Ultraviolet photoabsorption measurements in alkali iodide and caesium bromide evaporated films

Ultraviolet–photon absorption constants were measured for thin CsI, KI, RbI, NaI and CsBr evaporated films, in the 140–200 nm spectral range. The constant measured for CsI is consistent with literature data; the absorption data for the other materials are given here for the first time. The absorption lengths for all materials investigated vary between 10 and 40 nm. Post-evaporation thermal treatment of the films, known to enhance the photoemission properties of CsI, NaI and CsBr films, had no effect on their photoabsorption properties.