Excitonic Strings in one dimensional organic compounds

TL;DR

This paper investigates the existence and properties of excitonic strings in one-dimensional organic compounds using a Hard Core Bosons model, revealing conditions for multi-excitonic states and their transition behaviors.

Contribution

It introduces a theoretical model for excitonic strings in 1D organic systems and analyzes multi-excitonic states with analytical and numerical methods.

Findings

Existence of bi-excitonic, three-excitonic, and n-excitonic strings under certain parameters.

Clarification of transition behaviors from single to bi-excitonic states.

Agreement of analytical results with numerical diagonalizations.

Abstract

Important questions concern the existence of excitonic strings in organic compounds and their signatures in the photophysics of these systems. A model in terms of Hard Core Bosons is proposed to study this problem in one dimension. Mainly the cases with two and three particles are studied for finite and infinite lattices, where analytical results are accessible. It is shown that if bi-excitonic states exist, three-excitonic and even, n-excitonic strings, at least in a certain range of parameters, will exist. Moreover, the behaviour of the transitions from one exciton to the biexciton is fully clarified. The results are in agreement with exact finite cluster diagonalizations of several model Hamiltonians.