Microscopic view on the ultrafast photoluminescence from photo-excited graphene

TL;DR

This paper combines theory and experiments to explore ultrafast photoluminescence in graphene, revealing both incoherent and coherent mechanisms, with the latter showing a spectral shift confirmed experimentally for the first time.

Contribution

It introduces a microscopic theory identifying a coherent photoluminescence component and demonstrates its spectral shift through pioneering experiments.

Findings

Identification of a coherent photoluminescence component

Spectral shift of the coherent emission with excitation energy

Experimental confirmation of the theoretical prediction

Abstract

We present a joint theory-experiment study on ultrafast photoluminescence from photoexcited graphene. Based on a microscopic theory, we reveal two distinct mechanisms behind the occurring photoluminescence: Besides the well-known incoherent contribution driven by non-equilibrium carrier occupations, we found a coherent part that spectrally shifts with the excitation energy. In our experiments, we demonstrate for the first time the predicted appearance and spectral shift of the coherent photoluminescence.