Phonon-Induced Transparency in Functionalized Single Layer Graphene

TL;DR

This paper demonstrates phonon-induced transparency in functionalized graphene through infrared spectroscopy, revealing asymmetric antiresonances linked to phonon modes and chemical potential, supported by a new scattering model and simulations.

Contribution

It introduces a novel model explaining phonon-induced transparency in graphene, supported by experimental measurements and numerical simulations.

Findings

Observation of asymmetric transparency windows at phonon energies

Anti-resonances vary with chemical potential

Model involving coherent intraband scattering explains the phenomena

Abstract

Herein, intervalley scattering is exploited to account for anomalous antiresonances in the infrared spectra of doped and disordered single layer graphene. We present infrared spectroscopy measurements of graphene grafted with iodophenyl moieties in both reflection microscopy and transmission configurations. Asymmetric transparency windows at energies corresponding to phonon modes near the {\Gamma} and K points are observed, in contrast to the featureless spectrum of pristine graphene. These asymmetric antiresonances are demonstrated to vary as a function of the chemical potential. We propose a model which involves coherent intraband scattering with defects and phonons, thus relaxing the optical selection rule forbidding access to ${\bf q} \neq$ {\Gamma} phonons. This interpretation of the new phenomenon is supported by our numerical simulations that reproduce the experimental features.