Transcript STM Workshop 12-9-1393

In The Name of Allah
Scanning Tunneling Microscope
Pooria Gill
Ph.D. of Nanobiotechnology
Faculty of Medicine
Mazandaran University of Medical sciences
[email protected]
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
Scanning Tunneling Microscope (STM)
The STM is an electron microscope that
uses a single atom tip to attain atomic resolution.
SPM Systems
Piezoelectric Scanner
General Overview
An extremely fine conducting probe is held
about 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 keep
the signal constant and maintain the distance.
This enables it to follow even the smallest
details of the surface it is scanning.
The Tip
As we will see later, is very important that the
tip of the probe be a single atom.
Tungsten is commonly used because you can use
Electro-chemical etching techniques to create
very sharp tips like the one above.
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.
Electric Field
Pizos
The tip
Scanning Modes
STM Constant Current Mode


STM Constant Height Mode

System Components 
Mechanical Parts
Electronics Parts
Computer + software
Needle replacement
Needle type
Platinum-iridium (PtIr)
Tungsten tips
Gold
Needle preparation
Electrochemical etching
Mechanical shearing
System Software Execution
Sample preparation

Gold Nano crystals 6-14nm
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
STM: Applications in
Biomedicine
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 comparison of passive antibody adsorption and
biotinylated antibody linkage to streptavidin on microtiter
wells
STM images of antiferritin antibodies passively
adsorbed to a microwell surface
STM images of biotinylated antiferritin antibodies
immobilized to a streptavidin coated microwell
surface
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.
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