Can we see atoms ?

Can we see atoms ?
Atoms are so smaller that we can't see with our eyes or microscope.However,in 1981 Gerd Binning and Heinrich Roher invented Scanning Tunneling Microscope (Nobel Prize in Physics in 1986).With this STM we can get good resolution pictures i.e..0.1 n.m lateral resolution,0.01 n.m depth resolution.With this resolution individual atoms within the materials are routinely imaged

    STM image of gold surface here we can see individual atoms of gold

    Photos courtesy wikipedia

    Silicon purple sphere is silicon atom

    cyclopentene molecules on silicon 3.2x3.4 n.m

Scanning Tunneling Microscope

A scanning tunneling microscope (STM) is an instrument for imaging surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer (at IBM Zürich), the Nobel Prize in Physics in 1986

The STM consists of the following

A very small, sharp tip that conducts electricity (probe )

A rapid piezoelectric scanning device to which the tip is mounted

Electronic components to supply current to the tip, control the scanner and accept the signals from the motion sensor

Computer to control the system and do data analysis (data collection, processing, display)

The STM works like this:

A current is supplied to the tip (probe) while the scanner rapidly moves the tip across the surface of a conducting sample.

When the tip encounters an atom, the flow of electrons between the atom and the tip changes.

The computer registers the change in current with the x,y-position of the atom.

The scanner continues to position the tip over each x,y-point on the sample surface, registering a current for each point.

The computer collects the data and plots a map of current over the surface that corresponds to a map of the atomic positions

    Heinrich Roher

.    Gerd Binning 

   Scanning Tunneling Microscope(STM)

    STM (Scanning Tunneling Microscope) HEAD