VUV PHOTOELECTRON DYNAMICS IN PURE CESIUM HALIDE AND IMPURITY (Tl AND Na) DOPED CsI; ABSOLUTE PHOTOEMISSION TOTAL YIELD, AUGER FREE LUMINESCENCE, AND STE LUMINESCENCE

Abstract

Absolute photoemission total yield (APTY) spectra and VUV-excited luminescence in cesium halides of CsCl, CsBr, and CsI, as well as in Tl-doped and Na-doped cesium iodide, were studied at several temperatures from 400 K to 80 K in the VUV region (5–30 eV). Although it is common that the intensities of APTY exceed unity in the photon energy region exciting Cs + 5p core electron in all of these halides at room temperature, this is most in the cesium iodides and most less in CsCl. These phenomena are explained in terms of Auger enhancement due to the Auger effect associated with the decay process of the Cs + 5p core hole. From the detailed analysis of temperature dependence of APTY and of Auger free luminescence (AFL) in CsCl and CsBr, a strong complementary relation between APTY and AFL was revealed, and the temperature-dependent energy level diagram of CsBr including the valence band and the Cs + 5p core level was proposed. While in these CsI, APTY indicate as large as 1.5 or more at the high temperature and the decrease of APTY for decreasing temperature can be commonly explained in terms of the complementary relation with photoluminescence.