The first images of atoms were achieved in the
1950’s by E. Mueller’s remarkable invention called
a field-ion microscope (FIM). While limited to geometries possessing
high radii of curvature, the FIM is still a useful tool for
studying the properties and arrangements of atoms on sharp tips.
We have used the FIM to study the position of atoms on the surface
of nanometer-size clusters that are supported on electrochemically
etched tips.
Elton Graugnard working on the Field-ion
microscope chamber
A closely related technique is field emission
microscopy. In a field emission experiment, a high electric
field applied to a sharp metal tip distorts the surface
potential barrier and allows electrons to quantum mechanically
tunnel from the metal tip into the vacuum. A simple explanation
of this quantum tunneling effect is given below.
