γ-CuI晶体的发光衰减时间和对X射线的能量响应

采用溶剂蒸发法生长出透明的带隙宽度为2.96 eV的γ-CuI晶体。在紫外光激发下, 该晶体在410、430 nm处分别呈现有近带边发射峰, 另在720 nm附近还出现一个与样品碘缺陷有关的宽发射带。经碘退火后, 样品720 nm发射带被基本抑制, 而在420 nm处出现了一个更强的近带边发射峰。使用扫描相机分别测量了γ-CuI晶体各发射峰(带)的衰减时间谱, 其中近带边发射峰的发光衰减时间常数均在数十皮秒量级, 表明γ-CuI晶体具有极快的时间响应特性; 而720 nm发射带的发光衰减时间常数主要在数十纳秒量级。X射线激发下, γ-CuI晶体具有435 nm近带边发射峰和680 nm发射带, 其近带边发射对X射线能量响应的测量结果表明, 当E_X<49.1 keV时, γ-CuI晶体闪烁光快分量对X射线的探测效率相对较高。

Fluorescent Decay Time and Energy Response of γ-CuI Crystal

γ-CuI crystal was prepared by using slow solvent evaporation method. The optical transmission spectrum reveals that the crystal is transparent with band gap of 2.96 eV. Two near-band-edge emission peaks are located at 410 nm, 430 nm, and an iodine related defect emission band near 720 nm of the crystal appear under UV excitation. The emission band near 720 nm can be suppressed by iodine annealing, while a new and relative strong near-band-edge emission peaked at 420 nm appears. Decay times of emission peaks and band of γ-CuI crystals were measured by using streak camera. The results show that the decay times of all near-band-edge emission peaks are tens of picosecond, which indicates that γ-CuI crystal is one of the fastest scintillators, but the decay time of the emission band near 720 nm is mainly tens of nanosecond. γ-CuI crystal presents a near-band-edge emission peaked at 435 nm and a broad emission band near 680 nm under X-ray excitation. The energy response of the near- band-edge emission to X-ray shows that the emission has a relatively high response to X-ray when the X-ray energy is less than 49.1 keV.