Optical and photoelectron spectroscopy studies of KPb2Cl5 and RbPb2Cl5 laser crystals

Abstract

The paper presents the results of experimental study of electronic structure of RbPb2Cl5 and KPb2Cl5 laser crystals performed by the optical and photoelectron spectroscopy methods. On the basis of the optical absorption and low-temperature reflection spectra of these crystals we have determined the energy positions of the edges of the low-energy tail of the host absorption, the positions of the first excitonic absorption peaks, and exciton binding energies. The bandgap widths of these crystals at 8K were estimated as Eg=4.83 and 4.79eV, respectively. Qualitative and quantitative analysis of RbPb2Cl5 and KPb2Cl5 crystals were made on the basis of the core states photoelectron spectra. The elemental composition of the (001) surfaces of the crystals, the chemical state of the host atoms, the electronic structure of the valence band of the crystals were discussed on the basis on the spectroscopic data.