No abstract

A theoretical consideration is made of the thermal broadening and shift of the impurity energy levels in crystals doped with TR3+ ions using the Hamiltonian of electron-phonon interaction containing linear terms in the lattice variables. I n the method developed for the calculation of these effects the real phonon density distribution is used for the host crystal. The information about this distribution is obtained from the spectrum of vibrational satellites of zero-phonon lines. The calculations are carried out for the thermal broadening and the shift of some lines in the 4F3/2 + 411112 luminescence band of the Nd3+ ion in an YAlO, host crystal.l) The same model was used in [7] for calculations of the parameters of the theory [l] for the R-lines of ruby.

Yu. E. PERLIX et al. : Eonradiative Jhltiphonon Relaxation in Y3A1,0,,: Nd3+ phys. stat. sol. (b) 92, 403 (1979) Subject classification: 13.4 and 20.3; 6; 22.8 VYLEGZHANIN (b) Analytical expressions are derived for the multiphonon decay rate of an isolated impurity level, when interaction with low-frequency phonons appears as small perturbation. Both, the interaction with high-frequency optical phonons and the contribution of Jahn-Teller vibrations are taken into account in the framework of first cumulant approximation. In the temperature range 0 to 700 K the transition probability 4111jr -* * l y p of the states of Nd3+ ions in Y3A41j0,3 crystals are ralculated numerically. The results are in agreement with data obtained from laser generation kinetics. IIOJlyYeHa @OpMyJIa HJIR

The method of selective spectroscopy is used for analysing the kinetics of processes occuring under the conditions of excitation‐energy exchange among activator centres of Pr3+‐doped crystalline media, and typical peculiarities in the behaviour of ordered multicentred and disordered crystals are revealed. The approach to phonon density determination of multicentred and disordered crystals by Raman spectra data is suggested.