Spectroscopic properties of rare earths in K5Bi1-x(RE)x(MoO4)4 crystals

The luminescence of the RE=Pr3+, Eu3+, Nd3+ ions in K5Bi1-x(RE)x(MoO4)4 (x=1) crystals has been investigated by using steady-state and time-resolved laser spectroscopy. The Pr3+ emission in these crystals, at low dopant concentrations, are characterized by an intense 1D2→3H4 red luminescence. Under excitation in the 3P0 state the crystals show emission from both 3P0 and 1D2 levels. At Pr3+ concentrations higher than x=0.005, even at 4.2 K, the 1D2 level shows a strong concentration quenching. Site-selective spectroscopy of the 3P0 level exhibits remarkable site effects. Resonant fluorescence line narrowing spectroscopy of the 5D0 level of Eu3+ shows the existence of two main broad crystal field site distributions for the europium ion, together with two other minor distinguishable sites. Referring to Nd3+, the time-resolved 4F3/2→4I9/2 emission spectra obtained by exciting in the 4G5/2 level show features which may suggest the presence of more than one Nd3+ site. (orig.)