Evidence of higher-order mechanisms than dipole-dipole interaction in Tm3+→Tm3+ energy transfer in fluoroindogallate glasses -: art. no. 094204

The energy migration H-3(4), H-3(6)-->H-4, H-3(6) and the cross relaxation H-3(4), H-3(6)-->F-3(4), F-3(4) between Tm3+ ions in fluoroindogalatte glasses are studied by means of Dexter, Kushida, and Yokota-Tanimoto models. Dexter and Kushida formulations are applied to calculate the energy-transfer microparameters for dipole-dipole, dipole-quadrupole, and quadrupole-quadrupole interactions. A Yokota-Tanimoto treatment for dipole-dipole interactions and a more general expression proposed by Martin et al. [J. Chem. Phys. 111, 1191 (1999)] which includes high order interactions in the donor-acceptor energy transfer, are also used to fit the decay curves of the H-3(4) level. The obtained results show that the energy transfer rate by dipole-dipole interaction is lower than that by the high-order approximations even for a sample with 1 mol % of Tm3+. Yokota-Tanimoto and Martin expressions, applied to the decay curves of the H-3(4) level, do not yield meaningful values for the energy-transfer microparameters. This is probably because the studied system presents more than one multipole coupling, which is not considered by the model.