Radioluminescence and thermoluminescence properties of X-ray-irradiated pure CsI

The 25-280 K radioluminescence (RL) and thermoluminescence (TL) spectra in a nominally pure CsI have been studied. Strong emissions at 250-400 nm consist of two bands at 305 and 340 nm associated with the VK+e and H+F-type self-trapped excitons (STEs), respectively. There are some weak extrinsic signals in RL. The temperature dependence and the response of the two main bands to the X-ray tube voltage have been studied. It has been found that the dominant TL signals are associated with contamination of the sample, though the trapping levels are still characterised by the host lattice. A temperature shift between the intrinsic and extrinsic TL peaks has been observed in the thermal emissions at ∼55 and ∼82 K.