Температурная зависимость параметров бесфононных линий в спектрах фторидных соединений уранила

Abstract

Temperature dependence of zero-phonon lines parameters (ZPLP) in electronic-vibration spectra of crystals of a type Me3UO2F5 has been investigated in a range of 4,2-5-40 K. Stokes shift of combining electronic states has been determined as a factor leading to the asymmetrical distorting of ZPLP which can be approximated by lognormal distribution with parameters depending on Huang-Rhys factor and effective temperature. Temperature broadening of ZPLP is mainly due to the change of initial states populations. In turn, ZPLP maximums shift is stipulated by the forbidden nature of the first electronic transitions of complex uranyl compounds and is determined mainly by non-liner character of zero-phonon coupling. The temperature dependence of the total integral intensity of given zero-phonon lines can be described in configuration coordinates model of impurity center with one local oscillation.