The luminescence properties of CaS : Eu2+ excited by pico-second laser pulse

CaS : Eu2+ materials were prepared by using sulfur-flux method and analyzed with X-ray diffraction technology. The photoluminescence spectra of the sample excited by 532 nm pico-second laser pulse were investigated. The luminescence of Eu3+ as well as Eu2+ was observed. It revealed that some Eu2+ ions could be ionized to become Eu3+ ions when the sample was excited by the pico-second laser pulse. The dependence of the luminescence intensity of Eu3+ and that of Eu2+ on the concentration of Eu2+ was also observed. As luminescence peaks of Eu3+ were just in the region of Eu2+ absorption, the energy transfer from Eu3+ to Eu2+ would take place.