Scanning Tunneling Microscopy lect-1

 Scanning Tunneling in the Microscope (STM)

in the STM is an electron in the microscope that
uses a in the single atom tip to in the attain atomic resolution.

History

in the scanning tunneling in the microscope was developed at IBM in the Zürich in the 1981 by Gerd Binning and in the Heinrich Rohrer who shared in the Nobel Prize for in the physics in 1986 because of in the microscope.

General Overview

  • An extremely fine in the conducting in the probe is held
  •  in the about an atom’s in the diameter from the sample.
  •  in the in the Electrons tunnel between the surface and the tip,
  •  in the producing an in the electrical signal.
  • vWhile it slowly scans in the across the surface,
  •  in the the tip is  raised in the and lowered in order to keep
  • the signal in the constant and maintain the distance.
  •  in the enables it  to follow in the even the smallest
  • details in the of the surface it  is scanning.

The Tip

As we will see in the later, is very important gh in the tip of the probe be a single in the atom.
Tungsten is in the commonly in the used because you can in the useElectro-chemical etching in the techniques to create very sharp in the tips like the one above.
 
Quantum Tunneling

Classically, in the when an object hits a in the potential that it doesn’t have in the enough energy in the pass, it will never go though that in the potential wall, it always bounces in the back.
in the English, if you throw in the a ball at a wall, it will bounce back in the you.
Now looking in the more in the depth at the case of tunneling in the from one metal to another. EF represents in the the Fermi energy. Creating a in the voltage drop in the between the two metals allows current.
in the Through a barrier, in the quantum mechanics in the predicts that the wave function in the dies off exponentially:

in the Where f(V) is the Fermi function, which in the contains a weighted in the joint local density of states. This a in the material property obtained by in the measurements.
in the Plugging in the typical in the values for m, d, and phi (where phi is the average in the work in the function of the tip and the sample), when in the d changes by 1 Å, the current in the in the changes in the by a factor of about 10!

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