Luminescence and vibrational structure of CaS:Ce3+ and CaSe:Ce3+ phosphors

Excitation and emission spectra for CaS:Ce3+ and CaSe:Ce3+ phosphors are measured at 6, 80, and 300 K. The vibrational structure on the emission bands 2T/sub 2g/ → 2F/sub 5/2/, 2F/sub 7/2/ and the excitation band 2F/sub 5/2/ → 2T/sub 2g/ is analysed by the use of energy matrices in order to determine the coupling constant of spin-orbit interaction zeta/sub f/ and the crystal field parameters V4/sup (f)/, V6/sup (f)/ for the 4f orbit. In addition, some information on the transfer of the excitation energy from the host crystal to an unexcited Ce3+ ion is obtained by the aid of the diffused reflection spectra of CaS, CaSe, SrS, and SrSe phosphors containing no activator. (author)