Luminescence self-quenching in Tm3+: YLF crystals: II. The luminescence decay and macrorates of energy transfer

Microparameters of migration and self-quenching of luminescence from the (³ P ₀, ¹ I ₆) levels of Tm ³⁺ ions are calculated and the luminescence decay from the ³ H ₄, ¹ G ₄, and ¹ _{D 2} levels are analyzed in the concentration series of LiY_1?x Tm_xF₄(x=0.5–10 at. %) crystals upon weak selective excitation. It is shown that the luminescence decay of a thulium ion concentration higher than 0.5 at. % cannot be described by the energy transfer that takes into account only the dipole-dipole interaction. The comparison of experimental kinetic curves with theoretical curves calculated within the framework of the known energy transfer models showed that multipole-multipole interaction is responsible for the self-quenching of the thulium levels. Contributions of higher multipole interactions to the self-quenching are estimated. The decay of luminescence from the ³ H ₄, ¹ G ₄, and ¹ D ₂ levels of Tm³⁺:YLF crystals with different concentrations of thulium ions is described analytically.