KIKUCHI-LIKE EFFECTS IN X-RAY PHOTOELECTRON DIFFRACTION FROM THE CAF2(111) SURFACE

At relatively high electron energies, the patterns observed in X-ray p hotoelectron diffraction (XPED) for light solids are dominated by ''ba nds'' corresponding to the main crystallographic planes in the crystal . These bands can be termed ''Kikuchi-like'' and occur for the same re asons that give rise to the well-known Kikuchi bands in electron diffr action. In the present work we examine in detail the fine mesh XPED pa ttern from the CaF2(111) surface by using the single scattering cluste r-spherical wave theory (SSC-SW). We find that the theory reproduces w ell the main Kikuchi-like characteristics of the observed pattern and is sensitive to the size of the diffracting domains. (C) 1997 Elsevier Science B.V.