INVERTED PHOTOELECTRON DIFFRACTION - A NEW TECHNIQUE FOR SURFACE-STRUCTURE DETERMINATION

A reversal of the conventional X-ray photoelectron diffraction (XPD) experiment is described in which an incident electron beam is diffracted to reach different sites within a crystal with differing relative probabilities, which are expected to mirror those for the escape of photoelectrons from the same sites in the XPD experiment. The diffracted-electron flux arriving at each site is monitored by measuring the intensity of the characteristic X-ray emission following core ionisation by the incident electrons. This new approach potentially offers advantages over XPD in respect of minimum sample size and angular resolution in relation to equipment costs. Preliminary results from a GaAs crystal confirm that a clear correlation exists between results from the new technique and from XPD.