Contents
         Contents
   History
   History
   Introduction
   Introduction
   Some Definitions
   Some Definitions
   Basic Principle
   Basic Principle
   Set-Up
   Set-Up
   Applications
   Applications
                       History
                       History
     Developed in the 1981 by 
      Developed in the 1981 by 
      Gerd Binnig and Heinrich 
      Gerd Binnig and Heinrich 
      Rohrer at IBM Zürich .
      Rohrer at IBM Zürich .
     Patented by IBM in 1982.
      Patented by IBM in 1982.
     Won Nobel prize in 1986.
      Won Nobel prize in 1986.
     Achievement of Atomic 
      Achievement of Atomic       silicon surface atoms enlarged 20 
      Resolution                  million times, color-enhanced by 
      Resolution                  computer. 
     Resolution:~0.01 nm.
      Resolution:~0.01 nm.        The world's first images of individual 
                                  surface atoms and the bonds that hold 
                                  them in place were produced by a 
                                  research technique developed by IBM 
                                  -- scanning tunneling microscopy.
             Introduction 
             Introduction 
    Scanning tunneling microscope (STM) is a powerful technique for viewing 
    Scanning tunneling microscope (STM) is a powerful technique for viewing 
    surfaces at the atomic level.
    surfaces at the atomic level.
    STM probes the density of states of a material using tunneling current.
    STM probes the density of states of a material using tunneling current.
    The STM is based on the concept of Quantum Tunneling.
    The STM is based on the concept of Quantum Tunneling.
   General Overview
   General Overview
  1. An extremely fine conducting probe is held
  about an atom’s diameter from the sample.
  2. Electrons tunnel between the surface and the tip,
  producing an electrical signal.
  3. 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.
             Note
              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.