Lin Richeng, Zheng Wei, Chen Liang, Zhu Yanming, Xu MengXuan, Ouyang Xiaoping, Huang Feng
State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, 510275, Guangzhou, China.
State Key Laboratory of Intense Pulsed Radiation Simulation and Effect and Radiation Detection Research Center, Northwest Institute of Nuclear Technology, 710024, Xi'an, China.
Nat Commun. 2020 Aug 28;11(1):4351. doi: 10.1038/s41467-020-18221-1.
Phosphorescence is a fascinating photoelectronic phenomenon usually observed in rare-earth-doped inorganic crystals and organic molecular crystals, owning great potential in optical information storage, color display and biological dosimetry. Here, we present an ultralong intrinsic phosphorescence (>20,000 seconds) in AlN single-crystal scintillator through X-ray excitation. We suggest that the long afterglow emission originates from the intra-band transition related to native nitrogen vacancy. Some excited states formed by absorbing X-ray photons cannot satisfy the parity difference between initial and final states required by transition selection rule, so they cannot return to the ground state directly through radiation transitions but through several phonon-assisted intra-band transitions slowly. During this process, a long-term broad-spectra phosphorescence emission is formed. Investigating the X-ray excited phosphorescence emission in the AlN is of great significance to understanding the mechanism of phosphorescence in inorganic materials, and to realizing the practical applications in high-energy ray dosimetry.
磷光是一种迷人的光电现象，通常在稀土掺杂的无机晶体和有机分子晶体中观察到，在光信息存储、彩色显示和生物剂量测定方面具有巨大潜力。在此，我们通过X射线激发在AlN单晶闪烁体中呈现出超长的本征磷光（>20,000秒）。我们认为，长余辉发射源于与原生氮空位相关的带内跃迁。一些通过吸收X射线光子形成的激发态不满足跃迁选择规则要求的初末态之间的宇称差，因此它们不能通过辐射跃迁直接回到基态，而是通过几个声子辅助的带内跃迁缓慢返回。在此过程中，形成了长期的宽光谱磷光发射。研究AlN中的X射线激发磷光发射对于理解无机材料中的磷光机制以及实现高能射线剂量测定的实际应用具有重要意义。
