Photoemission Studies of Electronic Colour Centres in Additively Coloured KCl and KBr Crystals

✍ Scribed by A. D. Kashkai; A. A. Berezin; A. N. Arseneva-Geil; M. S. Matveev

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 431 KB
• Volume: 54
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/pssb.2220540109

✦ Synopsis

Abstract

The spectral distribution of the optical absorption and the photoemission quantum yield and the energy distribution of the photoelectrons are studied in the range of the photon energies of 2.0 up to 5.5 eV on additively coloured KCl and KBr single crystals with a concentration of F‐centres of 10^17^ up to 10^18^ cm^−3^. Several energy levels in the forbidden band, responsible for the photoemission, are found. The positions of these levels in respect to the vacuum level are 2.8, 2.5, and 2.1 eV for KCl and 2.9, 2.3, and 1.7 eV for KBr. These levels are supposed to correspond to the ground states of F‐, M‐, R‐electronic colour centres. The above energy values are compared with the theoretical values of the ionization potential of F‐, M‐, and R‐centres calculated in the quasimolecular model of F‐aggregate colour centres. The calculated first ionization potentials, as well as the experimental energy values, decrease when the electronic colour centre became more complex. In KBr crystals an additional energy level 1.4eV below the vacuum level is found which probably corresponds to the N‐centre.