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

We present a detailed investigation of the quantum efficiency of the S-1(0) and P-3(0.1) levels in Pr3+ doped YF3 under VUV excitation. The quantum efficiency of the P-3(0.1) level was determined by the measurement and comparison of the photon fluxes of the S-1(0) --> I-1(6) transition around 400 nm with the visible emissions occurring from the P-3(0.1) levels. It was found that already at concentrations as low as 0.01% the P-3(0.1) emission quantum efficiency is only about 61%. The quenching process is most probable caused by an energy transfer cross relaxation process involving the P-3(0.1) levels and the H-3(4) 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 P-3(0,1) quenching is only moderate. (C) 2004 Elsevier B.V. All rights reserved.