Extrinsic photoemission and diffusion of ’’free’’ excitons in solid xenon

Abstract

Extrinsic photoemission from pure solid rare gases at energies below the direct photoemission threshold is assigned to the diffusion of ’’free’’ mobile excitons (prior to exciton trapping) to the gold (emitter) substrate followed by exciton-enhanced electron ejection from the electrode. From a semiquantitative study of the extrinsic photoemission yield of solid Xe as a function of the film thickness we get the diffusion length l?300 Å, for exciton migration on the time scale of 10−11–10−12 sec.