Escape length of ultraviolet induced photoelectrons in alkali iodide and CsBr evaporated films: Measurements and modeling

The escape length of electrons photoinduced from thin CsI, KI, RbI, NaI, and CsBr evaporated films was measured in the 140–180 nm photon spectral range. Theoretical model predictions of the escape length value are in fair agreement with the experimental results. They vary between 10 and 40 nm, the highest values being for CsI, RbI and CsBr. For CsI, measured and calculated ultraviolet-induced escape length values are consistent with that determined from x-ray photoemission quantum yield data. Post-evaporation annealing of the films had no major impact on the measured electron transport properties.