INTERACTION OF CO AND O-2 WITH PT STUDIED BY FIELD-ION APPEARANCE ENERGY SPECTROSCOPY

Using field ion appearance energy spectroscopy we have examined the in teraction of CO and O-2 with stepped platinum surfaces in the presence of electrostatic fields ranging between 10 and 20 V/nm. Mass-to-charg e resolved retarding potential analyses have been carried out for sing le sites of [001] and [111]-oriented Pt field emitter exposed to a con tinuous flow of CO and O-2. Applying a thermionic cycle, binding energ ies of molecularly adsorbed CO and O-2 were derived from the appearanc e energies of field desorbed CO+ and O-2(+). The data reveal an effect of the high field on the molecule-surface interaction, which is most pronounced for CO/Pt(111) steps. Implications for FIM studies of catal ytic CO and H-2 oxidation reactions are discussed.