Fluorescence decay in aperiodic Frenkel lattices

TL;DR

This paper investigates fluorescence decay in aperiodic Frenkel lattices with self-similar trap arrangements, revealing exponential decay influenced by trap concentration and unique oscillations linked to lattice topology, aiding trap ordering identification.

Contribution

It provides a microscopic analysis of exciton decay in aperiodic lattices and links decay features to lattice topology, offering new insights into trap arrangement effects.

Findings

Decay is exponential and depends on trap concentration and trapping rate.

Small oscillations in decay are characteristic of trap arrangement.

Oscillations relate to the Fourier transform of the lattice topology.

Abstract

We study motion and capture of excitons in self-similar linear systems in which interstitial traps are arranged according to an aperiodic sequence, focusing our attention on Fibonacci and Thue-Morse systems as canonical examples. The decay of the fluorescence intensity following a broadband pulse excitation is evaluated by solving the microscopic equations of motion of the Frenkel exciton problem. We find that the average decay is exponential and depends only on the concentration of traps and the trapping rate. In addition, we observe small-amplitude oscillations coming from the coupling between the low-lying mode and a few high-lying modes through the topology of the lattice. These oscillations are characteristic of each particular arrangement of traps and they are directly related to the Fourier transform of the underlying lattice. Our predictions can be then used to determine experimentally the ordering of traps.