Free Energy Gap Dependence of the Electron-Transfer Rate from the Inverted to the Normal Region

Gayathri, N and Bagchi, B (1999) Free Energy Gap Dependence of the Electron-Transfer Rate from the Inverted to the Normal Region. In: Journal of Physical Chemistry A, 103 (42). pp. 8496-8504.

PDF jp991357w.pdf - Published Version Restricted to Registered users only Download (165kB) | Request a copy

Abstract

numerical study of the free energy gap (FEG) dependence of the electron-transfer rate in polar solvents is presented. This study is based on the generalized multidimensional hybrid model, which not only includes the solvent polarization and the molecular vibration modes, but also the biphasic polar response of the solvent. The free energy gap dependence is found to be sensitive to several factors, including the solvent relaxation rate, the electronic coupling between the surfaces, the frequency of the high-frequency quantum vibrational mode, and the magnitude of the solvent reorganization energy. It is shown that in some cases solvent relaxation can play an important role even in the Marcus normal regime. The minimal hybrid model involves a large number of parameters, giving rise to a diverse non-Marcus FEG behavior which is often determined collectively by these parameters. The model gives the linear free energy gap dependence of the logarithmic rate over a substantial range of FEG, spanning from the normal to the inverted regime. However, even for favorable values of the relevant parameters, a linear free energy gap dependence of the rate could be obtained only over a range of 5000-6000 cm(-1) (compared to the experimentally observed range of 10000 cm(-1) reported by Benniston et al.). The present work suggests several extensions/generalizations of the hybrid model which might be necessary to fully understand the observed free energy gap dependence.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry A
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	22 Jul 2009 09:36
Last Modified:	19 Sep 2010 05:28
URI:	http://eprints.iisc.ac.in/id/eprint/19521

Actions (login required)

View Item