C K-XANES of graphitic carbons with oxygenated functional groups

Abstract

The X-ray absorption near-edge structure (XANES) in the C K region of graphite oxide (GO) exhibits a complicated and broad profile in the π* (285 eV)-σ* (293 eV) region due to oxygenated carbon atoms. To clarify the oxidation effect on carbon atoms in the spectral profile of GO, we measured the C K-XANES of various oxygenated aromatic compounds and theoretically analyzed them using density function theory (DFT) calculations. From the measured and calculated C K-XANES, the π* peaks of oxygenated carbon atoms shift to the higher-energy range by 0.5-4 eV from 285.5 eV of the typical π* peak of graphite. The energy positions of the shifted π* peaks depend on both the oxygenated functional groups and the molecular structures, confirming that the energy shifts of the π* peaks due to oxygenated carbon atoms cause the broad and complicated peak profiles in the π*-σ* region in C K-XANES of GO.

Keywords: CK-XANES; DFT calculations; Graphite oxide; Soft X-ray absorption.