A spectroscopic and photochemical study of Ag +-, Cu 2+-, Hg 2+-, and Bi 3+-doped Cd xZn 1−xS nanoparticles

Abstract

A combination of stationary and time-resolved absorption and photoluminescence spectroscopy with flash and steady-state photolysis of Ag +, Cu 2+, Hg 2+, or Bi 3+-doped Cd x Zn 1− x S nanoparticles was used to assess the nature of the doping influence upon the optical properties of Cd x Zn 1− x S nanoparticles. The relationships between the type and the concentration of a dopant and the dynamics of the photoinduced processes in the doped nanoparticles are derived and discussed. A correlation is found between the magnitude of doping-induced changes in the intensity and decay dynamics of the deep trap photoluminescence and an enhancement of the transient bleaching recovery and acceleration of the photocorrosive degradation of the doped Cd x Zn 1− x S NPs compared to the undoped ones. The impact of the dopant upon the intensity of the luminescence and microsecond transient bleaching bands was found to grow substantially from Ag + to Cu 2+, Hg 2+ and Bi 3+. The same trend was found to hold for the acceleration of the steady-state photochemical corrosion of doped Cd x Zn 1− x S nanoparticles. The differences among the effect of the dopant ions studied were interpreted in terms of the depth and charge of surface states created by Cd 2+ (Zn 2+) substitution by a dopant.