Excitons in long molecular chains near the reflecting interface

TL;DR

This paper investigates how reflecting interfaces influence exciton-polariton states in long molecular chains, affecting their decay channels and interactions with surface plasmons and photons, with implications for energy transfer and quenching.

Contribution

It provides a detailed analysis of exciton-surface interactions near reflecting interfaces, highlighting the role of substrate properties and molecular polarization in exciton dynamics.

Findings

Surface plasmons significantly enhance exciton decay into surface excitations.

The interface modifies exciton radiative decay rates depending on polarization and distance.

Dissipative substrates cause additional exciton quenching due to Joule losses.

Abstract

We discuss coherent exciton-polariton states in long molecular chains that are formed due to the interaction of molecular excitations with both vacuum photons and surface excitations of the neighboring reflecting substrate. The resonance coupling with surface plasmons (or surface polaritons) of the substrate can substantially contribute to the retarded intermolecular interactions leading to an efficient channel of the decay of one-dimensional excitons with small momenta via emission of surface excitations. The interface also modifies the radiative decay of excitons into vacuum photons. In an idealized system, excitons with higher momenta would not emit photons nor surface waves. For a dissipative substrate, additional exciton quenching takes place owing to Joule losses as the electric field of the exciton polarization penetrates the substrate. We discuss how these effects depend on the polarization of molecular excitations, their frequency and on the distance of the chain from the substrate.