Mykhaylyk V B, Kraus H, Bobb L, Gamernyk R, Koronski K
Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK.
University of Oxford, Department of Physics, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK.
Sci Rep. 2019 Mar 27;9(1):5274. doi: 10.1038/s41598-019-41768-z.
Realtime in situ temperature monitoring in difficult experimental conditions or inaccessible environments is critical for many applications. Non-contact luminescence decay time thermometry is often the method of choice for such applications due to a favorable combination of sensitivity, accuracy and robustness. In this work, we demonstrate the feasibility of an ultrafast PbI scintillator for temperature determination, using the time structure of X-ray radiation, produced by a synchrotron. The decay kinetics of the scintillations was measured over the 8-107 K temperature range using monochromatic pulsed X-ray excitation. It is found that lead iodide exhibits a very fast and intense scintillation response due to excitons and donor-acceptor pairs, with the fast decay component varying between 0.08 and 0.5 ns - a feature that can be readily exploited for temperature monitoring. The observed temperature dependence of the decay time is discussed in terms of two possible mechanisms of thermal quenching - transition over activation barrier and phonon-assisted escape. It is concluded that the latter provides a better fit to the experimental results and is consistent with the model of luminescence processes in PbI. We evaluated the sensitivity and estimated the accuracy of the temperature determination as ca. ±6 K at 107 K, improving to ±1.4 K at 8 K. The results of this study prove the feasibility of temperature monitoring, using ultrafast scintillation of PbI excited by X-ray pulses from a synchrotron, thus enabling non-contact in-situ cryothermometry with megahertz sampling rate.
在困难的实验条件或难以接近的环境中进行实时原位温度监测对许多应用来说至关重要。非接触式发光衰减时间测温法由于灵敏度、准确性和稳健性的良好结合，常常是此类应用的首选方法。在这项工作中，我们利用同步加速器产生的X射线辐射的时间结构，证明了一种超快PbI闪烁体用于温度测定的可行性。使用单色脉冲X射线激发在8 - 107 K温度范围内测量了闪烁的衰减动力学。发现碘化铅由于激子和供体 - 受体对而表现出非常快速且强烈的闪烁响应，快速衰减分量在0.08至0.5 ns之间变化——这一特性可很容易地用于温度监测。从热猝灭的两种可能机制——越过激活势垒的跃迁和声子辅助逃逸——的角度讨论了观察到的衰减时间的温度依赖性。得出的结论是，后者与实验结果拟合得更好，并且与PbI中的发光过程模型一致。我们评估了灵敏度并估计了温度测定的准确性，在107 K时约为±6 K，在8 K时提高到±1.4 K。这项研究的结果证明了利用同步加速器产生的X射线脉冲激发PbI的超快闪烁进行温度监测的可行性，从而能够以兆赫兹采样率进行非接触式原位低温测温。
