Photoelectron emission from mica by light with energy lower thanphotothreshold

摘要

In order to determine the mechanism of photoelectron emission fromnthe cleaved mica surface in more detail, the influence of the luminousnintensity on the emission and the photothreshold was studiednexperimentally. The photoelectron emission from the mica surface isnfound to be considerably influenced by temperature and luminousnintensity, and this phenomenon can mostly by attributed to the fact thatnthe photothreshold for emission varies with intensity as well asntemperature. The shift of the photothreshold with the temperature isncomparatively large (0.63 eV between 20° C and -100° C), andntherefore it is suggested that thermal excitation contributes to thenprocess of photoelectron emission. The more intensive illuminationncauses the photothreshold to shift to the shallower levels in thensurface states, with the result that the electrons trapped in the statesnare accumulatively excited and are finally emitted even undernillumination with energy lower than the photothreshold