Nonequilibrium generalization of F\"{o}rster-Dexter theory for excitation energy transfer

TL;DR

This paper extends F"{o}rster-Dexter energy transfer theory to include short-time nonequilibrium effects caused by nonstationary bath relaxation, providing a new spectral overlap-based rate expression for better experimental and theoretical understanding.

Contribution

It introduces a generalized rate expression accounting for nonequilibrium bath dynamics, bridging a gap in existing energy transfer models.

Findings

Derived explicit rate expression for harmonic oscillator bath model.

Model calculations show dependence of kinetics on coupling strength and temperature.

Discussed relevance to recent experiments and future research directions.

Abstract

F\"{o}rster-Dexter theory for excitation energy transfer is generalized for the account of short time nonequilibrium kinetics due to the nonstationary bath relaxation. The final rate expression is presented as a spectral overlap between the time dependent stimulated emission and the stationary absorption profiles, which allows experimental determination of the time dependent rate. For a harmonic oscillator bath model, an explicit rate expression is derived and model calculations are performed in order to examine the dependence of the nonequilibrium kinetics on the excitation-bath coupling strength and the temperature. Relevance of the present theory with recent experimental findings and possible future theoretical directions are discussed.