Scanning Tunneling Microscope(STM) & Atomic Force Microscope (AFM)

STM & AFM

Scanning Tunneling Microscope (STM)

These are devices 2D & 3D Surface analysis of Materials at micrometer resolution. Scanning Tunneling Microscopic is based upon the tunneling theory i.e. an electron may tunnel (or jump) through a barrier when the barrier is thin enough. So produces

an elctric current at the surface. If we can use a microtip probe. we can monitor the tunneling current profile in a 2D surface. Which will give a 2D picture of the atomic structure. But the necessary condition for the probe to get image at atomic scale is that the probe shou

ld be moved at such resolution.

Here comes the role of Piezo transducers, we have used steppers Servos for precison positioning but when the precison we need is of micrometer level we have the only option Piezo Transducers.

As we know Piezo materials produce Structurals change (expand or compress) in the axis of applied field. So for an X Y scan we can use two piezo plates or a single block and the probe at a corner. Commonly we use two piezo plates at two sides.

Some more PIC of AFM

References:

http://www.siint.com/en/products/spm/tec_descriptions/descriptions2_e.html

http://www.ieap.uni-kiel.de/surface/ag-kipp/stm/stm.htm

http://www.quasi.iastate.edu/hot.html

http://sxm4.uni-muenster.de/stm-en/STMElectronics.html (Making DIY STM)

http://www.stm.phas.ubc.ca/Science/Introduction-to-STM.html

http://www.foresight.org/UTF/Unbound_LBW/chapt_4.html

http://www.tutorialsweb.com/nanotech/page-6.htm

http://www.phys.ttu.edu/~tlmde/thesis/DESIGN_AND_CONSTRUCTION.html

http://www.physics.leidenuniv.nl/sections/cm/ip/Onderwijs/Scanning-Probe-Microscopy/Chapters/CHEN%20Chapter%209%20Piezoelectric%20scanner%20213-235.pdf

http://www.nanodic.com/Nanocharacterization/Atomic_Force_Microscopy.htm

http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_205%3A_Larsen/ChemWiki_Module_Topics/How_an_FTIR_Spectrometer_Operates