Electron spin dynamics

D. Electron spin dynamics in the equilibrium ensemble Spin-dynamics models Outer-sphere relaxation... 

In all the approaches mentioned below, it is assumed that the correlation function can be factorized into a product of correlation functions for the three degrees of freedom rotational motion, translational diffusion and electron spin dynamics. 

The quantum alternative for the description of the vibrational degrees of freedom has been commented by Westlund et al. (85). The comments indicate that, to get a reasonable description of the field-dependent electron spin relaxation caused by the quantum vibrations, one needs to consider the first as well as the second order coupling between the spin and the vibrational modes in the ZFS interaction, and to take into account the lifetime of a vibrational state, Tw, as well as the time constant,T2V, associated with a width of vibrational transitions. A model of nuclear spin relaxation, including the electron spin subsystem coupled to a quantum vibrational bath, has been proposed (7d5). The contributions of the T2V and Tw vibrational relaxation (associated with the linear and the quadratic term in the Taylor expansion of the ZFS tensor, respectively) to the electron spin relaxation was considered. The description of the electron spin dynamics was included in the calculations of the PRE by the SBM approach, as well as in the framework of the general slow-motion theory, with appropriate modifications. The theoretical predictions were compared once again with the experimental PRE values for the Ni(H20)g complex in aqueous solution. This work can be treated as a quantum-mechanical counterpart of the classical approach presented in the paper by Kruk and Kowalewski (161). 

Kawai A, Shibuya K. Electron spin dynamics in a pair interaction between radical and electronically-excited molecule as studied by a time-resolved ESR method. J Photochem Photobiol C Photochem Rev 2006 7 89-103. 

In conclusion, the molecular motion seems to be well described, and the decomposition of the electron spin dynamics from the dipole-dipole interaction is a good approximation. However, the calculated electron spin relaxation was too slow to account for the paramagnetic relaxation, either because the ZFS was too small in magnitude or fluctuating too fast. The reorientation of the water could have a large effect on the ZFS, but unfortunately this was not included in the treatment due to the problems with describing it from symmetry modes. Also, non-linear terms in the property surface might be of importance for a proper description of the ZFS fluctuations. 

It has been shown in the preceding paper that the QED electronic stress tensor plays a fundamentally important role in order to understand the electron spin dynamics the spin torque and zeta force originated from the chiral nature of electron that is intrinsic to the spin-1/2 Fermion. The dynamics of electron spin with the realization of spin-orbit coupling has recently been of keen interest, particularly in the field of spin torque transfer in spintronics see recent review and the references cited therein. ... 

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