Optical spectroscopy of undoped PbWO4 powders with different annealing atmospheres

The photoacoustic spectrum, which is performed for the first time, optical reflection, and excitation and emission spectra of undoped PbWO4 powders wi th different annealing atmospheres were compared and analyzed. The red shif ts of the absorption edge and the increased absorption around 425 and 600-8 00 nm in the vacuum annealed sample with respect to that in the oxygen anne aled sample indicate the decrease of the O- centers in the sample. The incr ease of the blue luminescence in a vacuum annealing atmosphere suggests tha t annealing under vacuum atmosphere produces PbWO4 crystals with a better l ight yield. (C) 1999 Elsevier Science B.V. All rights reserved.