Excitonic emission of scheelite tungstates AWO(4) (A = Pb, Ca, Ba, Sr)

Self-trapped exciton emission spectra of four scheelite tungstate single cr ystals AWO(4) (A = Pb, Ca, Sr, Ba) were measured in a wide temperature rang e and their structure is discussed. We present decay kinetics of PbWO4 in 0 .35-300 K range and a mathematical model, which successfully approximates t emperature dependencies of the decay rime and intensity with a unique set o f parameters. Besides the usual thermal quenching also thermally induced ex citon disintegration, which has been evidenced in earlier experiments, is c onsidered. (C) 2000 Elsevier Science B.V. All rights reserved.