Excited state relaxation and energy transfer between Tb³⁺ → Nd³⁺ and Tb³⁺ → Ho³⁺ in POCl₃:SnCl₄

Abstract

Excited state relaxation in Tb³⁺ in POCl₃:SnCl₄ aprotic solvent has been examined. It is found that at a concentration of 10⁻¹ M Tb³⁺, the fluorescence exclusively originates from the⁵D₄ level. The appreciable increase in the decay times of Tb³⁺ in this solvent compared to its values in H₂O or D₂O, suggests that the decrease in non-radiative relaxations is due to the low energy vibrations characteristic of this solvent. Non-radiative transfer of energy from Tb³⁺ → Nd³⁺ and from Tb³⁺ → Ho³⁺ in this solvent has been established by examining the lifetime data. Calculated values of energy transfer probabilities (P_da) in the liquid air temperature are analysed to obtain a clue regarding the nature of excitation transfer mechanism. In both the systems, the energy transfer from Tb³⁺ donors to Nd³⁺ as well as Ho³⁺ acceptors, occurs predominantly via a dipole-dipole process. At high temperature the energy transfer is increased.