Photoluminescence spectra of thin films containing CdSe/ZnS quantum dots irradiated by 532-nm laser radiation and gamma-rays

We have investigated temporal behavior of the photoluminescence (PL) spectra of thin films containing CdSe/ZnS quantum dots irradiated by 532 nm laser radiation and gamma-rays. Under ∼100 W/cm2 laser radiation, the PL intensity (IPL) increases with irradiation time upto about 500 s and thereafter declines linearly. The wavelength of the PL emission (λpeak) exhibits a blue-shift with exposure time. Upon simultaneous irradiation by 100 W/cm2 532-nm laser, as well as 0.57 and 1.06 MeV gamma-rays, the temporal behaviors of both IPL and λpeak are significantly different; IPL increases to a saturation level, and the magnitude of the blue-shift in λpeak is reduced. We discuss possible mechanisms underlying these results.