QLCR Spectroscopy of Solid Nitrogen

Quadrupolar level crossing resonance (QLCR) occurs in the muSR of solids with diamagnetic muon states in close proximity to quadrupolar nuclei. This effect provides uniquely valuable sensitivity to charge states in muSR. Recent progress in the computation of muon states in materials using density functional theory (DFT+mu) can also be applied to predicting and interpreting QLCR spectra. Solid nitrogen provides an excellent example system to test these calculations against experiment. In our latest muon studies of solid nitrogen two key discoveries are firstly the presence of negative diamagnetic muon states, along with the usual positive states, and secondly an anomalously fast relaxation rate for some of the resonances. The QLCR spectra are strongly temperature dependent and further studies are needed to establish the full dependence and relate it to properties of the molecular solid

四极能级交叉共振（Quadrupolar Level Crossing Resonance，QLCR）存在于抗磁性μ子态（diamagnetic muon states）与四极核（quadrupolar nuclei）紧邻的固态材料的μ子自旋谱学（muSR）中。该效应对μ子自旋谱学中的电荷态具备独特且极具价值的探测灵敏度。近年来基于结合μ子的密度泛函理论（DFT+μ）计算材料中μ子态的研究进展，同样可用于预测与解析四极能级交叉共振谱。固态氮是对照实验验证上述计算方法的绝佳模型体系。在我们最新的固态氮μ子研究中，取得了两项关键发现：其一，除常规正电荷抗磁性μ子态外，还存在负电荷抗磁性μ子态；其二，部分共振信号呈现出反常快速的弛豫速率。四极能级交叉共振谱具有显著的温度依赖性，后续仍需开展进一步研究以明确其完整的温度依赖规律，并将其与该分子固态的相关性质建立关联。