Quantum efficiency of 1S0 and 3P0,1 levels of Pr3+ doped YF3

We present a detailed investigation of the quantum efficiency of the 1S0 and 3P0,1 levels in Pr3+ doped YF3 under VUV excitation. The quantum efficiency of the 3P0,1 level was determined by the measurement and comparison of the photon fluxes of the 1S0 → 1I6 transition around 400 nm with the visible emissions occurring from the 3P0,1 levels. It was found that already at concentrations as low as 0.01% the 3P0,1 emission quantum efficiency is only about 61%. The quenching process is most probable caused by an energy transfer cross relaxation process involving the 3P0,1 levels and the 3H4 ground state. For concentrations of 0.1%, 0.5%, 1% and 10%, the quantum efficiency was determined to be about 42%, 29%, 17%, and 0.4%, respectively. The total quantum efficiency of the visible emission (380-750 nm) under excitation at 190 nm, determined by measurements of the total photon flux, has a maximum for a Pr3+ concentration of 1%. At this value, the absorption efficiency of the 4f5d absorption bands is very high and the 3P0,1 quenching is only moderate.