ANGLE-RESOLVED FED AND AED CALCULATIONS FOR DIFFERENT STRUCTURES OF THE DIAMOND C(111) SURFACE

Angle-resolved (AR) photoelectron diffraction (PED) spectra for electr ons excited from the C 1s core state and angle-resolved KVV Auger elec tron diffraction (AED) spectra are calculated for the Pandey and the T sai stucture models of diamond C(111) which extend previous investigat ions of the ideal structure. It is shown how to decide on the structur e model by comparing PE spectra for different directions and by compar ing PED and AED spectra. Calculations have been performed by evaluatin g the scattering path operator for a finite cluster in a curved-wave a pproximation. The different matrix elements for the photoelectron exci tation and for the Auger process, respectively, are included. It is sh own that the PED intensities are very sensitive to the surface reconst ruction for polar angles in the range of 80 degrees. In the AED intens ities, polar scans in the plane perpendicular to the chain direction c an be considered. (C) 1998 Elsevier Science B.V. All rights reserved.