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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Scalar Relaxation of the Second Kind. A Potential Source of Information on the Dynamics of Molecular Movements. 3. A ~(13)C Nuclear Spin Relaxation Study of CBrX_3 (X = Cl, CH_3, Br) Molecules
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Scalar Relaxation of the Second Kind. A Potential Source of Information on the Dynamics of Molecular Movements. 3. A ~(13)C Nuclear Spin Relaxation Study of CBrX_3 (X = Cl, CH_3, Br) Molecules

机译：第二类的标量松弛。有关分子运动动力学的潜在信息来源。 3. CBrX_3（X = Cl，CH_3，Br）分子的〜（13）C核自旋弛豫研究

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摘要

Continuing studies based on measurements of the nuclear spin relaxation rates running via the SC2 mechanism (scalar relaxation of the second kind), we present in this work the results obtained for three bromo compounds: CBrCl_3, (CH_3)_3CBr, and CBr_4. A careful separation of saturation-recovery curves, measured for signals of ~(13)C nuclei at 7.05 and 11.7 T on two components, has provided the longitudinal SC2 relaxation rates of carbon signals in ~(79)Br and ~(81)Br containing isotopomers of the investigated compounds. These data have enabled experimental determination of spin-spin coupling constants and relaxation rates of quadrupole bromine nuclei, both types of parameters being hardly accessible by direct measurements. Investigation of the relaxation behavior of these molecules, being of similar size and shape, has provided quite different practical and interpretational problems which are likely to be encountered in relaxation studies of many other carbon-bromine systems. In order to evaluate the quality of the obtained experimental results, advanced theoretical calculations of the indirect ~1J(~(13)C,~(79)Br) coupling constants, magnetic shielding of carbon nuclei, and quadrupole coupling constants of bromines in the investigated compounds have been performed and compared with the experimental values. Relatively small divergences between experiment and theory have been found. The contributions of the relativistic effects to the values of the discussed parameters have been tentatively estimated.
机译：基于对通过SC2机制运行的核自旋弛豫速率（第二种标量弛豫）进行测量的持续研究，我们在这项工作中介绍了三种溴代化合物CBrCl_3，（CH_3）_3CBr和CBr_4的结果。仔细分离饱和-恢复曲线，对两个组分在7.05和11.7 T处〜（13）C核的信号进行测量，提供了〜（79）Br和〜（81）Br中碳信号的纵向SC2弛豫率。包含所研究化合物的同位素异构体。这些数据使得能够通过实验确定四极杆溴核的自旋-自旋耦合常数和弛豫率，这两种类型的参数很难通过直接测量获得。对这些具有相似大小和形状的分子的弛豫行为的研究提供了完全不同的实际和解释性问题，在许多其他碳溴系统的弛豫研究中可能会遇到这些问题。为了评估获得的实验结果的质量，对间接的〜1J（〜（13）C，〜（79）Br）耦合常数，碳核的磁屏蔽以及溴在其中的四极耦合常数进行了高级理论计算。进行了研究的化合物并将其与实验值进行比较。实验和理论之间的差异相对较小。相对论效应对所讨论参数值的贡献已被初步估算。

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