Optical excitations in Sr$_{2}$CuO$_{3}$

TL;DR

This study explores the optical excitation spectra of Sr₂CuO₃, revealing excitonic charge transfer transitions consistent with a one-dimensional extended Hubbard model, and clarifies the nature of observed spectral features.

Contribution

It provides a detailed analysis of optical excitations in Sr₂CuO₃, linking experimental spectra to theoretical models and identifying excitonic charge transfer transitions.

Findings

Identification of a charge transfer transition at 1.8 eV with excitonic character.

Observation of a continuum excitation at 2.7 eV.

Spectral weight sum rule is satisfied within the observed transitions.

Abstract

We investigated excitation spectra of the one-dimensional chain compound Sr$_{2}$CuO$_{3}$. The small peak at 2.3 eV in the loss function was turned to correspond to the strong charge transfer transition at 1.8 eV in conductivity. It has the excitonic character expected in one dimensional extended Hubbard model of the transition from the lower Hubberd band to the Zhang-Rice singlet state. The strongest peak at 2.7 eV in the loss function is attributed to the continuum excitation of the excitonic charge transfer transition. The spectral weight sum rule is satisfied within these transitions.