INELASTIC ION COLLISIONS INVOLVING METAL-SURFACES EXPOSED TO OXYGEN AND ELECTRON-TRANSFER PROCESSES

The effect of oxygen adsorption on excited-state production in ion-sur face collisions, relevant to the production of scattered and recoiled ions is analysed on the basis of recent studies on the modification of resonant electron capture rates. Experiments on negative ion formatio n show that electron capture is strongly affected by changes in local electronic structure and electrostatic potentials around adsorbate sit es, as this had been discussed in the context of promotion and poisoni ng of reactions at surfaces. A comparative analysis for the case of pr oduction of excited states of inert gas ions and recoiled surface meta l atoms and ions is given and shows that the results of some detailed recent experimental studies can be qualitatively understood in these t erms. (C) 1998 Published by Elsevier Science B.V. All rights reserved.