The nanosecond and microsecond fluorescence kinetics decay from 3F3, 3H4, 3H5, 3F4 multiplets of Tm3+ and 5S2,5F5,5I5,5I6,5I7 multiplets of Ho3+ ions in Y3Al5O12, Lu3Al5O12, and LiYF4 crystals with low dopant concentration was directly measured. On the basis of these measurements the multiphonon relaxation (MPR) rates for three, four, and five phonon transitions were determined.
The theoretical depedence of multiphonon relaxation rates versus rare-earth ionic radius was derived using the non-linear (NL) theory of multiphonon relaxation. A good qualitative agreement of this dependence with new and earlier measured MPR rates in rare-earth ions in the row from Tm3+ to Pr3+ in YAG, YLF, and LaF3 crystals was obtained. The regularities of multiphonon relaxation rates on the number of phonons n, 4f-4f electronic transitions selection rules, and crystal type are also considered.
© 1996 Optical Society of AmericaPDF Article