Luminescence and scintillation properties of Cs₃BiCl₆ crystals

The optical and scintillation properties of Cs₃BiCl₆ single crystals were characterized, and absorption properties were investigated for thin films. The thin films showed two absorption bands at ∼220 nm and 330 nm; these bands can be attributed to the ¹A_1g → ¹T_1u and ¹A_1g → ³T_1u transitions of Bi³⁺ ions, respectively. A luminescence band was observed at ∼390 nm in the photoluminescence spectra; this band can be attributed to the ³T_1u → ¹A_1g transition of Bi³⁺ ions. In the X-ray-induced radioluminescence spectrum, in addition to the luminescence band at 390 nm, another band was observed at 600–700 nm; this band was tentatively attributed to the radiative recombination of self-trapped excitons. The decay-time constants of photoluminescence and scintillation decay were of the order of nanoseconds. The scintillation light yield was 800 photons/MeV. The results indicate that Cs₃BiCl₆ has a fast scintillation decay and a relatively poor light yield.