In The Name of Allah
Scanning Tunneling Microscope
Pooria Gill
Ph.D. of Nanobiotechnology
Faculty of Medicine
Mazandaran University of Medical sciences
Image from an STM
Iron atoms on the surface of Cu(111)
Microscopy
Optical Microscopy
Scanning Electron Microscopy
Scanning Probe Microscopy
Scanning Probe Microscope
Atomic Force Microscope (AFM)
Electrostatic Force Microscope (EFM)
Magnetic Force Microscope (MFM)
Scanning Tunneling Microscope (STM)
Near-field Scanning Optical Microscope (SNOM)
History
The scanning tunneling microscope was developed at IBM Zürich in 1981 by Gerd Binning and Heinrich Rohrer who shared the Nobel Prize for physics in 1986 because of the microscope.
Gerd Binning Heinrich Rohrer
The STM is an electron microscope thatuses a single atom tip to attain atomic resolution.
Scanning Tunneling Microscope (STM)
SPM Systems
Piezoelectric Scanner
General Overview
An extremely fine conducting probe is heldabout an atom’s diameter from the sample.
Electrons tunnel between the surface and the tip,producing an electrical signal.
While it slowly scans across the surface,the tip is raised and lowered in order to keepthe signal constant and maintain the distance.
This enables it to follow even the smallestdetails of the surface it is scanning.
The Tip
As we will see later, is very important that thetip of the probe be a single atom.
Tungsten is commonly used because you can useElectro-chemical etching techniques to createvery sharp tips like the one above.
Quantum Tunneling
The second tip shown above is recessed by about two atoms and thus carries about a million times less current. That is why we want such a fine tip. If we can get a single atom at the tip, the vast majority of the current will run through it and thus give us atomic resolution.
Note
• A STM does not measure nuclear position directly.
• Rather it measures the electron density clouds on the
surface of the sample.
• In some cases, the electron clouds represent the atom
locations pretty well, but not always.
Converse Piezoelectricity
Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress.When you apply an electric field to a piezoelectric crystal, the crystal distorts. This is known as converse piezoelectricity. The distortions of a piezo is usually on the order of micrometers, which is in the scale needed to keep the tip of the STM a couple Angstroms from the surface.
The tip
PizosElectric Field
Scanning Modes
STM Constant Current Mode
STM Constant Height Mode
System Components
Mechanical Parts
Electronics Parts
Computer + software
Needle replacementNeedle type
Platinum-iridium (PtIr)Tungsten tips Gold
Needle preparationElectrochemical etchingMechanical shearing
System Software Execution
Sample preparation
ZnO Nanoparticles around 6.5-8nm
Gold Nano crystals 6-14nm
Gold N
ano crystals 6-14nm
Gold Nano crystals 6-14nm
Calibration
Etching of atoms and molecules from the surface of gold (100x100nm) by our STM system
(a step for Nanorobotics)
Atomic resolution of graphite
4 ×4 × 0.2 nm
Atomic resolution of graphite
Advantages of Scanning Probe Microscopy
• The resolution of the microscopes • Create small structures nanolithography • Do not require a partial vacuum
Disadvantages of Scanning Probe Microscopy• The detailed shape of the scanning tip• Slower in acquiring images• The maximum image size
References
1. Pooria Gill, Bijan Ranjbar, Reza Saber. Scanning Tunneling Microscopy of Cauliflower-like DNA Nanostructures Synthesized by Loop-mediated Isothermal Amplification. IET Nanobiotechnology 2011; 5 (1), 8-13.
2. Reza Saber, Saeed Sarkar, Pooria Gill, Behzad Nazari, Faramarz Faridani. High Resolution Imaging of IgG and IgM Molecules by Scanning Tunneling Microscopy in Air Condition. Scientia Iranica (Transaction F: Nanotechnology) 2011; 18 (6), 1643–1646.
3. M.Q. Li. Scanning probemicroscopy (STM=AFM) and applications in biology, Appl. Phys. A 68, 255–258 (1999).
4. Errez Shapir et al., High-Resolution STM Imaging of Novel Single G4-DNA Molecules, J. Phys. Chem. B, Vol. 112, No. 31, 2008.
5. D. P. ALLISON. Immobilization of DNA for scanning probe microscopy, Proc. Nadl. Acad. Sci. USA, Vol. 89, pp. 10129-10133, November 1992.
6. Hiroyuki Tanaka. Visualization of the Detailed Structure of Plasmid DNA, J. Phys. Chem. B 16788 2008, 112, 16788–16792.
7. Hiroyuki Tanaka. High-resolution scanning tunneling microscopy imaging of DNA molecules on Cu(111) surfaces, Surface Science 432 (1999) L611–L616.
8. Handbook of microscopy for nanotechnology / edited by Nan Yao. Zhong Lin Wang. 2005 Kluwer Academic Publishers.
9. Scanning probe microscopes : applications in science and technology / K.S. Birdi. 2003 by CRC Press LLC.
10. SCANNING PROBE MICROSCOPY, 2007 Springer Science+Business Media, LLC.
Thanks for your Attentions
Mazandaran University of Medical Sciences and Health Care
Sari, I.R. Iran
www.mazums.ac.ir
STM: Applications in Biomedicine
Pooria Gill
PhD Of Nanobiotechnology
Faculty of Medicine
Mazandaran University of medical sciences
In The Name of Allah
Nanoscopy of Nanostructured Biomolecules
Structural Analyses
Interactiomics
Partial Sequencing
Immobilization Characterization
Peptide Characteristics
Microbial Characteristics
Viral Characteristics
…
Single strand of calf thymus DNA deposited along a surface step of HOPG. (50 x 50 nm, constant current mode, current 0.1 nA, bias voltage 500 mV.)
Methods In Molecular Biology, Vol 22. Microscopy, Opt/cat Spectroscopy, and Macmscop/c Technrqoes Edlted by: C Jones, I3 Mulloy, and A H. Thomas Copynght 01994 Humana Press Inc., Totowa, NJ.
STM of λ-DNA (GeneRuler DNA) on HOPG
P. Gill, B. Ranjbar, R. Saber. IET Nanobiotechnol., 2011, Vol. 5, Iss. 1, pp. 8–13.
3D image of a single antibody (IgG) molecule after the filtering and coloring process, which shows orientation of this molecule after physical adsorption on the rigid surface from the hinge region imaged by NAMA-STM
R. Saber, S. Sarkar, P. Gill, B. Nazari, F. Faridani. Scientia Iranica F (2011) 18 (6), 1643–1646.
3D image of a single antibody (IgM) molecule, imaged by NAMA-STM. (b) Standard configuration of human immunoglobulin M with pentameric domains
R. Saber, S. Sarkar, P. Gill, B. Nazari, F. Faridani. Scientia Iranica F (2011) 18 (6), 1643–1646.
STM
com
pa
rison
of
passiv
e
an
tibo
dy
ad
sorp
tion
an
d
bio
tinyla
ted
an
tibo
dy
linkag
e to
stre
pt
avid
in
on
m
icro
tite
r w
ells
STM
im
ages
of
antife
rritin
antib
odie
s passiv
ely
adso
rbed to
a
micro
well
surfa
ce
STM
im
ag
es o
f b
iotin
yla
ted
antife
rritin
an
tibo
die
s im
mob
ilized
to a
stre
pt
avid
in
coate
d
micro
well
surfa
ce
Davies et al., Journal of Immunological Methods, 167 (1994) 263-269.
Individual Peptide Structures Visible by STM
Reconstructed surface topography of coated T4 polybead capsomeres; (a) the TEM and (b) STM representations. The slight variation in the representation may be due to the overlying carbon film, which is observed by STM but not by TEM. Height range is 2.3 nm. (Reprinted with permission from Stemmer et al., 1989.)
M. FIRTEL and T. J. BEVERIDGE. Scanning Probe Microscopy in Microbiology. Micron, Vol. 26, No. 4, pp. 347-362, 1995.
Reconstructed surface topography of coated T4 polybead capsomeres; (a) the TEM and (b) STM representations. The slight variation in the representation may be due to the overlying carbon film, which is observed by STM but not by TEM. Height range is 2.3 nm. (Reprinted with permission from Stemmer et al., 1989.)
M. FIRTEL and T. J. BEVERIDGE. Scanning Probe Microscopy in Microbiology. Micron, Vol. 26, No. 4, pp. 347-362, 1995.
STM image of coated (a) sheath and (b) hoops from M. hungatei. Bars: x, y = 100 nm; z = 8 nm.
M. FIRTEL and T. J. BEVERIDGE. Scanning Probe Microscopy in Microbiology. Micron, Vol. 26, No. 4, pp. 347-362, 1995.
Thanks for your Attentions
Mazandaran University of Medical Sciences and Health Care
Sari, I.R. Iran
www.mazums.ac.ir