Kruk Danuta, Kowalewski Jozef, Westlund Per-Olof
Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, S-10691, Sweden.
J Chem Phys. 2004 Aug 1;121(5):2215-27. doi: 10.1063/1.1768168.
A model of the paramagnetic relaxation enhancement is developed in terms of electron-spin relaxation caused by the zero-field splitting (ZFS) fluctuating in time due to a coupling between the electron-spin variables and quantum vibrations. The ZFS interaction provides a coupling between the electron-spin variables and vibrational degrees of freedom, and is represented as a Taylor series expansion in a set of vibrational modes (normal coordinates). A two-level harmonic oscillator subsystem is assumed, and the electron-spin relaxation associated with T2V and T1V vibrational relaxation is considered. The description of vibrationally induced electron-spin dynamics is incorporated into the calculations of the paramagnetic relaxation enhancement by the Solomon-Bloembergen-Morgan approach as well as in the framework of the general slow-motion theory. The theoretical predictions are compared with the experimental paramagnetic relaxation enhancement values for the Ni(H2O)6(2+) complex in aqueous solution. The parameters required by the model are obtained from quantum chemical and molecular dynamics studies. Comparison is made between the current model and its recently published classical counterpart.
基于电子自旋弛豫建立了顺磁弛豫增强模型，该弛豫是由电子自旋变量与量子振动之间的耦合导致零场分裂（ZFS）随时间波动引起的。ZFS相互作用提供了电子自旋变量与振动自由度之间的耦合，并表示为一组振动模式（正则坐标）中的泰勒级数展开。假定存在一个两能级简谐振子子系统，并考虑与T2V和T1V振动弛豫相关的电子自旋弛豫。通过所罗门 - 布洛姆伯根 - 摩根方法以及在一般慢运动理论的框架内，将振动诱导的电子自旋动力学描述纳入顺磁弛豫增强的计算中。将理论预测结果与水溶液中Ni(H2O)6(2+)配合物的实验顺磁弛豫增强值进行了比较。该模型所需的参数来自量子化学和分子动力学研究。对当前模型与其最近发表的经典对应模型进行了比较。
