Vugmeyster Liliya, Fu Riqiang, Ostrovsky Dmitry
Department of Chemistry, University of Colorado Denver, Denver, CO, 80204, USA.
National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.
Solid State Nucl Magn Reson. 2024 Dec;134:101976. doi: 10.1016/j.ssnmr.2024.101976. Epub 2024 Nov 20.
O NMR methods are emerging as a powerful tool for determination of structure and dynamics in materials and biological solids. We present experimental and theoretical frameworks for measurements of O NMR relaxation times in static solids focusing on the excitation of the central transition of the O spin 5/2 system. We employ O-enriched NaNO as a model compound, in which the nitrate oxygen atoms undergo 3-fold jumps. Rotating frame (T), transverse (T) and longitudinal (T) relaxation times as well as line shapes were measured for the central transition in the 280 to 195 K temperature range at 14.1 and 18.8 T field strengths. We conduct experimental and theoretical comparison between different relaxation methods and demonstrate the advantage of combining data from multiple relaxation time and line shape measurements to obtain a more accurate determination of the dynamics as compared to either of the techniques alone. The computational framework for relaxation of spin 5/2 nuclei is developed using the numerical integration of the Liouville - von Neumann equation.
氧核磁共振方法正在成为一种用于确定材料和生物固体结构与动力学的强大工具。我们提出了用于测量静态固体中氧核磁共振弛豫时间的实验和理论框架，重点关注氧自旋5/2系统中心跃迁的激发。我们使用富含氧的硝酸钠作为模型化合物，其中硝酸根氧原子经历三重跳跃。在14.1和18.8 T场强下，在280至195 K温度范围内测量了中心跃迁的旋转坐标系（T₁ρ）、横向（T₂）和纵向（T₁）弛豫时间以及线形。我们对不同弛豫方法进行了实验和理论比较，并证明了与单独使用任何一种技术相比，结合多个弛豫时间和线形测量数据以更准确地确定动力学的优势。利用刘维尔 - 冯·诺依曼方程的数值积分开发了自旋5/2核弛豫的计算框架。
