Excitonic ionizations of the electron centres in caesium iodide crystal and exoemission of electrons

In the wide-band-gap alkali halide crystals recombination of defects may result in formation of the excitons, which can ionize an electron F-centre; thus the phenomenon of exoelectron emission takes place. According to this excitonic model, the energy spectrum and mean energy of CsI exoelectrons were attained. The results of theoretical evaluation are compared with experimental and the reasons suggested for the explanation of the observed difference are discussed. The conclusion based on the peculiarities of exoemission from CsI and CsBr crystals, was done.