X-Ray Photoelectron Spectroscopic Studies of Cadmium- and Silver-Oxygen Surfaces

The surface chemistry of the Cd- and Ag-oxygen systems has been studied by X-ray photoelectron spectroscopy (XPS or ESCA) using both temperature changes and ion bombardment techniques as methods of inducing structural changes. For the Cd system, the O 1s binding energies for CdO, Cd(OH)₂, CdCO₃, and CdO₂ have been characterized and have been used to follow the decomposition of these species as a function of temperature. For oxygen-exposed evaporated films of Cd, two distinct oxygen phases were noted with one being specifically identified as CdO. For the Ag system, the O 1s binding energies of AgO, Ag₂O, and Ag₂CO₃ were reported. On the oxides prepared In air, a significant carbonate contaminant was noted which complicated the interpretation of the O 1s spectra. For oxygen-exposed evaporated Ag films, no oxide phases were noted even at high oxygen exposures although a broad, structureless background, probably corresponding to absorbed oxygen, was observed.