Abstract
Infrared stimulated luminescence (ISL) occurred in CaS:Eu,Sm due to formation of luminescent centres Eu2+ and electron trapping centres Sm3+. The electron trapping centres Sm3+ became occupied (forming Sm2+ by trapping excited electrons) in photoluminescence (PL) excitation (PLX) process causing simultaneous ionization of luminescent centres Eu2+ (leaving Eu3+ by losing an electron or capturing a hole). In this paper, the electron trapping in PLX and the recombination in ISL were examined by the time-related PL and ISL spectra of CaS:Eu,Sm. The spectroscopic evidence confirmed that the ISL in CaS:Eu,Sm was produced due to recombination of de-trapped electrons and previously ionized luminescent centres (Eu3+). It was believed that the electron trapping occurred concurrently as occurrence of the PL of Eu2+ in PLX process. However, the recombination of de-trapped electrons and previously ionized luminescent centres took about 10 μs or even more to occur after infrared irradiation.
Published Version
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