M. D. Birowosuto, P. Dorenbos, C. W. E. van Eijk, K. W. Krämer and H U Güdel
Scintillation properties and anomalous Ce³⁺ emission of Cs₂NaREBr₆:Ce³⁺ (RE = La,Y,Lu)
J. Phys.: Condens. Matter 18, 6133-6148 (2006)                 

Abstract: We report the optical and scintillation properties of the Ce³⁺-doped bromoelpasolites Cs₂NaREBr₆ (RE = La,Y,Lu). The g-ray scintillation light yield of these materials varies from 6000 to 17 000 photons per MeV absorbed g-ray energy. At room temperature (RT), the g-ray scintillation decay curves for all compounds show a fast component of 61 ns, whereas the intrinsic Ce³⁺ decay time is 30 ns. The scintillation mechanism in elpasolites is addressed. In Cs₂NaLuBr₆:Ce³⁺ and Cs₂NaYBr₆:Ce³⁺, we observe for the first time the so-called Ce³⁺ anomalous emission in bromide compounds. This emission previously observed for chloride compounds is an ultrafast Ce³⁺ emission with a selective excitation mechanism. The decay time of the anomalous emission at 10 K in bromide compounds (7.80 ns) is faster than that in chloride compounds (9.90 ns). Two bands of the anomalous emission are resolved for the first time. The mechanism behind this emission is discussed.