Summary: J. Phys. Chem. 1995,99, 5389-5401 5389
Equilibration in Reversible Bimolecular Reactions
Arieh L. Edelstein and Noam Agmon*
Department of Physical Chemistry and the Fritz Haber Research Center, The Hebrew University,
Jerusalem 91904, Israel
Received: November 8, 1994; In Final Form: January 26, 1995@
Fast reversible pseudo-unimolecular reactions do not approach equilibrium in the simple exponential fashion
predicted by chemical rate equations. Many-body effects in bimolecular reactions have been revealed in an
extensive series of Brownian simulations, showing up to three distinct phases in the approach to equilibrium.
Recent theoretical developments are compared with the simulation as well as with experimental data concerning
the pH effect in excited-state proton transfer to solvent.
I. Introduction and Overview
How do the concentrations of chemical species undergoing
a reversible chemical reaction in solution reach equilibrium?
The traditional theory of diffusion-influenced reactions does
not address this question, as it focuses on irreversible reactions.
Chemical rate equations* predict that elementary pseudo-
may agree with experimental data of slow, "rate-limited"
reactions. For fast reactions this is not the case.