Luminescence of K1–xRbx CaF3 upon the outermost 3p K+ and 4p Rb+ core ionization

Abstract

AbstractThe luminescence and reflection spectra of K1–x Rbx CaF3 crystals have been studied using synchrotron radiation. Luminescence of self‐trapped exciton and core‐valence luminescence are revealed for KCaF3 crystals in UV and VUV spectral range, respectively. The core‐valence VUV luminescence of KCaF3 appears after 3p K+ core ionization and originates from the radiative recombination of 3p K2+ core holes with 2p F– valence electrons. The fast UV luminescence of K1–x Rbx CaF3 crystals has been attributed to the radiative recombination of the holes in 4p Rb2+ impurity core states with 2p F– valence electrons. The impurity core‐valence luminescence of K1–x Rbx CaF3 reveals the excitation threshold corresponding to the ionization of impurity 4p Rb+ core states. Efficient excitation of 4p Rb+ related luminescence of K1–x Rbx CaF3 within the energy range of 3p K+ core ionization is considered as an evidence for the hole migration from the host 3p K+ core band to the impurity 4p Rb+ core states. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)