Two mechanisms of 1D2 fluorescence quenching of Pr3+‐doped Y2SiO5 crystal

In Y2SiO5:Pr3+ crystals (0.1 at%, 0.3 at%, 0.6 at% , and 1.8 at% Pr3+) characterized by the existence of two types of Pr3+ optical centers, the energy transfer has been investigated using time‐resolved site‐selective spectroscopy techniques. The results obtained show that at certain conditions there are two different mechanisms of fluorescence quenching of the excited 1D2 states of Pr3+ ions. At 0.3 at% Pr3+ and under the excitation of 1D2 states as the result of 3P0 → 1D2 nonradiative relaxation, the phonon‐assisted energy transfer from 1D2 states of the I‐type Pr3+ ions to the II‐type ones has been found. The nonexponential part of donor fluorescence decay was described by the law t0.5. and the transfer efficiency exhibits a strong temperature dependence in the range of 1.5–80 K. At the direct selective excitation of the 1D2 states of one type Pr3+ optical centers it was possible to observe only their own fluorescence which quenched at a concentration above 0.6 at% Pr3+. The donor fluorescence decay was not fit by the law t0.5 and the quenching efficiency was characterized by the square‐loaw dependence on the concentration and a very poor dependency on the temperature. The analysis of some models allows us to assume, that in this case, the cooperative quenching of the 1D2 states of both type Pr3+ optical centers can take place. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)