Electron paramagnetic resonance (EPR) is used to monitor photoinduced changes in the charge states of sulfur vacancies and Cu ions in tin hypothiodiphosphate. A Sn₂P₂S₆ crystal containing Cu⁺ (3d¹⁰) ions at Sn²⁺ sites was grown by the chemical vapor transport method. Doubly ionized sulfur vacancies ($V_S^{2+}$) are also present in the as-grown crystal (where they serve as charge compensators for the Cu⁺ ions). For temperatures below 70 K, exposure to 532 or 633 nm laser light produces stable Cu²⁺ (3d⁹) ions, as electrons move from Cu⁺ ions to sulfur vacancies. A g matrix and a ^63,65Cu hyperfine matrix are obtained from the angular dependence of the Cu²⁺ EPR spectrum. Paramagnetic singly ionized ($V_S^{+}$) and nonparamagnetic neutral ($V_S^0$) charge states of the sulfur vacancies, with one and two trapped electrons, respectively, are formed during the illumination. Above 70 K, the neutral vacancies ($V_S^0$) are thermally unstable and convert to $V_S^{+}$ vacancies by releasing an electron to the conduction band. These released electrons move back to Cu²⁺ ions and restore Cu⁺ ions. Analysis of isothermal decay curves acquired by monitoring the intensity of the Cu²⁺ EPR spectrum between 74 and 82 K, after removing the light, gives an activation energy of 194 meV for the release of an electron from a $V_S^0$ vacancy. Warming above 120 K destroys the $V_S^{+}$ vacancies and the remaining Cu²⁺ ions. The photoinduced EPR spectrum from a small concentration of unintentionally present Ni⁺ ions at Sn²⁺ sites is observed near 40 K in the Sn₂P₂S₆ crystal.

中文翻译：

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光致折射Sn2P2S6晶体中硫空位和铜离子处的光诱导电荷俘获

电子顺磁共振（EPR）用于监测次硫代二磷酸锡中硫空位和Cu离子的电荷状态的光诱导变化。通过化学气相传输法生长了在Sn ²⁺位点上包含Cu ⁺（3d ¹⁰）离子的Sn ₂ P ₂ S ₆晶体。双电离硫空位（$V_{\mathrm{小号}}^{\mathrm{2个}+}$）也存在于刚生长的晶体中（它们在其中充当Cu ⁺离子的电荷补偿剂）。对于低于70 K的温度，当电子从Cu ⁺离子移动到硫空位时，暴露于532或633 nm激光中会产生稳定的Cu ²⁺（3d ⁹）离子。从Cu ²⁺ EPR光谱的角度依赖性获得了一个g矩阵和一个^63,65 Cu超细矩阵。顺磁单电离（$V_{\mathrm{小号}}^{+}$）和非顺磁性中性点（$V_{\mathrm{小号}}^0$）在照明过程中分别形成一个和两个被捕获的电子的硫空位的电荷态。70 K以上，空缺（$V_{\mathrm{小号}}^0$）具有热不稳定性，并转换为 $V_{\mathrm{小号}}^{+}$通过将电子释放到导带来实现空位。这些释放的电子移回Cu ²⁺离子并恢复Cu ⁺离子。通过监测74和82 K之间的Cu ²⁺ EPR光谱的强度而获得的等温衰减曲线的分析，在去除光后，其激活能为194 meV，用于从电子中释放电子。$V_{\mathrm{小号}}^0$空缺。超过120 K变暖会破坏$V_{\mathrm{小号}}^{+}$空位和剩余的Cu ²⁺离子。在Sn ₂ P ₂ S ₆晶体中，在40 K附近观察到少量的Sn ²⁺处无意存在的Ni ⁺离子引起的光致EPR光谱。