1971/11/01 by Marvin J. Weber · 3 citations
Materials Science · Physics and Astronomy · #Glass properties and applications #Lanthanide and Transition Metal Complexes #Quantum optics and atomic interactions
paper · doi:10.1103/physrevb.4.2932
The time dependence of the luminescence decay following pulsed excitation is examined for a system in which excited paramagnetic ions decay by a combination of intrinsic relaxation processes, direct energy transfer to acceptor ions, and energy migration. Three limiting cases are considered: direct energy transfer in the absence of diffusion, rapid diffusion, and diffusion-limited relaxation. Investigations of the transient europium fluorescence from a chromiumdoped europium phosphate glass, where excited Eu3+ ions form the donor system and Cr3+ impurities act as energy acceptors, are reported which illustrate these limiting cases. By varying the temperature and Cr3+ concentration, transient fluorescence behavior characteristic of diffusion-limited relaxation is studied. The data are analyzed to determine the probability for direct Eu3+ \ensuremath→ Cr3+ energy transfer, the critical transfer distance for energy exchange, and the diffusion constant D for energy migration through the europium system. D varies with temperature as levels having greater probabilities for resonant Eu3+-Eu3+ energy transfer become thermally populated. In the diffusion-limited relaxation case the decay rate is predicted to be proportional to D(3)/(4); this (3)/(4) power law is verified.