Optical absorption in Fibonacci lattices at finite temperature

TL;DR

This paper investigates how Frenkel excitons absorb light in Fibonacci quasiperiodic lattices at finite temperatures, revealing spectral features linked to quasiperiodic order and the potential of excitons as probes of lattice topology.

Contribution

It provides a numerical analysis of exciton absorption spectra in Fibonacci lattices, including effects of thermal vibrations, highlighting observable spectral features at room temperature.

Findings

Satellite absorption lines relate to quasiperiodic order

Spectral features persist at room temperature

Excitons can probe lattice topology despite thermal effects

Abstract

We consider the dynamics of Frenkel excitons on quasiperiodic lattices, focusing our attention on the Fibonacci case as a typical example. We evaluate the absorption spectrum by solving numerically the equation of motion of the Frenkel-exciton problem on the lattice. Besides the main absorption line, satellite lines appear in the high-energy side of the spectra, which we have related to the underlying quasiperiodic order. The influence of lattice vibrations on the absorption line-shape is also considered. We find that the characteristic features of the absorption spectra should be observable even at room temperature. Consequently, we propose that excitons act as a probe of the topology of the lattice even when thermal vibrations reduce their quantum coherence.