Cooperative quenching: experiment, theory and Monte-Carlo computer simulation

An analytical expression and results of Monte-Carlo computer simulations are proposed for the kinetics of cooperative static quenching decay in crystals with arbitrary acceptor concentration and arbitrary multipolarity of interaction process S = 6, 8, 10, which at a long decay time can be approximated by the nonexponential law I(t)exp[-(wt)(k)], where k = 0.41, 0.3, 0.25 for multipolarities S = 6, 8 10, respectively. The phenomenon of cooperative energy transfer from single Nd3+, Tm3+ or Ho3+ ion simultaneously to the pair of Ce3+ ions and from single Er3+ ion to three Ce3+ ions with, respectively, two and three times smaller transition energy each in highly concentrated La1-xCexF3 crystals is presented. The influence of overlap integral (between donor ion and cooperative pair and triple Ce3+ acceptor) and electronic matrix elements of donor transitions on the cooperative energy transfer rate for a set of donor ions is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.