TY - JOUR A1 - Ehlert, Christopher A1 - Unger, Wolfgang A1 - Saalfrank, P. T1 - C K-edge NEXAFS spectra of graphene with physical and chemical defects: a study based on density functional theory T2 - Physical chemistry, chemical physics N2 - Recently, C K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of graphite (HOPG) surfaces have been measured for the pristine material, and for HOPG treated with either bromine or krypton plasmas (Lippitz et al., Surf. Sci., 2013, 611, L1). Changes of the NEXAFS spectra characteristic for physical (krypton) and/or chemical/physical modifications of the surface (bromine) upon plasma treatment were observed. Their molecular origin, however, remained elusive. In this work we study by density functional theory, the effects of selected point and line defects as well as chemical modifications on NEXAFS carbon K-edge spectra of single graphene layers. For Br-treated surfaces, also Br 3d X-ray Photoelectron Spectra (XPS) are simulated by a cluster approach, to identify possible chemical modifications. We observe that some of the defects related to plasma treatment lead to characteristic changes of NEXAFS spectra, similar to those in experiment. Theory provides possible microscopic origins for these changes. PB - The Royal Soc. of Chemistry CY - Cambridge KW - Graphene KW - NEXAFS KW - Spectrum simulation KW - Density functional theory PY - 2014 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/30965 AN - OPUS4-30965 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-309658 SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 27 SP - 14083 EP - 14095 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany