Vibronic tunneling mechanism

Ross and co-workers have presented a mechanism of internal conversion for which Teller crossings 166 are not necessary. Following a line of reasoning similar to that of Robinson,5 they suggested that internal conversion can occur from any vibronic level, if from that level tunneling through the barrier can occur. 

Abstract Contribution of the Jahn-Teller system to the elastic moduli and ultrasonic wave attenuation of the diluted crystals is discussed in the frames of phenomenological approach and on the basis of quantum-mechanical theory. Both, resonant and relaxation processes are considered. The procedure of distinguishing the nature of the anomalies (either resonant or relaxation) in the elastic moduli and attenuation of ultrasound as well as generalized method for reconstruction of the relaxation time temperature dependence are described in detail. Particular attention is paid to the physical parameters of the Jahn-Teller complex that could be determined using the ultrasonic technique, namely, the potential barrier, the type of the vibronic modes and their frequency, the tunnelling splitting, the deformation potential and the energy of inevitable strain. The experimental results obtained in some zinc-blende crystals doped with 3d ions are presented. 

A quantum-mechanical tunnelling model of non-radiative decay 492 has been proposed. Several papers have been concerned with the choice of basis set for treatments of non-radiative decay,498 and it has been shown in the paper of Sharf that higher-order vibronic terms are comparable in magnitude with those of the first-order term. It is thus not sufficient to make the usual assumption that interactions describing non-radiative decay are independent or linearly dependent on nuclear co-ordinates. The other papers reinforce this point, and... 

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