Comparison of electron transfer/diffusion models as applied to fluorescence quenching data

Authors:

• Gordon L. Hug,
• Bronisław Marciniak

Abstract

The fluorescence quenching data in solution compiled by Rehm and Weller (Isr. J. Chem. 1970 8, 259) are analyzed systematically. Four different electron-transfer models are applied to the activated reaction step, and two different diffusion schemes are used to account for the transport of the reactants. The data are fit to the equations describing the combined activation/transport mechanisms. Two physical parameters are chosen from each combination for optimization in a nonlinear least-squares procedure. Other physical quantities needed to complete the calculation are estimated, assumed, or taken from measured quantities. The results are discussed and applied to the question of why, for charge-separation reactions in solution, there is an absence of a Marcus inverted region in the regime of high exothermicity in rate constant vs free energy correlations. © 1995 American Chemical Society.