Decay kinetics of the intrinsic luminescence in undoped and doped PbWO4 crystals excited by femtosecond laser

Decay kinetics of the luminescence in undoped and La3+- or Cd2+-doped PbWO4 (PWO) crystals has been studied under the excitation with the fourth harmonic light (300 nm) of a femtosecond laser at room temperature. The measurements are carried out by making use of a combination of a monochromator and a streak scope. The intrinsic “blue” luminescence at 440 nm in undoped PWO exhibits two fast decay components (1.5 and 13 ns). In addition, there appears a rise component of about 60 ps. The luminescence and decay characteristics of the doped PWO are essentially the same as those of the undoped one, i.e., there is no appearance of the extrinsic “green” luminescence in the later stage by doping of La3+ (1350 at ppm) or Cd2+ (1 at%) ions. It is found that the blue luminescence is enhanced in intensity by several 10% in these doped crystals. The influence of dopant ions on the decay kinetics and the luminescence intensity will be discussed.