Core-level spectra from graphene

TL;DR

This paper calculates and analyzes core-level spectra for pristine and doped graphene, revealing characteristic spectral features and their dependence on doping, with results aligning well with experimental data.

Contribution

It provides detailed methods for calculating core-level spectra in graphene and compares theoretical results with experimental data for different doping conditions.

Findings

Pristine graphene shows metallic-like low-energy tailing in spectra.

Doping alters peak shapes in characteristic ways.

Calculated spectra agree well with experimental measurements.

Abstract

We calculate core-level spectra for pristine and doped free-standing graphene sheets. Instructions for how to perform the calculations are given in detail. Although pristine graphene is not metallic the core-level spectrum presents low-energy tailing which is characteristic of metallic systems. The peak shapes vary with doping level in a characteristic way. The spectra are compared to experiments and show good agreement. We compare to two different pristine samples and to one doped sample. The pristine samples are one with quasi-free-standing epitaxial graphene on SiC obtained by hydrogen intercalation and one with a suspended graphene sheet. The doped sample is a gold supported graphene sheet. The gold substrate acts as an acceptor so the graphene sheet gets p-doped.