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Luminescent decay and spectra of impurity-activated alkali halides under high pressure

机译:高压下杂质活化碱卤化物的发光衰减和光谱

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摘要

The effect of high pressure on the luminescence of alkali halides doped with the transition-metal ions Cu+ and Ag+ and the heavy-metal ions In+ and Tl+ was investigated to 140 kbar. Measurement of spectra allowed the prediction of kinetic properties, and the predictions agree with lifetime data.In view of the localized nature of the electronic transitions, a pressure-dependent single configuration coordinate model is used to interpret the luminescence data. While pressure affects the volume, it also couples to the nontota1ly symmetric coordinates that determine the lifetime in the phosphors studied here. Luminescent kinetics are governed by the assistance of odd phonons for Cu+ and Ag+, and by Jahn-Te11er distortions for In+ and Tl+.Analysis of room-temperature measurements of emission peak location and peak ha1fwidth yields parameters characteristic of the potential wells of transition-metal ions in alkali halides. Using a pressure-dependent model of phonon-assisted transitions, these parameters predict the change in lifetime with pressure. Agreement between calculation and the experimentally determined lifetime is reasonable. The possibilities and limitations of the analysis are discussed.Measurements of steady-state intensity and lifetime were made over a range of pressures (4 to 60 kbar) and temperatures (100 to 3oo0 K) forfive aikali halide crystals doped with In+ and n+. The emission spectrum is a doublet (or a triplet in the case of CsI:Tl), caused by a Jahn-Teller splitting of the excited state. The relative intensity distribution of the spectral peaks as a function of temperature and pressure determines the parameters for a model of two levels in "dynamic equilibrium." The same model predicts lifetime changes with temperature and pressure which are in excellent agreement with the data for the In+-doped compounds. For the Tl+-doped compounds, metastable states control the lifetime, and parameters are extracted from the data for a multi-level model. Level splittings, level degeneracies, and intrinsic radiative rates are among the parameters determined in this study.Lifetimes were found from low-light level decay curves recorded after pulsed light excitation. A signal-averaging transient digitizer was used for lifetimes from one microsecond to five seconds. The single-photon counting method was employed for fast lifetimes of one hundred nanoseconds to fifty microseconds.
机译:研究了高压对掺有过渡金属离子Cu +和Ag +以及重金属离子In +和Tl +的碱金属卤化物发光的影响,达到140 kbar。光谱的测量可以预测动力学性质,并且该预测与寿命数据一致。鉴于电子跃迁的局部性质,使用压力相关的单一构型坐标模型来解释发光数据。尽管压力会影响体积,但压力还会耦合到非对称对称坐标,该坐标决定了此处研究的荧光粉的寿命。发光动力学受Cu +和Ag +的奇数声子的辅助以及In +和Tl +的Jahn-Te11er畸变的控制。发射峰位置和峰宽的室温测量分析产生了过渡金属势阱的特征参数碱卤化物中的离子。这些参数使用声子辅助跃迁的压力相关模型来预测寿命随压力的变化。计算与实验确定的寿命之间的一致性是合理的。讨论了该分析的可能性和局限性。对五个掺杂In +和n +的阿卡利卤化物晶体在一定压力(4至60 kbar)和温度(100至3oo0 K)范围内进行了稳态强度和寿命的测量。发射光谱是由激发态的Jahn-Teller分裂引起的二重峰(在CsI:Tl的情况下为三重峰)。光谱峰的相对强度分布与温度和压力的关系决定了“动态平衡”中两个水平模型的参数。相同的模型预测寿命随温度和压力的变化,这与In +掺杂化合物的数据非常吻合。对于掺有Tl +的化合物,亚稳态控制着寿命,并且从数据中提取了用于多级模型的参数。能级分裂,能级简并性和固有辐射率是这项研究确定的参数。生命是从脉冲光激发后记录的低光能级衰减曲线中发现的。信号平均瞬态数字化仪的使用寿命为1微秒至5秒。采用单光子计数方法可实现100纳秒至50微秒的快速寿命。

著录项

  • 作者

    Klick David Ira;

  • 作者单位
  • 年度 1977
  • 总页数
  • 原文格式 PDF
  • 正文语种 {"code":"en","name":"English","id":9}
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