Luminescence concentration quenching of D2 state in YPO4:Pr

Under selective excitation of the P0 level of the Pr3+ ion in YPO4, the emission spectra and fluorescence decay curves were measured at different concentrations and temperatures. The origin of the spectral line located at 16 318 cm−1 (612.8 nm) was discussed and attributed to the D2 → H4 transition. The process of concentration quenching for the D2 state was also studied. Using the Inokuti–Hirayama model, the non-exponential fluorescence decay curves of the D2 level were fitted. The result shows that dipole– quadrupole interaction between Pr3+ ions, which causes D2 → G4 and H4 → F4 cross-relaxation, results in the quenching of D2 emissions.