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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Explanation of Spin-Lattice Relaxation Rates of Spin Labels Obtained with Multifrequency Saturation Recovery EPR
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Explanation of Spin-Lattice Relaxation Rates of Spin Labels Obtained with Multifrequency Saturation Recovery EPR

机译：多频饱和恢复EPR获得的自旋标记的自旋格弛豫速率的解释

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摘要

Electron paramagnetic resonance (EPR) pulsed saturation recovery (pSR) measurements of spin-lattice relaxation rates have been made on nitroxide-containing fatty acids embedded in lipid bilayers by Hyde and co-workers.The data have been collected for a number of spin-labeled fatty acids at several microwave spectrometer frequencies (from 2 to 35 GHz).We compare these spin-lattice relaxation rates to those predicted by the Redfield theory incorporating several mechanisms.The dominant relaxation mechanism at low spectrometer frequencies is the electron-nuclear dipolar (END) process,with spin rotation (SR),chemical shift anisotropy (CSA),and a generalized spin diffusion (GSD) mechanism all contributing.The use of a wide range of spectrometer frequencies makes clear that the dynamics cannot be modeled adequately by rigid-body isotropic rotational motion.The dynamics of rigid-body anisotropic rotational motion is sufficient to explain the experimental relaxation rates within the experimental error.More refined models of the motion could have been considered,and our analysis does not rule them out.However,the results demonstrate that measurements at only two suitably chosen spectrometer frequencies are sufficient to distinguish anisotropic from isotropic motion.The results presented demonstrate that the principal mechanisms responsible for anisotropically driven spin-lattice relaxation are well understood in the liquids regime.
机译：海德（Hyde）和他的同事对嵌入脂质双层中的含氮氧化物的脂肪酸进行了电子顺磁共振（EPR）脉冲饱和恢复（pSR）测量，研究了许多自旋在几个微波光谱仪频率（从2到35 GHz）上标记的脂肪酸。我们将这些自旋晶格弛豫速率与Redfield理论结合了几种机理的预测值进行了比较。 END）过程，其中自旋旋转（SR），化学位移各向异性（CSA）和广义自旋扩散（GSD）机理都起作用。使用广泛的光谱仪频率可以清楚地表明，不能用刚性对动力学进行充分建模体各向同性旋转运动。刚体各向异性旋转运动的动力学足以解释实验中的实验弛豫率。升error.More精致运动的模型可以被认为，我们的分析，不排除他们out.However，结果表明，在测量只有两个选择合适的光谱仪频率足以从呈现各向同性motion.The结果表明区分各向异性在液体状态下，对各向异性驱动的自旋晶格弛豫的主要机理已广为人知。

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