternating mag-netic field can help to decrease transient pro-cesses in an NMR sensor if the polarization current is switched off at the certain phase. The amplitude of damping transients can be approximately in 50 times less than in the case of switching continuous current off.

The process model of the growth of the mag-netization in low frequency alternating magnetic field is been developed. Two ways to model the behavior of the magnetization is suggested. Both methods lead to the same result. The numerical solutions of equation for the particular cases are shown in Fig. 1. One can see that limiting value of the nuclear magnetization is 0.637 in accordance with the analytical solution for the direct component of the modulus of summary magnetic field.

The experimental results which are confirmed the theoretical predictions.The work is supported by the RFBR grant (13-03-91372 CTa).

0 1 2 3 40

10

20

30

40

50

60

70

80

90

100

0

10

20

30

40

50

60

70

80

90

100

DC

mag

ni tez

ati o

n (%

)

t/T1

c

b a

c

b

a

d

Fig. 1. The time dependence of the nuclear magnetization for different relations of 1/fm and T1 in the case of the alternating polarization field: a) 1; b) 0.3; c) 0.1. For compari-son, the dependence for the perma-nent polarization (for the same am-plitude of the polarization field) is presented (d).

124

Temperature features of hydrophobic and hydrophilic interactions

Rabdano [email protected]

Scientific supervisor: Dr. Donets A.V., Department of Quantum Magnetic Phenomena, Faculty of Physics, Saint-Petersburg State University

Mutual influence of hydrophobic and hydrophilic interactions in aqueous solutions attracts great interest due to their important role in different biological processes such as protein folding or substance transfer in cells. In this work we studied temperature features of these interactions by NMR relaxation and quantum chemical calculations. We have successfully determined temperature changes of the microstructures and mobility of hydrophilically and hydrophobically hydrated water molecules in the organic molecules hydration shells.

Investigated systems are aqueous solutions (D2O) of malonic acid, glycine and β-alanine. The solvent structure in the solutions with organic molecules can be di-vided into several substructures: hydration shells of carboxylic, amino, methylene groups and pure solvent. The total relaxation rate of the solvent nuclei is equal to the sum of contributions of each substructure [1]. Investigation of concentration dependences of the spin-lattice relaxation rates of solvent nuclei in the solutions with different organic molecules allows us to determine the mobility of the water molecules near particular fragments of organic molecule. The temperature depen-dences of NMR relaxation rates help us to understand the temperature variation of the microstructure near hydrophobic and hydrophilic parts of molecules.

The water molecules near the hydrophobic functional groups of organic mol-ecules are characterized by less mobility than in bulk phase. For example, the relaxation rate of the water deuterons near the hydrophobic methylene groups is higher than in bulk water approximately by factor 1.7. This relation shows the decreased mobility of water near hydrophobic fragments and remains at all tem-peratures from 0 to 75 ˚C. On the other hand the mobility of the water deuterons near the hydrophilic carboxylic group is higher than in bulk solvent at temperatures below 30 ˚C, and is almost equal at higher temperatures.

References1. Chizhik V.I. // Molecular physics, v. 90, № 4, p. 653, (1997).

125

Structure of hydrogen bonded complexes formed by strong CH-acids: NMR, IR, X-Ray and QM

investigation of 1,1-dinitroethane

Tupikina [email protected]

Scientific supervisor: Dr. Tolstoy P.M., Department of Molecular Spectroscopy, Faculty of Physics, Saint-Petersburg State University

Hydrogen bonding plays an important role in a nature, particularly in stabiliza-tion of different molecular structure. Whereas the function of standard hydrogen bonds such as NH···O and OH···O is now appreciated, the contributions of weaker interactions (such as CH···X, X – is the proton acceptor atom or atoms group) remain an active area of inquiry. There is a number of interesting examples, which shows the importance of CH···X interaction. For example, formation of a relative weak hydrogen bond between OH-group of ibuprofen and one of carbon atoms of tyrosine most likely is the basis of medical action mechanism of ibuprofen [1]. The next example is stabilization of α-helix by formation CH···O hydrogen bond [2]. Formation of CH···X bond is also a primary step of CH proton transfer – the most ubiquitous reaction is biochemical synthesis [3].

In this work we study relatively strong CH···X hydrogen bonds, formed by 1,1-dinitroethane (pKa = 5.2 [4]) and different proton acceptors in solvents of various polarity. Proton donating ability of 1,1-dinitroethane is sufficiently high to form complexes of various structures, including those with proton transfer, i.e. ion pairs of the C−···HB+ type [5].

For determining structure of complexes we were using different experimental methods – NMR, IR spectroscopy, X-Ray crystallography analysis and quantum mechanical calculation. Also we explore the correlation between NMR parameters and structure of complexes.

References1. Kowalska-Baron J.A., Brychtova M., Petrovic I., Passos Sene I., Quinones P., Sogorkova J. // Biotechnol Food Sci, v. 75, № 2, p. 15, (2011).2. Manikandan K., Ramakumar S. // Proteins., v. 56, № 4, 768, (2004).3. Scheiner S. // Curr. Org. Chem., v. 14, p. 106.4. George W. Gokel. Handbook of organic chemistry. McGraw-Hill, (2004).5. Golubev N.S., Denisov G.S., Ignatiev Y.A. // Org. Magn. Res., v. 7, № 4, p. 185, (1975).

126

Table of ContentA. Chemistry ...................................................................................................... 5

Studying the influence of reducing agent in the process of laser-induced deposition of copper from solutionAraslanova Svetlana, Khairullina Evgeniia, Safonov Sergey ............................. 6

Synthesis, characterization and photophysical properties of luminescent bimetallic Au(I) complexes with 9,10-bis(diphenylphosphino)anthraceneBelyaev Andrey .................................................................................................... 7

Optimization of sample preparation methods nails for digital spectrographic trace element analysisBudalyaeva Rinata .............................................................................................. 8

Solubility and liquid-liquid equilibrium in quaternary reacting system ethanol - ethyl acetate - acetic acid - water at 30 °C and 40 °CGolikova Alexandra, Toikka Maria, Trofimova Maya ......................................... 9

Optimization of the solution to obtain a microthermocouple by the method of LCLDGorshkova Ksenia, Logunov Lev, Safonov S.V. ................................................. 10

Surface enhanced raman scattering of brilliant green on Au -Ag-C nanoparticles Kireev Alexey, Olshin Pavel .............................................................................. 11

Homo- and bridging heterometallic complexes of rhenium with transition metals: synthesis and structure characterizationKisel Kristina .................................................................................................... 12

Microwave synthesis of ultrafine alumina powderMitrofanov Andrey ............................................................................................ 13

Composition influence on the lithium-phosphate glasses structureOlshin Pavel, Kireev Alexey .............................................................................. 14

Optical digital spectrography with arc discharge in microelement analysis of liquid samplesSavinov Sergey .................................................................................................. 15

Switching on luminescence of a platinum(II) complex by conjugation with human serum albuminSolomatina Anastasiya ...................................................................................... 16

127

Digital atomic emission spectrographic determination of trace contaminants in cosmetic shadowsTimofeeva Tatyana, Savinov Sergey .................................................................. 17

Digital atomic emission spectrographic analysis of vineTitova Anna, Savinov Sergey ............................................................................. 18

Adsorption properties of chalcogenide films to protein or DNA for the biochip applicationVasileva Anna .................................................................................................... 19

B.Geo- and Astrophysics ................................................................................ 21

Extension of the i-CRS stacking operator for the 3D Abakumov Ivan .................................................................................................. 22

Time-lapse anomalies reconstruction via joint inversion of direct waves and reflection images: application to crosswell dataAbakumov Ivan .................................................................................................. 23

Multi-wavelength evolution of the solar complex activityKorolkova Olga ................................................................................................. 24

Evolution of isolated OB associations in the Milky WayKorsunov Igor ................................................................................................... 25

Spiral structure and bulge/disc decomposition analisisSavchenko Sergey, Mosenkov Alexsander ......................................................... 26

С. Mathematics and Mechanics ..................................................................... 27

On the solvability of ordinary differential equations with integral conditionsDarovskaya Ksenia ........................................................................................... 28

Stability of CW Solutions of Fourier Domain Mode Locked LaserKashchenko Alexandra ..................................................................................... 29

Design and Control Strategies of Anti-Lock Braking SystemsKoeppen Thomas ............................................................................................... 30

Limit Cycles in EconomicsLi Li ................................................................................................................... 31

128

Scattering of Solitons for Coupled Wave-Particle EquationsMashkin Timur .................................................................................................. 32

Analysis of the oscillatory regimes of the second-order nonlinear delay differential equationMoryakova Alena .............................................................................................. 33

Regularity of solutions to functional differential equationsNeverova Daria ................................................................................................. 34

The research of attractors of quasi-linear Korteweg-de Vries equationPreobrazhenskaia Margarita ............................................................................ 35

Geometric Sparsity and Structured Compressed SensingStojanoska Irena ............................................................................................... 36

On strongly elliptic functional-differential equation with orthotropic contractionsTasevich Alla ..................................................................................................... 37

D. Solid State Physics ...................................................................................... 39

Investigation of electronic properties of the Si – low-melting salt interfacesBekasov Vladimir .............................................................................................. 40

Growth of graphene with boron impurities and its electronic structureBokai Kirill........................................................................................................ 41

Plasmon-LO-phonon Modes in Gallium Nitride Epitaxial Layers Doped with SiliconBorisov Evgenii ................................................................................................. 42

Synthesis of ultrathin magnetic films of transition metals silicides (Fe, Co, Mn) on silicon surfaceGrebenyuk Georgy ............................................................................................ 43

X-ray reflectometry study of Al2O3-based heterostructuresKonyushenko Marina ........................................................................................ 44

Rashba effect in Graphene grown on different substratesMarchenko Dmitry ............................................................................................ 45

Optical and electric properties of GaN crystals grown by HVPEMedvedev Oleg .................................................................................................. 46

129

DFT modeling of the MoS2 nanoparticlesMikheenko Evgenii ............................................................................................ 47

X-ray transitions in single Mg, Mg++ and in MgO crystalMilov Igor ......................................................................................................... 48

Structure and morphology of selenium containing nanosystemsNikolaev Filipp .................................................................................................. 49

Mn2+ intracenter luminescence study in the heterostructures with ultra-thin MnTe layersOzhmegovEgor .................................................................................................. 50

Synthesis and electronic structure of graphene fabricated with the solid-state carbon source on the thin film Ni (111) adsorbed on the single crystal graphite (HOPG)Pudikov Dmitrii ................................................................................................. 51

Dynamical Diffraction of Light in Opal-like Photonic Crystals: 1D Spatially Periodic Structure ApproximationRomanenko Konstantin ..................................................................................... 52

Spin–orbit coupling induced electronic structure of 3 ML Au/W(110) and 3ML Au/Mo(110) surfacesRusinova Mariia ................................................................................................ 53

Combined DLTS/EBIC study of dislocation related electronic states in plastically deformed siliconShlyakhov Ilya ................................................................................................... 54

Determination of misfit stresses, curvatures, defects and termomechanical properties of Si-SiC(111)-AlN(0001)-Al1-xGaxN thin-film heterostructure. Ab initio, FEM and experimental studiesTelyatnik Rodion ............................................................................................... 55

Characterization of pristine and fluorinated nanodiamonds by X-ray absorption spectroscopyZagrebina Elena ................................................................................................ 56

The comparison of different methods of graphene synthesisZashikhin Georgy, Pudikov Dmitrii .................................................................. 57

130

Quantum conductance along dislocation networks produced by silicon wafer bonding Zharinov Vyacheslav ......................................................................................... 58

E. Applied Physics ........................................................................................... 59

Poly(methyl methacrylate) modified by zirconium dioxide nanoparticles Antipov Mikhail ................................................................................................. 60

The research into the conductivity of a loaded piezoelectic transducerBelyaev Vladimir ............................................................................................... 61

Migration of the radionuclides from nuclear accidents in the forest ecosystemMerzlaya Anastasia ........................................................................................... 62

Structuring of photosensitive polymer films by Surface Plasmon near fields Papke Thomas1, Petrov Yuri 2, Mikhailovskii Vladimir2, Vjvenko Oleg2 and Santer Svetlana1 ................................................................................................ 63

F. Optics and Spectroscopy ............................................................................ 65

The effect of the electrolytes on gelation processes in aqueous cysteine–silver nitrate based solutionsAndrianova Yana ............................................................................................... 66

Theoretical Analysis of Mode-Locked Semiconductor Lasers with External Periodic ForcingArkhipov Rostislav ............................................................................................ 67

Transient Cherenkov Radiation from a Periodic Resonant Medium Excited by an Ultrashort Laser Pulse Propagating at Superluminal VelocityArkhipov Rostislav ............................................................................................ 68

Some aspects of the fractional derivatives application in biophysical modelsBatalova Anastasiya .......................................................................................... 69

Computer simulation of nonlinear dynamics of two charged particles on a circleBorovykh Stanislav ............................................................................................ 70

Resonance radiation trapping in free-burning arc inhomogeneous plasmaKalanov Dmitry ................................................................................................. 71

131

Luminescence of Y3Al5O12:Eu3+ nanoparticles prepared by modified Pechini methodKolesnikov Ilya, Tolstikova Daria ..................................................................... 72

Study of the ‘memory effect’ at breakdown in argon and argon-nitrogen mixtureKorshunov Artem .............................................................................................. 73

Detailed ultrafast transient absorption study of CuCl42- complex in acetonitrile

Mereshchenko Andrey ....................................................................................... 74

Experimental study of electrical breakdown in a long discharge tubeOleinik Yuriy, Shishpanov Alexander ................................................................ 75

Study of the unique copper-containing biomineral from endemic Baikal Lake sponges by synchrotron radiationPetrova Olga .................................................................................................... 76

Study of instrument function of optical digital spectrographSavinov Sergey .................................................................................................. 77

Effect of F-doping on photocatalytic activity of titaniaShaytanov Leonid .............................................................................................. 78

Effect of the shape and orientation of filler particles in polymer materials on scattering studied by IR spectroscopySitnikova Vera ................................................................................................... 79

Design of a high definition monochromatorSolovev Ivan ...................................................................................................... 80

Two-photon transitions with cascades and two-photon level widthsZalialiutdinov Timur ......................................................................................... 81

Verification of two independent models for spectroscopic determination of the H2, HD, D2 partial densities in non-equilibrium hydrogen-deuterium plasmasZhukov Alexey ................................................................................................... 82

G. Theoretical, Mathematical and Computational Physics ........................ 83

Long-range rapidity correlations in a two-component modelAndronov Evgeny .............................................................................................. 84

132

The renormalization of spin-wave spectrum in three-dimensional antiferromagnetic with dipolar interactionBatalov Lev ....................................................................................................... 85

Some aspects of the fractional derivatives application in biophysical modelsBatalova Anastasiya .......................................................................................... 86

Equation of state of high density matter in the model of Nambu-Jona-LasinioBelyaev Vasiliy .................................................................................................. 87

Streaking of near-threshold photoelectrons produced in laser-assisted attosecond photoionizationBozhevolnov Astislav......................................................................................... 88

Renormalization group analysis of the inertial-range behaviour of a passive vector field in a random shear flowGulitskiy Nikolay ............................................................................................... 89

Solution of the time-dependent Dirac equation for the U91+(1s) – U92+ collision with the partial wave expansionIvanova Irina ..................................................................................................... 90

Splint in case of special embeddingsKakin Polina ..................................................................................................... 91

Higher order asymptotics and critical exponents in the φ3 theoryKalagov Georgii ................................................................................................ 92

Effective models for the radial Regge trajectoriesKatanaeva Alisa ................................................................................................ 93

Critical behavior of the O(n)-φ4 model with an antisymmetric tensor order parameterLebedev Nikita .................................................................................................. 94

Calculations of excitation and pair-creation probabilities in low-energy U92+ − U91+(1s) collisions in the monopole approximation Maltsev Ilia ....................................................................................................... 95

Spectral properties of quasi-periodic Schrodinger equationMartemyanov Andrey ........................................................................................ 96

133

Difference in using rapidity and pseudo-rapidity windows for <PT>:Nch correlations in pp collisions with PYTHIA8 event generatorNeverov Dmitry ................................................................................................. 97

Change of a chemical composition of an herb of Achillea millefolium under the influence of an anthropogenic factor Oleneva Yu.G. .................................................................................................. 98

Calculation of self-energy diagrams in the φ4 theory with help of recurrence relationsArtem Pismenskiy .............................................................................................. 99

Computersimulation of Self-Association Processes In Gemini and Monomeric Surfactant SolutionsRaev Dmitriy ................................................................................................... 100

Dual kinetic balance method in finite-basis-set expansions for axially symmetric Dirac equationRozenbaum Efim .............................................................................................. 101

Canonical formalism for embedding theory with partial gauge fixingSemenova Elizaveta ........................................................................................ 102

Exterior complex scaling method in TDDFT: HHG of Ar atoms in strong laser fieldsSosnova Ksenia ............................................................................................... 103

Investigation of stability of solutions of 5-dimensional cosmological modelTuzov Nikolay .................................................................................................. 104

E-teaching and remotely attended seminars: a live demonstrationUlmer Anatoli .................................................................................................. 105

H. Biophysics ................................................................................................. 107

Conformation and molecular characteristics of poly-2-acrylamido-2-methyl-propane tsetilammoniya in solutionAkhmadeeva Liliya, Podsevalnikova Anna, Lebedeva Elena, Mikhailova Mariya ....................................................................................................... 108

Study of DNA interaction with the metallized diphtalocyanines Alekseev Georgii ............................................................................................. 109

134

Models of DNA Interaction With Ruthenium Compounds Containing Biological Active LigandsKozhenkov Pavel ............................................................................................. 110

UVC-induced DNA destructions in vitroParr Marina .....................................................................................................111

Dielectric properties of liquid crystal complex on the base of YtterbiumSakhatskiy Aleksandr ...................................................................................... 112

DNA Interaction with divalent cations in the presence of EDTAUshkov Pavel, Paston Sofia ............................................................................ 113

DNA-Metallic Nanoparticles SystemsVarshavskiy Mikhail ........................................................................................ 114

I. Resonance Phenomena in Condenced Matter ........................................ 115

Behavior of Sodium Lauroyl Sarsosinate with Added Cosurfactants in Aqueous SolutionBubnov Philipp ................................................................................................ 116

Analisys of translational diffusion in binary system glycerol-heavy water by NMRBystrov Sergey ................................................................................................. 117

Investigation of the 1,5 T magnetic field inhomogeneity with dimensional projections of the phantomsDmitriev Roman .............................................................................................. 118

Hydrogen site occupancy in the Ti1-xNbxHy hydrides by proton NMRIevleva Valeriya ............................................................................................... 119

Comparative experimental and theoretical NEXAFS-study of Acenes and AzaacenesMichael Klues ................................................................................................. 120

Ab initio simulation of hydrogen diffusion paths in magnesium dihydrideKlyukin Konstantin.......................................................................................... 121

Study of radiation defects in paleontological objects by electron paramagnetic resonanceKultaeva Anastasia ......................................................................................... 122

135

A model of behavior of nuclear magnetization in alternating magnetic field of low frequencyKupriyanov Pavel, Zharinov Vyacheslav ........................................................ 123

Temperature features of hydrophobic and hydrophilic interactionsRabdano Sevastyan ......................................................................................... 124

Structure of hydrogen bonded complexes formed by strong CH-acids: NMR, IR, X-Ray and QM investigation of 1,1-dinitroethaneTupikina Elena ................................................................................................ 125

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