Probing Interband Coulomb Interactions in Semiconductor Nanocrystals with 2D Double-Quantum Coherence Spectroscopy

TL;DR

This paper develops a theoretical framework and numerical analysis for 2D double-quantum coherence spectroscopy to investigate interband Coulomb interactions in semiconductor nanocrystals, revealing unique spectroscopic signatures.

Contribution

It introduces a closed set of equations for 2D signals incorporating interband Coulomb interactions and applies them to PbSe nanocrystals, highlighting novel spectroscopic features.

Findings

Identification of unique 2D spectral features linked to interband Coulomb interactions

Numerical simulations for PbSe nanocrystals under different excitation regimes

Development of a theoretical model for exciton-biexciton Coulomb effects

Abstract

Using previously developed exciton scattering model accounting for the interband, i.e., exciton-biexciton, Coulomb interactions in semiconductor nanocrystals (NCs), we derive a closed set of equations for 2D double-quantum coherence signal. The signal depends on the Liouville space pathways which include both the interband scattering processes and the inter- and intraband optical transitions. These processes correspond to the formation of different cross-peaks in the 2D spectra. We further report on our numerical calculations of the 2D signal using reduced level scheme parameterized for PbSe NCs. Two different NC excitation regimes considered and unique spectroscopic features associated with the interband Coulomb interactions are identified.