Subthreshold radiation-induced processes in the bulk and on surfaces and interfaces of solids

Abstract

A review is given on the processes induced under irradiation by electronic encounters and by elastic encounters below the knock-on threshold. It is pointed out that electronic encounters cause bond scission that results in defect formation and sputtering in a variety of materials. The conditions for generation of permanent radiation-induced process as a consequence of electronic encounters are critically examined. Two critical issues are localization of electronic excitation energy and energetics. Self-trapping of excitons is one way of localization; otherwise defects are involved in localization and therefore in radiation-induced processes (RIP) by electronic excitation. Arguments on energetics indicate presence of linear and nonlinear electronic processes with respect to the density of excitation. The registration of energetic heavy-ion tracks is explained in terms of nonlinear electronic processes. The difference in the processes in the bulk, on surfaces and at interfaces is critically discussed. The possible contribution of the subthreshold elastic encounters to thermodynamically driven interface reaction is also discussed.