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Advances in Physical Chemistry
Volume 2012 (2012), Article ID 962594, 7 pages
http://dx.doi.org/10.1155/2012/962594
Research Article

Fluorescence Quenching by Reversible Charge Separation Followed by Ions Recombination and Their Separation Suppressed by Coulomb Attraction

1Chemical Physics Department, Weizmann Institute of Science, Rehovot 76100, Israel
2Institute of Chemical Kinetics and Combustion, RAN, Novosibirsk 630090, Russia

Received 9 April 2012; Accepted 17 June 2012

Academic Editor: Chaoyuan Zhu

Copyright © 2012 A. I. Burshtein and A. B. Doktorov. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The Stern-Volmer constant is specified for the luminescence quenched by reversible ionization of excited molecules. The exergonic branch of the Rehm-Weller free energy dependence of this constant is known to be a plateau determined by irreversible ionization being under diffusion control. In the endergonic region the ionization is reversible and competes with the irreversible in-cage recombination of ions and their escape from the cage. At strong Coulomb attraction the latter phenomenon is shown to be negligible compared to the former that determines the shape and location of the descending branch of the Rehm-Weller curve. At weaker Coulomb attraction (at higher solvent polarity), this curve turns down at larger endergonicity. The experimental data obtained in solvents of different polarities are put in order and in full accordance with present theory.