STUDY OF SURFACE PROPERTIES OF ATOMICALLYCLEAN METALS AND SEMICONDUCTORS. PART 1. STUDY OF CDS SURFACES BY LEED. PART 2. COMBINED LEED AND MASS SPECTROMETER MEASUREMENTS FOR ADSORPTION AND CATALYSIS.

The 0001 MATTE natural growth surface of a vapor grown CdS crystal which had not been polished or etched was studied. It was not possible to obtain a clean surface by heating alone because of contamination from the bulk. Ion bombardment and annealing produced 1014 planes as was found on previously studied crystals. Oxygen adsorption studies of the 0001 MATTE surface, after using Ga-In eutectic to make contact to the crystal mount, were made. However, the magnitude of these changes was not reproducible. Oxygen adsorption studies of the 0001 SPECULAR surface with no Ga-In contact revealed that photoassisted adsorption occurred. The change in surface potential was approximately directly proportional to the change in oxygen coverage as estimated from decreases in diffraction pattern intensities. This indicates that the oxygen forms negative surface states. The system involving a combination of LEED and quadrupole mass spectrometer was assembled and tested with self oxidation of CO on a 100 nickel crystal surface. The diagonal mark 1 is here used to indicate the rotation-inversion axis.