Exciton Dephasing and Thermal Line Broadening in Molecular Aggregates

TL;DR

This paper models exciton dephasing in molecular aggregates, showing how temperature affects line broadening through phonon interactions, and matches experimental data.

Contribution

It introduces a model incorporating disorder and phonon coupling to explain temperature-dependent line broadening in molecular aggregates.

Findings

Power-law thermal scaling of homogeneous line width.

Excellent agreement with experimental absorption data.

Predicts dephasing behavior considering disorder effects.

Abstract

Using a model of Frenkel excitons coupled to a bath of acoustic phonons in the host medium, we study the temperature dependence of the dephasing rates and homogeneous line width in linear molecular aggregates. The model includes localization by disorder and predicts a power-law thermal scaling of the effective homogeneous line width. The theory gives excellent agreement with temperature dependent absorption and hole-burning experiments on aggregates of the dye pseudoisocyanine.