Oxygen on Pt(110): Thermal enhancement of electron stimulated desorption

Abstract

Adsorption of oxygen on Pt(110) at room temperature occurs in two stages, a rapid adsorption to about half the saturation coverage followed by a much slower adsorption. Electron stimulated desorption (ESD) produces a small yield of O + ions. If the saturated surface is heated above about 600 K, the ESD yield of O + can increase by as much as twenty times. The high yield condition produced by heating is then stable at lower temperatures. Complete desorption occurs on heating above ∼ 900 K. If the exposure at room temperature is arrested after the initial rapid adsorption, the transition above 600 K is not observed. However, adsorption above 600 K on the clean surface gives directly the high O + yielding state. The observations relate to some activated surface re-arrangement but more studies are required to verify whether or not the platinum atoms are directly involved.