Back transfer in the S-4(3/2) state of Cs2NaErxY1-xCl6 extension of the shell model

摘要

The S-4(3/2) state of Er3+ in Cs2NaErxY1-xCl6 undergoes a cross relaxation above 100 K which involves a transition from the S-4(3/2) to the I-4(9/2) and I-4(3/2) states at the donor (D) and the excitation of the acceptor (A) to the I-4(13/2), I-4(9/2) states. Analysis of experimental decay curves from the S-4(3/2) State for x = 0.001 - 1 using the standard shell model for energy transfer in the elpasolite lattice has not been successful. In this system the energies of the crystal held levels means that the rate of back transfer from the acceptor to the donor is comparable with or greater than the cross relaxation rate, and therefore must be included explicitly. The effect that inclusion of the back transfer terms has on the decay of the S-4(3/2) State is examined numerically. We have simulated decay curves for the S-4(3/2) State within the shell model with inclusion of the back transfer terms. These simulated curves are in good agreement with the experimental decay curves. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 8]