International Journal of Photoenergy 
Volume 2008 (2008), Article ID 150682, 8 pages
doi:10.1155/2008/150682
Research Article

Two-Dimensional Free Energy Surfaces for Electron Transfer Reactions in Solution

Shigeo Murata,1 Maged El-Kemary,2 and M. Tachiya1

 1National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan
2Chemistry Department, Faculty of Education, Kafr ElSheikh University, Kafr ElSheikh 33516, Egypt
Received 2 May 2008; Revised 18 June 2008; Accepted 18 August 2008

Recommended by Mohamed Sabry Abdel-Mottaleb

Abstract

Change in intermolecular distance between electron donor (D) and acceptor (A) can induce intermolecular electron transfer (ET) even in nonpolar solvent, where solvent orientational polarization is absent. This was shown by making simple calculations of the energies of the initial and final states of ET. In the case of polar solvent, the free energies are functions of both D-A distance and solvent orientational polarization. On the basis of 2-dimensional free energy surfaces, the relation of Marcus ET and exciplex formation is discussed. The transient effect in fluorescence quenching was measured for several D-A pairs in a nonpolar solvent. The results were analyzed by assuming a distance dependence of the ET rate that is consistent with the above model.