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PACS: 71.35.Cc; 78.40.Ha The fundamental absorption tail of single PbWO 4 crystals has been investigated in the temperature range of 6-300 K. The absorption coefficient in the tail region is found to obey the Urbach rule, with the steepness parameter s 0 = 0.82 and the effective phonon energy hw = 32 meV. The present results are discussed in terms of the Sumi and Toyozawa theory on Urbach edges, indicating that they are consistent with other experimental results.

This paper reports the decay kinetics of the intrinsic blue luminescence from self-trapped excitons in lead tungstate excited by a Nd:YAG laser. The kinetics exhibits some complicated features, depending strongly on the experimental conditions, such as laser power, sample temperature, and one- or two-photon excitation. The result indicates that the self-trapped excitons interact with each other under high-density excitation, thereby shortening the decay time of the blue luminescence. Furthermore, a noticeable rise component is observed under two-photon excitation in the temperature range of 50–150 K. The contribution of radiation-induced defect centres in the process of energy transfer from Pb sites to WO4 sites is discussed.

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