Electronic transitions in surface and near-surface radiation effects

Abstract

Studies of surface effects arising from electron, heavy particle or photon irradiation of dielectric surfaces are increasingly focusing on the electronic interactions by which energy is absorbed, localized, and transformed or transferred prior to the ultimate dissipation of the incident energy — through, for example, ejection of atoms or molecules from the dielectric. Recent experiments in our laboratories illustrate the varied roles played by electronic transitions in determining the flow of electronic energy during the bombardment of dielectric surfaces by photons, electrons and heavy particles. Specific examples include: the effects of surface overlayers and adsorbed hydrogen in retarding substrate desorption; substrate-temperature- and energy-resolved studies of photon-stimulated desorption from alkali halides; and electronic level-hybridization effects in the sputtering of metal oxides by argon ions. These simple model systems are a critical testing ground for studying the mechanisms of surface radiation damage in more complex materials because of the wealth of information available about their electronic and geometric structure, and because the character and modes of formation of their permanent electronic defects are well understood.