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)(MoO 4)(4) (x less than or equal to 1) crystals has been investigated by us ing steady-state and time-resolved laser spectroscopy. The Pr3+ emissi on in these crystals, at low dopant concentrations, are characterized by an intense D-1(2)-->H-3(4) red luminescence. Under excitation in th e P-3(0) state the crystals show emission from both P-3(0) and D-1(2) levels. At Pr3+ concentrations higher than x=0.005, even at 4.2 K, the D-1(2) level shows a strong concentration quenching. Site-selective s pectroscopy of the P-3(0) level exhibits remarkable site effects. Reso nant fluorescence line narrowing spectroscopy of the D-5(0) level of E u3+ shows the existence of two main broad crystal field site distribut ions for the europium ion, together with two other minor distinguishab le sites. Referring to Nd3+, the time-resolved F-4(3/2)-->I-4(9/2) emi ssion spectra obtained by exciting in the (4)G(5/2) level show feature s which may suggest the presence of more than one Nd3+ site. (C) 1998 Elsevier Science S.A.