Plenary Talk Toward Atom-by-Atom Nanostructuring of Composite Nanomaterials Based …nanotr6.iyte.edu.tr/docs/conference-book/Oral... · 2010-06-04 · Toward Atom-by-Atom Nanostructuring

Toward Atom-by-Atom Nanostructuring of Composite Nanomaterials Based on Atomic Force Microscopy

S.Morita1, Y.Sugimoto1, M.Abe1

1 Graduate School of Engineering, Osaka University, Suita 565-0871, Japan

Abstract— We introduce a novel atom-by-atom creation and evaluation system based on the atomic force microscopy at room temperature(RT). It can identify chemical species of individual atoms and then manipulate selected atom species to the designed site one-by-one to createcomposite nanostructures consisted of many atom species at RT

Noncontact atomic force microscopy (NC-AFM) [1,2] based on the frequency modulation (FM) detection method can now not only image individual atoms but also construct atom letters using the atom manipulation method. Therefore, the NC-AFM is the next generation atom tool following the well-known scanning tunneling microscopy (STM). The NC-AFM, however, has the advantages that it can image even insulating surfaces with atomic resolution and also measure the atomic force itself between the tip-apex outermost atom and the sample surface atom. Noting these advantages, we have been developing a novel atom-by-atom creation and evaluation system based on the NC-AFM. It can identify chemical species of individual atoms [3] and then manipulate selected atom species to the designed site one-by-one to create composite nanostructures consisted of many atom species at room temperature (RT) [4] as shown in Fig.1. In this review talk, we will introduce our results toward atom-by-atom creation and evaluation of composite nanostructures based on the NC-AFM at RT.

To identify chemical species, we developed the site-specific force spectroscopy at RT by compensating the thermal drift using the atom tracking. Thus we obtained the precise site-specific frequency shift curves and then converted them into the short-range force curves of selected Sn and Si atoms, respectively. Then using the atom-by-atom force spectroscopy at RT, we succeeded in chemical identification of intermixed three atom species in Pb/Sn/ Si(111)-(r3xr3) surface [3]. Besides we found the lateral atom interchange phenomenon at RT, which enables us to exchange embedded heterogeneous atoms [4]. By combining this phenomenon with the vector scan, we constructed the embedded atom letters “Sn” consisted of substituted Sn atoms embedded in Ge atoms at RT [4] as shown in Fig.2.

In addition to the above results, today we will introduce our recent results on force mapping, another kind of the embedded atom letters “Si” created by the advanced single atom pen method [5] as shown in Fig.3, and the simultaneous evaluation of the force and current at the atomic scale using the combined AFM/STM.

*Corresponding author: [email protected] [1] S. Morita, R. Wiesendanger, and E. Meyer (eds.); “Noncontact Atomic Force Microscopy”, Springer, NanoScience and Technology, 2002. [2] S. Morita, F. J. Giessibl, and R. Wiesendanger (eds.); “Noncontact Atomic Force Microscopy”, Vol.2, Springer, NanoScience and Technology, 2009. [3] Y. Sugimoto, P. Pou, M. Abe, P. Jelinek, R. Pérez, S. Morita, and O. Custance, Nature, 446, 64 (2007). [4] Y. Sugimoto, M. Abe, S. Hirayama, N. Oyabu, O. Custance, and S. Morita, Nature Materials, 4, 156 (2005). [5] Y. Sugimoto, P. Pou, O. Custance, P. Jelinek, M. Abe, R. Pérez and S. Morita, Science, 322, 413 (2008).

Figure 2: Embedded atom letters “Sn” constructed by lateral atom interchange manipulation at RT

Figure1: Schematic models and experimental results on (a) atom imaging, (b) chemical identification of intermixed individual atoms, (c) embedded atom letters constructed by lateral atom interchange manipulation and (d) embedded atom letters constructed by vertical atom interchange manipulation using the interchangeable single atom pen based on the atomic force microscopy at room temperature

Figure 3: Embedded atom letters “Si” constructed by vertical atom interchange manipulation using the interchangeable single atom pen based on the atomic force microscopy at room temperature at RT

Plenary Talk

<<145>>

��

�� !"��#�� $��% ��

!��#$%&#$!"��'�� (�� '�� ' �'��)��*�� +�� !�� '�� #$%�� '�� '�� '�� ,� �'�� +��

�� * ��*�� '�� +�� +�-�!�� +�-��.��

�

��/�� !"� �� *�� * �� )�� '� �� * �� +� �� *�� 0�� 1��'�� +� �� '�� ' �'� �� 2�� 1��*�� 3�!�� '�� !�� '� �� '�� *�� '��1 �� +� ��4 �'� �� 5�� '�� '� �� ' ��0�� '�� * ��+� �� '�� *�� -�� 4� �� +� �� '� �� '�� '�� * �� +�� '�� !��'�� ! 6"� �� '��'�� +� �� '� �� 7�� +�7�� -�� '�� '�� !�� * �� 7�� +� � !� �� '�� /��+� �� *��*�� !� ��4�� )�� * �� 0�� *�� *�� '�� !+�� !�� *� �� '�� 89:� ; '�� '�� !�

�� +� �4�� 0�� +� *�� +�� '�� '�� '�� 8<:� ,� �'� �� *�� +� �� '�-�!�� +��'�� +�-��+�.�� 2�� =�� *�� '��

��$ '�� >� �� '��/��)� ��*��4�*�� ),=0)�7��.��5��)=�.�9?@)AB@��

Oral Presentation, Theme I : Nanoscale Characterisation, Nano-imaging, Nanoscopy, Nano-metrology

6th Nanoscience and Nanotechnology Conference, �zmir, 2010 146

Improve d localization of cellular membrane receptors using combined fluorescence microscopy and simultaneous topography and recognition imagi ng

M Duman1*, M Pfleger1, R Zhu2, C Rankl3, L A Chtcheglova1, I Neundlinger1, B L Bozna1, B Mayer1,2, M Salio4, D Shepherd4, PPolzella4, M Moertelmaier3, G Kada3, Andreas Ebner1,2, M Dieudonne5, G J Scheutz1, V Cerundolo4, Ferry Kienberger3 and Peter

Hinterdorfer1,2 1Institute for Biophysics, University of Linz, Altenbergerstrasse 69, A-4040 Linz, Austria

2Christian Doppler Laboratory for Nanoscopic Methods in Biophysics, Institute for Biophysics, University of Linz, Altenbergerstrasse 69, A-4040 Linz, Austria

3Agilent Technologies Austria GmbH, Aubrunnerweg 11, A-4040 Linz, Austria 4Cancer Research UK Tumor Immunology Group, The Weatherall Institute of MolecularMedicine, Nuffield Department of Medicine, University

of Oxford, Oxford OX3 9DS, UK 5

Agilent Technologies Belgium, Wingepark 51, Rotselaar, AN B-3110, Belgium

Abstract-Here we present a new platform of combined fluorescence and simultaneous topography and recognition imaging (TREC) for improved localization of cellular receptors. Using TREC on the inverted light microscope, the recognition sites of cell recep tors were detected in recognition images with domain sizes ranging from ~25 to ~160 nm, with the smaller domains corresponding to a

single CD1d molecule.

Fluorescence microscopy has become an important tool for localizing receptor/ligand recognition in living cells. However, the lateral and axial resolutions are typically limited by the optical elements in the microscope, as well as the diffraction limit of light, and result in ~200 nm resolution. Recently, higher resolution optical techniques have been introduced [1, 2], achieving a lateral resolution of 10–30 nm. However, optical techniques still cannot provide any information about the sample topography. By using recently developed simultaneous topography and recognition imaging technique (TREC), atomic fo rce microscopy (AFM) yields a topographical image and a separate map of recognition sites from a single scan, with a lateral resolution of 1.5 nm on S-layers [3] and 5 nm on cell surfaces [4].

In the first part of this study, the performance of the combined AFM/epi-fluorescence microscope system has been tested. Green fluorescent protein (GFP)-labeled human sodium-glucose cotransporter (hSGLT1) expressed Chinese Hamster Ovary (CHO) cells and endothelial cells from mouse Myocardium-stained with phallo idin-rhodamine were used as cell systems.

Figure 1. Overlay fluorescence and topography AFM images.

The topographical image revealed details of the assembly and organization of F-act in filaments, in particular globular F-actin-forming bundles with heights of ~20 nm were observed at the outer part of the cell and nicely overlapped with the F actin distribution in the fluorescence image (figure 1).In the second part, we introduce a new platform of combined TREC and epi-fluorescence microscopy imaging to detect the

density, distribution and localization of YFPlabeled CD1d molecules on �-galactosylceramide (�GalCer)-loaded THP1 cell surface. Receptor patches were observed as dark spots on the recognition images, with the diameter of the dark spots ranging between 25 and 160 nm (figure 2(f)).

Figure 2. Simultaneous epi-fluorescence microscopy, topography AFM and recognition imaging:

The present work demonstrates epi-fluorescence microscopy becomes more powerful when combined with TREC imaging.While fluorescence imaging can be used to determine the overall expression level and the distribution of receptor sites on the cell surface, simultaneous topography and recognition imaging allows exploring cell shapes, membrane domains and an accurate localizat ion of receptor binding sites This new platform allows sensing fluorescence, topography and recognition of receptor binding sites on cellular surfaces under physiological conditions with nanoscale resolution.

*Corresponding author: [email protected]

[1] K.I. Willing et al, Nature 440 935–9 (2006). [2] E. Betzig, et al , Science 313 1642–5 (2006). [3] J. Tang et al, Nano Lett. 8 4312–7 (2008). [4] L. Chtcheglova et al, Biophys. J. Biophys.Lett. 93 L11–3 (2007).



Advantage and Disadvantage in Drug Delivery Systems

G. Dikmen1, L. Genç2, G. Güney3

1 Anadolu University, Institute of Science, Department of Nanotechnology, 26470, Eskişehir, TURKEY 2 Anadolu University, Faculty of Pharmacology, Department of Pharmaceutical Technology, 26470, Eskişehir, TURKEY

3Anadolu University, Faculty of Science, Department of Biotechnology, 26470, Eskişehir, TURKEY

Abstracts- We aimed to compare different nanoparticles in drug delivery systems. We also tired to show the advantages and disadvantages of the preparation methods of these systems.

Nanotechnology, systems-devices manufactured at the molecular level, is a multidisciplinary scientific field undergoing explosive development. A part of this field is the development of nanoscaled drug delivery devices [1]. Nanotechnology advances in drug delivery deal with the development of synthetic nanometer sized targeted delivery systems for therapeutic agents of increased complexity, and biologically active drug products [2].

Nanomedicine is defined as the application of nanotechnology to achieve breakthroughs in healthcare. The development of drug delivery systems has improved the therapeutic and toxicological properties of existing chemotherapies and facilitated the implementation of new ones [3].

Currently used drug delivery systems, such as liposomes, micelles, nanoemulsions, polymeric nanoparticles and manyothers demonstrate a broad variety of useful properties [4].

The successful implementation of nanoparticles for drug delivery depends on their ability to penetrate through several anatomical barriers, sustained release of their contents and their stability in the nanometer size. However, the scarcity of safe polymers with regulatory approval and their high cost have limited the wide spread application of nanoparticles to clinical medicine [5].

To overcome this limitation the drawbacks associated to the traditional colloidal systems [6], such as emulsions, liposomes and polymeric nanoparticles, solid lipid nanoparticles (SLN®) and nanostructured lipid carriers (NLC®) were developed [7]. The main difference between SLN and NLC is the fact that the concept of these latter is performed by nanostructuring the lipid matrix, in order to increase the drug loading and to prevent its leakage, giving more flexibility for modulation of drug release.

A.Liposome B. Miceles

C. Nanoparticle D. Solid Lipid Nanoparticle

Figure 1. Various nanostructures used in drug delivery systems.

In this study diagnosis and treatment of various diseases with different drug carrier systems have been examined. Furthermore, advantages and disadvantages of the preparation and implementation stages of drug formulations, as well as their detection systems have been compared each other.

*Corresponding Author: [email protected]

[1] C.Kiparissides and O. Kammona, 2008. Nanotechnology advances in controlled drug delivery systems. Current Topics in Solid State Physics, 12, 3828-3833. [2]O. Kayser, A. Lemke, N. Hernandez-Trejo, 2005. The Impact of Nanobiotechnology on the Development of New Drug Delivery Systems.Current Pharmaceutical Biotechnology, 6(1). [3]Gorka Orive, Rosa Maria Hernandez, Alicia R. Gascon, Jose Luis Pedraz, 2005. Micro and nano drug delivery systems in cancer therapy. Cancer Therapy, 3, 131-138. [4]Vladimir P. Torchilkin, 2006. Multifunctional nanocarriers. Advanced Drug Delivery Reviews, 1532-1555. [5] Mukherjee S., Ray S. And Thakur S.R., 2009. Solid Lipid Nanoparticles: A Modern Formulation Approach in Drug Delivery System. Indian Journal of Pharmaceutical Sciences, 71(4), 349 - 358. [6] Souto, E. B., Wissing, S. A., Barbosa, C. M., Müller, R. H., 2004. Development of a controlled release formulation based on SLN and NLC for topical clotrimazole delivery, Int. J. Pharm., 278, 71 - 77. [7]Souto, E. B., Gohla, S., Müller, R. H., 2005. Rheology of nanostructured lipid carriers (NLC®) suspended in viscoelastic medium, Pharmazie 60, 671 - 673.



Figure1: (a) High resolution AFM phase image (b) Raman spectra evaluated from the 2D spectral array (c) Raman image showing the distribution of alkyd (bright areas) and acrylic latex (dark areas). [1] P. Lasch, A. Hermelink. and D. Naumann, The Analyst, 1-9,

(2009). [2] A. Jungen, V. N. Popov, C. Stampfer, C. Durrer, S. Stoll,

and C. Hierold Physical Review, 75, 405-410, (2007). [3] U. Schmidt, S. Hild, W. Ibach and O. Hollricher, Macromol.

Symp. 230, 133-143 (2005). [4] T. Dieing and O. Hollricher, Vibrational Spectroscopy, 48,

22-27 (2008). [5] U. Schmidt, W. Ibach, H. Fischer, and O. Hollricher, A Supplement to Spectroscopy, 32-38 (2009).

Characterization of Multi-Component Materials on the Sub-Micrometer Scale Confocal Raman SPM Studys

U. Schmidt*, T. Dieing, F. Vargas WITec GmbH, Lise-Meitner Str. 6, Ulm 69081, Germany, www.witec.de

Abstract— The characterization of heterogeneous systems on the sub-micrometer scale continues to grow in importance and to impact key applications in the field of materials science and nanotechnology. The combination of various characterization

techniques in one instrument provides structural and chemical information from the same sample area, leading to a deeper understanding of multi-component materials and to the design of new heterogeneous materials. Aim of this contribution is to

present the combination of various techniques in combination with key application examples from nanotechnology.

Knowledge about the morphology and chemical composition of heterogeneous materials is crucial for the developments of new material properties for specific applications. In the past two decades, SPM was one of the main techniques used to characterize the morphology of nano-materials. On the other hand, Raman spectroscopy is known to be used to unequivocally determine the chemical composition of a sample. By combining the material sensitive Raman spectroscopy with high resolution confocal optical microscopy, the analyzed sample volume can be reduced below 0.02 μm3, thus leading to the ability to acquire Raman images with diffraction limited resolution [1, 2]. The combina-tion of confocal Raman microscopy with Scanning Probe Microscopy (SPM) is a breakthrough in microscopy. Using such a combination, the high spatial and topographical resolution obtained with an SPM can be directly linked to the chemical information provided by confocal Raman spectroscopy [3].

To demonstrate the unique capabilities of the confocal Raman-SPM combination, an emulsion consisting of alkyd and acrylic latexes has been analyzed. Alkyds and acrylics are used as binders in paints and coatings. These materials produce a shiny, hard finish that is highly water-resistant. Figure 1a shows a 10x10 μm2 AFM phase image recorded on a dried alkyd-acrylic latex sample. Two different phases can be clearly distinguished: a texture-less phase, which forms elliptical structures and another phase consisting of spherical particles. The diameter of these particles is approximately 250 nm. The same sample area was measured in Raman spectral imaging mode. In this imaging mode a 2D array consisting of 200x200 Raman spectra was acquired with an integration time of less than 30 ms/spectrum (total acquisition time less than 30 min.). Figure 1b shows the characteristic Raman spectra calculated from the multi-spectrum file using cluster analysis [4]. The diffraction limited Raman image is presented in Fig. 1c, showing that the elliptical texture-less phase corresponds to alkyd (bright areas of the image) and the spherical fine structure to acrylic latex (dark areas of the image).

Further examples from various fields of applications will be presented.

*Corresponding author: [email protected]



Topography

2nd resonance Δf

Error of Δf1 Δf2

Sensitivity Comparison of First Two Flexural Modes in bimodal non-contact Atomic Force

Microscopy Ramazan Sahin1*, Umit Celik2, H. Ozgur Ozer1, Ahmet Oral3

1Department of Physics Engineering, Istanbul Technical University, Istanbul 34469, Turkey 2Department of Material Science and Engineering, Istanbul Technical University, Istanbul 34469, Turkey

3Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul 34956, Turkey

Abstract- We builded up a Multifrequency non-contact Atomic Force Microscope with two digital Phase Locked Loops (PLL) in order to observe frequency shifts of first two modes. Quantitative comparisons of frequency shifts of first two flexural modes of non-

contact Atomic Force Microscope will be held in this study.

Recently, Atomic Force Microscopy (AFM) has been

experiencing a new evolution from single frequency excitation to multifrequency excitation and there are reports in the literature on the theory of this method [1]. Multifrequency AFM has shown noticeable improvement on sensitivity of the microscope with a high spatial resolution demonstrated on a variety of heterogeneous materials. Compositional maps of conjugated molecular materials show a contrast an order of magnitude higher than one achieved in amplitude modulation AFM [2]. Stark et. al. have used this method in order to minimize cross-talk between mechanical and electrical interactions while imaging charge patterns in electrets [3].

In nc-AFM, a frequency modulation (FM) technique is applied in order to maintain the cantilever vibrating at its eigen-frequency f0 by means of a self-excitation generator. Hence the acronym FM-AFM relates explicitly to the NC-AFM detection method. The most interesting feature of NC-AFM is that using of a highly resonant oscillator leads to a better sensitivity to the surface, as the thermal noise of the oscillating probe diminishes as [4]. Detecting frequency shifts, especially in high Q oscillators are much faster, easier and less noisy compared to the AM-AFM.

Typically bimodal operation gives better constrast in AM-AFM. Non-contact AFM on its own also gives good results In this study, our main motivation was to develop bimodal operation for non-contact AFM in ambient conditions. For this purpose, we modified our AFM with two digital PLL and additional low-pass, high-pass filters. We carried out variety of experiments by changing amplitude ratio (A1/A2) of first two resonances of the cantilever. One of the PLLs was locked to the first resonance frequency of the cantilever and used to give the frequency shift as the feedback signal for the regulation of the tip-sample separation. While the shift in the first resonance frequency was used to generate the topographic image of the sample surface, other PLL was locked to the second resonance frequency and we obtained the frequency shift and dissipation maps of the surface. All experiments were performed using commercial AFM [5]. Figure shows such simultaneous scans of peptides on Au (111), all revealing the features on the surface.

Figure 1. Peptides on Au(111) using bimodal nc-AFM. f1=89 kHz

and f2=554 kHz

In recently published paper, Kawai et. al. showed that shift in the second resonance frequency (f2) is an order of magnitude higher than shift in first resonance frequency (f1) while first resonance frequency is used for feedback signal in quasi-constant height mode where the feedback loop gain was adjusted such that the topographic corrugation amplitudes were quite small [6]. We also found repeatedly similar results in bimodal non-contact AFM in some experiments on Blu-ray disc such as shown in Figure 2. Feedback loop gain was low enough to reveal the features in the error signal of Δf1 . The corrugation amplitude in Δf2 is as large as 30 times that in Δf1.

Figure 2. Bimodal nc-AFM images of Blu-ray disc. f1=88546 Hz,

f2=460180 Hz For the true comparison of sensitivity of first two resonance

frequencies, one must turn the feedback loop off and observe real shifts in resonance frequencies. In this work, sensitivities of first and second resonances will be compared during constant height scanning.

This study was supported by TUBITAK and TUBA. *[email protected] [1]Jose R.Lozano and R. Garcia Phys. Rev. Lett. 100, 076102

(2008) [2]N.F. Martinez, S. Patil et al. Appl. Phys. Lett. 89, 153115

(2006) [3]R.W. Stark, N.Naujoks et al. Nanotechnology 18, 065502

(2007) [4]Y.Martin, C.C. Williams et al. J. Appl. Phys. 61, 4723 (1987) [5] Nanomanyetik Bilimsel Cihazlar Ltd. Şti. Ankara/Turkey [6]S. Kawai, Thilo Glatzel et al. Phys. Rev. Lett. 103, 220801

(2009) 100 nm



Atom Manipulation and Force Spectroscopy on Cu(110)-O Surface with Low Temperature Atomic Force Microscopy

Yasuhiro Sugawara Department of Applied Physics, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan

Abstract- We investigate the forces and the potential energy in AFM lateral manipulation for a top single Cu atom

(super Cu atom) on the Cu(110)-O surface. The energy barrier to manipulate the super Cu atom laterally on the surface strongly depends on the chemical nature of tip-sample interaction.

Manipulation of single atoms and molecules is an innovative experimental technique of nanoscience. So far, a scanning tunneling microscopy (STM) has been widely used to fabricate artificial structures by laterally pushing, pulling or sliding single atoms and molecules. However, the driving forces involved in manipulation have not been measured. Recently, an atomic force microscopy (AFM) has been also used to manipulate single atoms and molecules. Atom manipulation with an AFM is particularly promising, because it allows the direct measurement of the required forces.

In the previous experiments, we investigated the forces in AFM lateral manipulation for a top single Cu atom (super Cu atom) on the Cu(110)-O surface. In the case of Cu-adsorbed AFM tip, the super Cu atom on the surface was pulled at a lateral tip position on the adjacent binding site. In contrast, in the case of O-adsorbed AFM tip, the super Cu atom was pushed over the top of the super Cu atom. These experimental results suggest that the forces (attractive or repulsive forces) to move an atom laterally on the surface strongly depend on the atom species of the AFM tip apex and the surface.

In this study, we investigate the full tip-sample potential distribution to clarify the manipulation process depending on the chemical nature of tip-sample interaction.

All experiments were performed by using noncontact AFM at 78 K. Prior to the measurements, the AFM tip apex was coated by Cu or O atoms in situ by slightly making a tip-sample mechanical contact on the Cu(110)-O surface. The tip-sample potentials were determined form the frequency shift versus distance curves by mathematical analysis (Fig. 1). When tip approached the surface, in the case of Cu-adsorbed AFM tip, potential energy at the adjacent biding site decreased, while in the case of O-adsorbed AFM tip, potential energy at the super Cu atom site increased. For the first time, we found that the energy barrier to manipulate the super Cu atom laterally on the surface strongly depended on the chemical nature of tip-sample interaction. Furthermore, we discuss the pathways for moving the super Cu atom on the surface.

Figure 1. (a) AFM image and (b) two-dimensional map of force

curves measured with O-adsorbed tip on Cu(110)-O surface. *[email protected] [1] M. Ternes et al., Science, 319, 66 (2008).



Figure 1: Scheme of the experimental set-up. The laser arm (laser-polarizer-compensator) and the detector arm (detector-analyzer) are operated at a fixed angle of incidence. The AFM tip, which is coated with a thin metal layer, is scanning the sample while the ellipsometer measures simultaneously in null-ellipsometer conditions.

Optical Microscopy at the Nanoscale Mine Memesa,1,2* Peter Schön,1,2 Davide D. Tranchida3, Holger Schönherr3, Julius G. Vancso1,2

1Materials Science and Technology of Polymers, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands2MESA+ Institute for Nanotechnology, University of Twente, The Netherlands

3Present address: Department of Physical Chemistry, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen,Germany

Abstract— We report combination of an atomic force microscope (AFM) and an ellipsometer to obtain near-field optical images. This technique is non-destructive, economical and provides information about the lateral distribution of optical density heterogeneities. In addition to optical imaging of topological features, our approach would yield information about the optical properties (lateral distribution of refractive index) of materials down to the nm scale which holds promise to provide crucial,

long-needed information for preparation and characterization of new optical materials.

In nanotechnology and bio-nanotechnology there is a strong need to access imaging techniques to visualize materials from mm down to nm length scales. Nanometer scale optical properties are interesting in fields of resist layers, ultrathin coatings, nanocomposites, biological polymer platforms, sensors, and devices. Atomic force microscopy (AFM) which is an invaluable technique for studying the surfaces and molecular interactions on the nanometer scale enabled visualization and study of soft matter across the length scales [1]. Optical methods have been used in polymer science to investigate, for ex, morphology, phase transitions, orientation (via birefrigance), mobility, diffusion, etc. Diffraction of light prevents optical microscopes from having spatial resolution beyond a value comparable to the wavelength of the probing light [2]. An optical microscope where a nano-sized metallic probe tip scans the sample surface to form an image with a resolution much better than the diffraction limit was first demonstrated by Kawata’s group [3]: An apertureless near-field scanning optical microscope (SNOM) where a metallic scanning tunneling microscope (STM) tip which is illuminated with evanescent light is scanned over the sample. The excitation of the localized modes of surface plasmon polaritons (SPP) at the metallic tip generates a nano-sized light spot at the apex of the nano-tip. When this light spot is used as the light source of an optical microscope extremely high spatial resolution can be obtained. Although existing SNOM techniques offer nanoscale resolution, using optical, tapered fibers as probes, high signal-to-noise ratios, specimen damage issues and complex instrumentation prevent SNOM from being a widespread characterization tool [4,5]. In this work, we report combination of an atomic force microscope (AFM) and an ellipsometer to obtain near-field optical images [6]. The schematic representation of the experimental set-up is given in Figure 1. A metal-coated AFM tip is scanning the sample which is prepared on a glass substrate. The tip is illuminated with the laser coming from the ellipsometer. The ellipsometer is operated in null-ellipsometry conditions, where all the light reaching the detector is canceled. While the AFM tip scans the sample, the interaction of the localized surface plasmon polaritons with the sample changes the null-ellipsometry conditions and light is detected at the detector. The optical image collected by the ellipsometry detector simultaneously with the topographic image of the AFM will provide additional optical information on the sample properties. We first studied gold nanoparticles that are embedded in a poly (methyl methacrylate) matrix. We next want to extend

this study to different metal nanoparticles, such as silver, in a polymer matrix. The results obtained from these studies will be presented. This technique is non-destructive, economical and provides information about the lateral distribution of optical density heterogeneities. In addition to optical imaging of topological features, our approach would yield information about the optical properties (lateral distribution of refractive index) of materials down to the nm scale which holds promise to provide crucial, long-needed information for preparation and characterization of new optical (e.g. photonic) materials. This work is part of the research program of the Dutch Polymer Institute (DPI), project #695. *Corresponding author: [email protected] [1] S. M. Flores and J. L. Toca-Herrera, Nanoscale 1, 40 (2009). [2] S. Kawata, Y. Inouye and P. Verma, Nature Photon. 3, 388 (2009). [3] Y. Inouye and S. Kawata, Opt. Lett. 19, 159 (1994). [4] S. Aubert, A. Bruyant, S. Blaize, R. Bachelot, G. Lerondel, S. Hudlet and P. Royer, J. Opt. Soc. Am. B-Opt. Phys. 20, 2117 (2003). [5]. L. Gomez, R. Bachelot, A. Bouhelier, G. P. Wiederrecht, S. H. Chang, S. K. Gray, F. Hua, S. Jeon, J. A. Rogers, M. E. Castro, S. Blaize, I. Stefanon, G. Lerondel and P. Royer, J. Opt. Soc. Am. B-Opt. Phys. 23, 823 (2006). [6] P. Karageorgiev, H. Orendi, B. Stiller and L. Brehmer, Appl. Phys. Lett. 79, 1730 (2001).



Spectral Scattering Detection for Single Particle Detection and Size DiscriminationAbdulkadir Yurt1*, George G. Daaboul2, Xirui Zhang2 and M. Selim Unlu2, 3

1 Material Science and Engineering, Boston University, Boston, MA 02215, USA 2Biomedical Engineering, Boston University, Boston, MA 02215, USA

3 Electrical and Computer Engineering, Boston University, Boston, MA 02215, USA

Abstract-We investigate an op tical imaging technique which is capable of detecting and size discriminating single nanop articles which are below the diffraction limited resolution. Our technique employs wide-field detection and processing of interferometric signal due to the elastically

scattered light and reference light at different visible wavelengths. The simulation and experimental results prove the technique to be promising for fast, high throughput and label-free bio-sensing application for nanoparticles in the range of 50nm-150nm in diameter.

Nanoparticle detection has gained considerable attention in biomedical research [1], material characterization [2], national security [3] and in other fields. Recently various optical techniques have been suggested for label-free single part icle detection and size determination [4, 5]. Although these optical techniques offer sensitive detection many challenging issuesare yet to be overcome such as low throughput, cost-effectiveness and reliab ility etc.

In this work we introduce a robust optical imaging method which is capable of detecting and size discriminating of nanoparticles that are very small comparing the wavelength of incident light. The technique is based on spectral measurement of interference of the elastically scattered light from nanoparticles and reflected reference light. The proposed optical setup comprises of a telescopic imaging system with a high NA achromatic object ive and CCD in addition to several led sources at different peak wavelengths in Kohler illumination configuration.

Figure 1. The Optical Setup . L: Lens, BS: Beam splitter. Brown arrows show scattered and blue arrows shows only normally reflected light from slab.

We first study the problem theoretically. A modified Mie Theory [6] is in itially employed to calculate the scattered far-field and the result is compared with Rayleigh Theory (RT). It is seen that the error for size determination is less than 5% for �� C&A and it decreases for smaller particles.Therefore the RT is favored due to its simplicity and low computation cost. According to RT the polarizability of a spherical particle is:

(1)

Where r is the particle ra��+� Dp is the particle permittiv ity �� Dm is the medium permittiv ity. In the conventional dark �� '��*�� *�� EFE2

In order to study the optical technique we model a low index material whose index is close to biological materials. We choose polystyrene (PS) spherical beads with diameters of 70nm, 100nm and 150nm as our test sample. The beads are sparsely dispersed on a wafer of which has a 500nm th ick silica layer on top.

is quite small to be measured for particles below hundred nanometers whereas the interferometric s�'�� *�� EFE�thus decreasing detection limit and increasing dynamic range. Assuming an ideal Kohler Illumination scheme we deduce the intensity which each single nanoparticle sense is spatially

coherent due to the quasi-homogenous field properties [7]. We apply Angular Spectrum Representation (ASR) [8] to calcu late the detected fields with spectral background signal on the CCD due to particles on the focal plane of the objective.

450 500 550 600 6500.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8Detected Signal

Wavelength [nm]

Inte

nsity

[au]

no particled = 70nmd = 100nmd = 150nm

Figure 2. Simulated spectral response with different size of PS beads and bare substrate. (d: diameter)

As expected from RT the detected signal decreases for longer wavelengths. For experimental verification we choose three led colors at peak wavelengths: 470n m, 525nm and 625nm. We successfully detect and size-sort each of several thousands of particles within seconds. The simulation and experimental results also match quite well. The experimental SNR suggests that even smaller particles down to 50nm are within our detection range.

In summary, we report a high throughput, fast, cost-effective imaging technique for single particle detection and size discrimination. We expect the technique to be a promising tool for label-free sensing of small b ioparticles such as virions and proteins in future. This work was partially supported by ARL/Photonics Center BU Grant.*Corresponding author: [email protected][1] Patolsky F, et al. PNAS 101:14017-14022 (2004) [2] Doering, R, et al. CRC Press: Boca Raton, FL, (2007) [3] Anderson, B, et al. Springer: New York, (2006) [4] Mitra A, et al. ACS Nano 4,[5] Vollmer F, et al. PNAS 2008 105: 20701-20704.

1305-1312 (2010)

[6] Johnson BR, J. Opt. Soc. Am. A 13, 326-337 (1996) [7] Mertz J,Greenwood Village, CO: Roberts and Company (2009) [8] Novotny L. et al.Cambridge University Press, Cambridge, (2006)



Nanometrology, Evaluation Techniques and Quality Control forHigh Accuracy Surface Measurement

M. Numan Durakbasa1, Pinar Demircioglu2, Mehmet Cakmakci3, Adriana Hornikova1

1 Vienna University of Technology, Institute of Production Engineering and Laser Technology, Vienna 1040, Austria2 Adnan Menderes University, Faculty of Engineering, Department of Mechanical Engineering, Aydin 09010, Turkey

3 Dokuz Eylül University, Faculty of Engineering, Izmir 35160, Turkey

Abstract- High accuracy surfaces are created nowadays by a large variety of manufacturing processes and techniques such as: CNC turning and milling, broaching, grinding, polishing, honing, electro chemical etching, etc. The most important parameters in determining the suitability of atechnical part are its compatibility, functionality, performance and corrosion resistance. The precise assessment of wear, friction and miniaturization demands creation of nanometer scaled surface structures, surfaces with thin film deposition and ultra precision surface treatment with the utilization of new manufacturing and measurement instrumentation and techniques. These include micro and nanofabrication of surface patterns and topographies by the use of laser machining, photolithographic techniques, and electron beam and colloidal lithography to producecontrolled structures on technical surfaces in size ranging from 10 nm to 100 µm. At the time being 3D surface measurement is already proved to be an important tool in several areas of surface analysis including wear, indentation, topography, contact problems and functional behavior of surfaces. Following this experimental study, all measured surface parameters have been analyzed using the SPSS 15.0 (the Statistical Package for Social Science) statistically and with the mathematical model for the most important and commonly used Rz roughness parameter has been developed so that Rz = Rz (F, P, C, M), where F is feed, P is periodicity, C is contrast and M is material type.

Need for high precision surface measurement becomes more and more indispensable due to manufacturing tiny workpieces and structures. To achieve surface finishes and required parts tolerances within the sub-micrometer and nanometer field, it is necessary to incorporate very sophisticated instrumentation and metrology as early as in design step [1].

Here we have compared different measurement methods using contact and optical profilometers, alongside with results of surface roughness measurements on specimen having different geometrical shapes by means of the stylus type instrument as mechanical profilometer [2,3,4], and the infinite focus, and the confocal laser scanning microscopes as optical imaging techniques [5]. Measurement systems were used regarding their capabilities. Thus, many tests were made with them so as to clarify results of the comparison in “The Nanotechnology Laboratory of the Department for Interchangeable Manufacturing and Industrial Metrology”. Experiments were done by preparing flat-shaped specimen with different machining processes such as turning, grinding,and milling, and spherical-shaped specimen, which were steel balls of bearings. This experimental work utilized 15 flat-shaped conventionally machined samples with periodic and random profiles being of different roughness value classes, having either shiny or browned surfaces, and additional 6 steel balls with high precision technical surfaces.

An important role also play the chosen roughness parameters [6,7]. In our experimental study were evaluatedmost of the 2D and 3D roughness parameters, like Sa, Sq, Ssk,etc.. The 3D parameters give a more accurate picture of the surface variable, therefore it is possible to evaluate with higher precision the surface parameters according to the used machining technique. It is also necessary to understand which machining parameters influence more and which parameters are less influential [8].

Statistical results have proven that the Rz parameter isdependent on these variables, the periodicity, the type of material, the contrast, the type of production processes, thefeed and the type of machine as its independent variables. Feed, periodicity, contrast and the type of material well predicted values of the Rz parameter. The linear predictionequation for Rz parameter is given below:

Rz = -3.258 +38.059 * F + 4.495 * P + 0.906 * M – 1.500 * C where F is feed, P is periodicity, C is contrast and M is thematerial type.

Regression Standardized Residual210-1-2-3

Freq

uenc

y

50

40

30

20

10

0

Histogram

Dependent Variable: Rz

Mean =-3,98E-15�Std. Dev. =0,987�

N =234

Observed Cum Prob1,00,80,60,40,20,0

Expe

cted

Cum

Pro

b

1,0

0,8

0,6

0,4

0,2

0,0

Normal P-P Plot of Regression Standardized Residual

Dependent Variable: Rz

Figure. Distribution curves of Rz parameter with descriptive statistics obtained from measurement data [9]

We conclude that light optical methods have the advantage of operating without tactile contact and withapplication of modern data processing techniques results become available requiring only very short measuring times.

*Corresponding author: [email protected][1] Osanna, P. H., Durakbasa, M.N., Kräuter, L., 2008, “Industrial Metrology and Interchangeable Manufacturing under the Viewpoint of Nanotechnology and Nanometrology”, Bulgarian Academy of Sciences, Problems of Engineering Cybernetics and Robotics, Vol. 59, pp.60-73.[2] D. Whitehouse, “Comparison between stylus and optical methods for measuring surfaces”, Annals CIRP, 37(2), pp. 649–653, 1988.[3] K. Stout, Three Dimensional Surface Topography, Measurement,Interpretation, and Applications, Penton Press, 1988.[4] H. J. Pahk, K. Stout and L. Blunt, Report on Visit under Korea–UK Research Project Scheme, 1998.[5] http://www.leedsmicro.com/LEXT.asp[6] DIN EN ISO 4287:2009- Geometrical Product Specifications (GPS) -Surface texture: Profile method - Terms, definitions and surface texture parameters (ISO 4287:1997 + Cor 1: 1998 + Cor 2: 2005 + Amd 1: 2009)[7] Whitehouse, D.: Function Maps and the Role of Surfaces. Int. J. Mach. Tools Manufact. Vol. 41(2001), 1847-1851.[8] Osanna, P.H., N.M. Durakbasa: Concept for Computer Aided Non-contact Laser Roughness Evaluation of Engineering Surfaces. Proceedings of 7th International Symposium on "Laser Metrology Applied to Science, Industry and Everyday Life - LM-2002", Nowosibirsk, Russia, (Editors: Y.V. Chugui, S.N. Bagayev, A. Weckenmann, P.H. Osanna), The International Society for Optical Engineering, ISBN 0-8194-4686-6, 708-714, (2002).[9] Aksoy (Demircioglu) P.: Evaluation of High Precision Surface Structures by Contact Stylus and Non-Contact Optical Methods. PhD Thesis. TU-Wien, Austria, (2008).

Formatiert: Schriftart: (Standard)Times New Roman



Probing intrinsic energy barrier distribution of CoNi/Pd magnetic multilayers using magnetic force microscopy

Ozhan Ozatay1*,2, Thomas Hauet2, Sylvia Florez2, Jordan Katine2, Andi Moser2,

Jan-Ulrich Thiele2, Liesl Folks2, Bruce Terris2

1Department of Physics, Bogazici University, Istanbul 34342, Turkey 2Hitachi Global Storage Technologies, San Jose, CA 95135, USA

Abstract— We demonstrate a measurement technique with zero-applied magnetic field to deduce and spatially map the activation energy barrier distribution of strongly exchange-coupled magnetic-multilayer thin films, which is otherwise inaccessible with conventional methods in the presence of an applied magnetic field. Our technique involves the analysis of magnetic force microscopy images of magnetic microwires, whose magnetizations have been subject to thermal decay due to Joule heating from applied nanosecond scale current pulses. Fitting the results of such measurements on CoNi/Pd magnetic-multilayer microwires to a modified Arrhenius-Neel formalism yields an energy barrier distribution with 8% sigma, in good agreement with complementary fits of the switching-field-distribution measurements on patterned CoNi/Pd magnetic-multilayer islands.

The technological challenges of obtaining uniform switching characteristics in patterned magnetic nanostructures have been driving intensive research efforts to control the device- to- device performance variations [1,2]. While it is relatively easier to control extrinsic factors by modifying the patterning techniques used [2, 3] the spatial inhomogeneity of intrinsic magnetic properties, such as magnetization, exchange, anisotropy, and activation energy for reversal can be very difficult to probe and control.

Figure: Mapping energy barrier distribution in CoNi-Pd multilayer micro-wires. (a) A series of demagnetization attempts using 7.4 ns, 3.2V pulses. From left to right: MFM image of the saturated state, MFM image after the application of a pulse train with 1000 pulses, MFM image after the application of a pulse train with 10000 pulses. (b) The MFM image of the state after the application of 10000 pulses before threshold filtering (c) Magnetization decay as a function of number of pulses applied (blue dots). Simple Arrhenius- Neel exponential decay fit -red dotted curve and modified Arrhenius-Neel decay fit assuming 8% Gaussion distribution of energy barriers ( as shown in the inset)- blue dot-dashed curve. (d) The MFM image of the state after the application of 10000 pulses after threshold filtering In the case of an array of magnetic dots, one of the most important consequences of a finite distribution of intrinsic magnetic properties is the dot-to-dot reversal field variation. This so called switching field distribution (SFD) can lead to the misregistration of the information in both bit patterned media (BPM) recording and magnetic random access memory (MRAM). Gathering information about the SFD of strongly-exchange coupled films is of primary importance, since such

materials offering large exchange lengths (20-25 nm for [CoNi/Pd] multilayers are the ones that will most likely adapt a stable single-domain magnetic configuration when patterned into nanoscale memory islands. While in weakly exchange-coupled continuous granular magnetic media, the squareness of the magnetization reversal hysteresis loops directly reflects the SFD such information is not directly available from the hysteresis loop measurements of strongly exchange coupled magnetic thin films. Indeed the reversal mechanism of strongly exchange coupled film is that of nucleation in weakest anisotropy regions followed by rapid domain wall propagation. This implies that all nucleation volumes whose nucleation field is greater than the depinning field do not contribute to the reversal process of the full film. Therefore it is not possible to deduce the reversal energy barrier distribution of such regions from a direct macroscopic study of the magnetic properties of a strongly exchange coupled film. Here we demonstrate a technique to obtain a spatial mapping of the intrinsic energy barrier distribution for reversal in strongly exchange coupled magnetic multilayer thin films using magnetic force microscopy (MFM) imaging. This technique entails imaging of the gradual magnetization decay due to current pulse induced Joule heating in patterned micro-wires. After applying a systematic threshold filtering to the acquired images to quantify the amount of magnetization decay, the resulting data can then be fit to a modified Arrhenius-Neel exponential decay model assuming that the energy barriers for reversal have a Gaussian distribution and each nucleation volume behaves as a Stoner-Wohlfarth (S-W) particle. In this experiment we have applied this technique to determine the activation energy barrier distribution for reversal in [CoNi/Pd] perpendicular anisotropy magnetic multilayers. This quantitative information on energy barrier distribution together with spatial mapping is applicable for future nanoscale memories development such as patterned media recording, MRAM or racetrack memory. *Corresponding author: [email protected] [1] T. Thomson, G. Hu, B. D. Terris, Phys. Rev. Lett. 96, 257204 (2006). [2] J. M. Shaw, S. E. Russek, T. Thomson, M. J. Donahue, B. D. Terris, O. Hellwig, E. Dobisz, M.L. Schneider Phys. Rev. B 78, 024414 (2008). [3] O. Ozatay, P. G. Gowtham, K. W. Tan, J. C. Read, K. A. Mkhoyan, M. G. Thomas, G. D.Fuchs, P. M. Braganca, E. M. Ryan, K. V. Thadani, J. Silcox, D. C. Ralph and R. A. Buhrman, Nat. Mater. 7, 567 (2008).



Documents

Plenary Talk Toward Atom-by-Atom Nanostructuring of Composite Nanomaterials Based …nanotr6.iyte.edu.tr/docs/conference-book/Oral... · 2010-06-04 · Toward Atom-by-Atom Nanostructuring