RADIATION-STIMULATED DIFFUSION IN SOLIDS

Irradiation of solids produces a microscopic nonequilibrium state in w hich the vibrational energy distribution function of the atoms deviate s from the thermodynamically equilibrium function. Expressions are obt ained for the nonequilibrium distribution function and for the frequen cies of activational transitions of atoms out of a potential well. It is shown that the radiation stimulation of diffusion processes involve s a deviation of the temperature dependences of the frequencies of tra nsitions of the atoms out of positions of equilibrium from the Arrheni us law. Under subthreshold irradiation conditions the rate of diffusio n processes is higher for atoms whose vibrations thermalize over long times and depends linearly on the irradiation intensity. Under above-t hreshold irradiation conditions the characteristics of cascade regions in solids - their sizes and the vibrational excitation energy of the atoms - can be determined by comparing the computed and experimental t emperature dependences of the diffusion coefficient. (C) 1998 American Institute of Physics. [S1063-7842(98)01108-8].