Photoluminescence of CaS: Ce, Na Phosphor

Abstract

The photoluminescence and excitation spectra for the CaS: Ce, Na phosphor were measured at liquid nitrogen temperature. The photoluminescence spectrum was identical to the cathodoluminescence spectrum. The excitation spectrum is explained by employing the reflectivity data of single crystal CaS; the structure of the excitation spectrum can be assigned to the singular point in the band structure. From the excitation spectrum it is speculated that CaS has an indirect allowed transition at its band edge.