Interaction mechanisms in the Bi3+ -Eu3+ energy transfer in germanate glass at low temperature

The mechanisms of low temperature (T = 4 K) energy transfer between Bi3+ and Eu3+ in germanate glass have been studied under pulsed nitrogen laser excitation by selecting the emission from a subset of ions in the 3P0 → 1S0 band which is broadened by inhomogeneity in the glass. The decay curves of the emission from the Bi3+ 3P0 state were obtained for various concentrations of acceptor ions Eu3+. There is no indication of diffusion of the excitation energy within the donor system. The experimental curves were fitted to Inokuti and Hirayama's equation. The best fit was obtained with a dipole-dipole interaction for the 0.8 % Bi 3+ + 0.7 % Eu3+ doped glass and with a quadrupole-dipole interaction for the 0.8 % Bi3+ + 5 % Eu3+ doped glass.