FAST LUMINESCENCE OF UNDOPED PBWO4 CRYSTAL

The results of an investigation of PbWO4 luminescence properties obtai ned by time-resolved techniques under VUV, X-ray synchrotron radiation and gamma-radiation excitation are presented. The fast luminescence i n the 430 nm band with fwhm of 0.5 eV is characterized by a decay time of about 4-5 ns under X-ray excitation. A slow luminescence with deca y time of more than 1 mu s can be attributed to a green emission band. An intermediate decay time was also detected. This time changes from 20 ns (for 360 nm emission) to 50 ns (for 550 nm). The PbWO4 fast band excitation spectrum and reflectivity were measured in the fundamental absorption region using VUV synchrotron radiation (4-150 eV). A compa rison between these two spectra allowed us to suppose the excitonic ty pe of the excitation mechanism of the fast emission band. The role of pb(2+) ions in the PbWO4 luminescence is discussed.