标题： 低温自旋3/2核四极共振：通过拉比频率测角法研究自旋弛豫和电场梯度 显示英文标题

标题： Cryogenic spin 3/2 nuclear quadrupole resonance: Spin relaxation and electric field gradient via Rabi frequency goniometry

摘要： 介绍了一种在自旋为 3/2 的单晶样品上测定电场梯度 $-$ 主轴框架 (EFG-PAF) 的直接方法。 利用核四极子共振 (NQR) 谱，通过比较粉末和单晶样品的 NQR 信号，确定了氯酸钾 (KClO$_3$) 单晶中 $^{35}$Cl 的拉比频率。 通过利用拉比频率与激发方向的几何依赖性，可以轻松确定 EFG-PAF。 此外，在从 $17~\textrm{K}$ 到 $200 ~$K 的多个温度下测量了弛豫时间 $T_1$ 和 $T_2^*$，将先前研究的结果扩展到新的弛豫机制占主导地位的更低温度。 实验是在无低温恒温器中进行的，与传统的低温冷却装置相比，这带来了明显的挑战。 NQR探针在无低温恒温器内的成功运行有可能使该技术更易于获取并扩大应用范围。 显示英文摘要

摘要： A straightforward way to determine the electric field gradient $-$ principal axes frame (EFG-PAF) on single crystal samples with spin 3/2 nuclei is demonstrated. Nuclear quadrupole resonance (NQR) spectroscopy is used to determine the Rabi frequency for $^{35}$Cl in a single crystal of potassium chlorate (KClO$_3$) by comparing the NQR signal for powder and single crystal samples. By exploiting the geometrical dependence of the Rabi frequency with respect to the excitation direction, EFG-PAF is readily determined. Furthermore, relaxation times $T_1$ and $T_2^*$ were measured at multiple temperatures ranging from $17~\textrm{K}$ to $200 ~$K, extending the results of previous works to colder temperatures where new relaxation mechanisms become dominant. The experiments were performed in a cryogen-free cryostat, which posed distinct challenges compared to a conventional cryogenic cooling setup. The successful operation of the NQR probe within a cryogen-free cryostat has the potential to make the technique more accessible and widen applications.