Number 351 (Story #1), December 16, 1997 by Phillip F. Schewe and Ben Stein
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@fkp.physik.uni- erlangen.de, 011-49-913-185-8403; or Ulrich Starke, ustarke@fkp.physik.uni-erlangen.de)
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