Impurity Quenching of Molecular Excitons. I. Kinetic Comparison of Förster—Dexter and Slowly Quenched Frenkel Excitons in Linear Chains

Abstract: The quenching kinetics of tightly bound excitons for two different one‐dimensional models are compared. The quenching of fully incoherent, or Forster—Dexter, excitons is described by a standard master equation, and that of fully coherent, or Frenkel, excitons by an ad hoc linear differential equation whose eigenvalues are complex. Moments of the chain excitation function (probability that excitation remains at time t) are calculated on each model for finite chains with either localized or uniform initial conditions, free‐end or periodic boundary conditions, one disruptive or one nondisruptive quencher, and various quencher locations, but with only nearest‐neighbor interactions included. The ad hoc equation is treated only in the limit that the quenching is slow enough not to affect the exciton wave functions in first order. In that limit of Frenkel exciton quenching, an analytic expression is given for the mean de‐excitation time in the presence of uniform decay processes such as fluorescence. The master ...