PHYS: Electron holography better than STM

Max More (
Wed, 17 Dec 1997 08:38:47 -0800

The American Institute of Physics Bulletin of Physics News
Number 351 December 16, 1997 by Phillip F. Schewe and Ben

ELECTRON HOLOGRAPHY can supply an atomic-resolution
image both of the atoms in a surface and (unlike STM) some of the
atoms in layers underneath. Physicists at the University of
Erlangen-Nurnberg in Germany have converted a popular surface-
imaging technique---low energy electron diffraction (LEED)--- into
a form of holography. In conventional holography, part of a laser
beam (the object beam) is scattered from an object and part (the
reference beam) left unscattered. The scattered and unscattered
waves meet in a piece of film where they inscribe an interference
pattern which, when reconstituted, renders a three-dimensional
image of the object. In the Erlangen experiment all of this happens
on a nanoscopic level, with electron waves instead of light waves.
When an electron beam strikes a surface, any prominent atom can
be thought of as a beam splitter creating a reference electron wave
and---after subsequent scattering by neighboring atoms---an object
wave. From the measured electron diffraction pattern a 3-
dimensional image of the local environment of the beam-splitting
atom can be reconstructed. In this way, the surface structure of the
crystal SiC (a potentially important material for electronics
applications) was determined. (K. Reuter et al., Physical Review
Letters, 15 Dec.; contact Klaus Heinz, kheinz@kgp.physik.uni-, 011-49-913-185-8403; or Ulrich Starke,