Ultrafast carrier phonon dynamics in NaOH-reacted graphite oxide film

TL;DR

This study investigates the ultrafast carrier relaxation dynamics in NaOH-reacted graphite oxide film, revealing two relaxation processes linked to phonon scattering and chemical group coupling, using time-resolved spectroscopy and theoretical calculations.

Contribution

It provides new insights into the ultrafast carrier-phonon interactions in chemically modified graphite oxide, highlighting the role of hydroxyl and -ONa groups.

Findings

Fast relaxation (~0.17ps) due to hydroxyl and -ONa group coupling

Slow relaxation (~2ps) from acoustic phonon scattering

Strong electron-phonon coupling confirmed by calculations

Abstract

NaOH-reacted graphite oxide film was prepared by decomposing epoxy groups in graphite oxide into hydroxyl and -ONa groups with NaOH solution. Ultrafast carrier dynamics of the sample were studied by time-resolved transient differential reflection (\DeltaR/R). The data show two exponential relaxation processes. The slow relaxation process (\sim2ps) is ascribed to low energy acoustic phonon mediated scattering. The electron-phonon coupling and first-principles calculation results demonstrate that - OH and -ONa groups in the sample are strongly coupled. Thus, we attribute the fast relaxation process (\sim0.17ps) to the coupling of hydroxyl and -ONa groups in the sample.