Hot recombination of photogenerated ion pairs

Abstract

The recombination dynamics of ion pairs generated upon electron transfer quenching of perylene in the first singlet excited state by tetracyanoethylene in acetonitrile is quantitatively described by the extended unified theory of photoionization/recombination. The extension incorporates the hot recombination of the ion pair passing through the level-crossing point during its diffusive motion along the reaction coordinate down to the equilibrium state. The ultrafast hot recombination vastly reduces the yield of equilibrated ion pairs subjected to subsequent thermal charge recombination and separation into free ions. The relatively successful fit of the theory to the experimentally measured kinetics of ion accumulation/recombination and free ion yield represents a firm justification of hot recombination of about 90% of primary generated ion pairs.

Investigations of bimolecular photoinduced electron transfer reactions in polar solvents using ultrafast spectroscopy

“…The experimental data could only be reproduced in the intermediate time-range, i.e. between 100 and 700 ps, the stronger disagreement being observed at earlier time [83]. The origin of this discrepancy is still not clear.…”

Direct Femtosecond Observation of Tight and Loose Ion Pairs upon Photoinduced Bimolecular Electron Transfer

“…Then CS always slows down with increasing distance, independent of the magnitude of the driving force. As a consequence, nonMarkovian unified theories of CS and CR, [9,24,25] which take the time dependence of the distribution of distances between the reactants into account, should be refined to include orientational degrees of freedom in V.…”

Charge recombination in excited donor-acceptor complexes with two absorption bands

“…The suggested model was tested numerically using Brownian modeling methods developed in [25,26]; 10 5 random trajectories were used in calculations.…”