Polarization-dependent C(<i>K</i>) near-edge x-ray-absorption fine structure of graphite

Rosenberg, R. A.; Love, P. J.; Rehn, Victor

doi:10.1103/physrevb.33.4034

Cited by 296 publications

(195 citation statements)

References 14 publications

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“…8, graphene, 2LG, 3LG and graphite are compared. When the number of layers goes up, peaks G, H and J [42] increase quite strongly and peak C slightly, whereas peak A2 decreases somewhat. These tendencies agree well with experiment [25,26].…”

Section: B Layer Effectsmentioning

confidence: 98%

X-ray absorption spectra of graphene and graphene oxide by full-potential multiple scattering calculations with self-consistent charge density

Krüger

Natoli

et al. 2015

Phys. Rev. B

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X-ray absorption near edge structure (XANES) of graphene, graphene oxide and diamond are studied by the recently developed real-space full potential multiple scattering (FPMS) theory with space-filling cells. It is shown how accurate potentials for FPMS can be generated from self-consistent charge densities obtained with other schemes, especially the projector augmented wave method. Compared to standard multiple scattering calculations in the muffin-tin approximation, FPMS gives much better agreement with experiment. The effects of various structural modifications on the graphene spectra are well reproduced. (1) Stacking of graphene layers increases the peak intensity in the higher energy region. (2) The spectrum of the C atom located at the edge of graphene sheet shows a prominent pre-edge structure. (3) Adsorption of oxygen gives rise to the so-called interlayer-state peak. Moreover, O K-edge spectra of graphene oxide are calculated for three types of bonding, C-OH, C-O-C and C-O, and the proportions of these bondings at 800 • C are deduced by fitting them to the experimental spectrum.

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Section: B Layer Effectsmentioning

confidence: 98%

X-ray absorption spectra of graphene and graphene oxide by full-potential multiple scattering calculations with self-consistent charge density

Krüger

Natoli

et al. 2015

Phys. Rev. B

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“…In order to normalize the C 1s absorption spectra, the images were divided by the x-ray absorption from an area outside the region of interest. All measurements were performed at grazing incidence (16 • ) with a linear polarization almost perpendicular to the basal plane of graphite, a configuration (E c) which enhances transitions into final states of π symmetry [17]. Fig.2 shows C 1s absorption spectra obtained for graphene, bilayer graphene and FLG samples.…”

mentioning

confidence: 99%

“…Moreover, matrix elements strongly depend on polarization. In graphite, the states above the π * resonance have mainly σ symmetry [17].…”

mentioning

confidence: 99%

Near-Edge X-Ray Absorption Fine-Structure Investigation of Graphene

et al. 2008

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We report the near-edge x-ray absorption fine structure (NEXAFS) spectrum of a single layer of graphite (graphene) obtained by micromechanical cleavage of Highly Ordered Pyrolytic Graphite (HOPG) on a SiO2 substrate. We utilized a PhotoEmission Electron Microscope (PEEM) to separately study single-double-and few-layers graphene (FLG) samples. In single-layer graphene we observe a splitting of the π * resonance and a clear signature of the predicted interlayer state. The NEXAFS data illustrate the rapid evolution of the electronic structure with the increased number of layers.The recent discovery of a single sheet of graphite [1], called graphene, has opened up a new area of condensed matter physics.Graphene proves that materials just one atom thick may exist, with exciting prospects for applications. Its unusual electronic spectrum, where charge carriers mimic massless relativistic particles [2,3], also provides an unexpected bridge between condensed matter physics and quantum electrodynamics.The method to obtain single sheets of graphite [1], called micro-mechanical cleavage, allows easy production of sample with a typical size of few tens of microns, ideal for ballistic transport and Quantum Hall effect measurements, but inappropriate for many conventional spectroscopy investigations in Ultra High Vacuum (UHV) conditions. In the absence of new and more efficient ways to make graphene, samples obtained by micro-mechanical cleavage of bulk graphite are used in a limited class of experiments, where the size and the identification of thin flakes is possible. Indeed, after the cleavage with simple adhesive tape, graphene crystallites left on the SiO 2 substrate are extremely rare and hidden amongst hundreds of thicker flakes. Conventional surface science probes of the electronic and structural properties of materials, are then ruled out, unless they are coupled to a microscope. On the other hand, single-and few-layers graphene (FLG) samples have been grown epitaxially by chemical vapour deposition of hydrocarbons on metal substrates [4] and by thermal decomposition of SiC [5]. In both cases, the hybridization of graphene with the substrate is an unavoidable complication, although graphene on SiC preserves most of the electronic properties expected for a free layer [6,7,8].In this Letter we report the near-edge x-ray absorption fine structure (NEXAFS) spectra of a free layer of graphene, and of few-layers graphene (FLG) samples, obtained by a PhotoEmission Electron Microscope (PEEM) in UHV conditions. The spectrum of graphene exhibits a new structure below the π * resonance, reflecting its peculiar density of states (DOS) above the

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“…5 shows photon intensity spectra of BL-13B in the carbon Kedge region before and after in situ carbon removal from the chromium-coated mirror. On the basis of the NEXAFS spectra of graphite (Rosenberg et al, 1986), we ascribed the small negative peak at 285.5 eV in the spectra obtained before the carbon removal to the C 1s ! * transition of graphitelike carbon with a flat-on configuration on the chromiumcoated mirror.…”

Section: In Situ Carbon Removal From Chromium-coated Mirrormentioning

confidence: 99%

In situremoval of carbon contamination from a chromium-coated mirror: ideal optics to suppress higher-order harmonics in the carbonK-edge region

Toyoshima

Kikuchi

Tanaka

et al. 2015

J Synchrotron Radiat

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Carbon-free chromium-coated optics are ideal in the carbonK-edge region (280–330 eV) because the reflectivity of first-order light is larger than that of gold-coated optics while the second-order harmonics (560–660 eV) are significantly suppressed by chromiumL-edge and oxygenK-edge absorption. Here, chromium-, gold- and nickel-coated mirrors have been adopted in the vacuum ultraviolet and soft X-ray branch beamline BL-13B at the Photon Factory in Tsukuba, Japan. Carbon contamination on the chromium-coated mirror was almost completely removed by exposure to oxygen at a pressure of 8 × 10−2 Pa for 1 h under irradiation of non-monochromated synchrotron radiation. The pressure in the chamber recovered to the order of 10−7 Pa within a few hours. The reflectivity of the chromium-coated mirror of the second-order harmonics in the carbonK-edge region (560–660 eV) was found to be a factor of 0.1–0.48 smaller than that of the gold-coated mirror.

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Polarization-dependent C(K) near-edge x-ray-absorption fine structure of graphite

Cited by 296 publications

References 14 publications

X-ray absorption spectra of graphene and graphene oxide by full-potential multiple scattering calculations with self-consistent charge density

X-ray absorption spectra of graphene and graphene oxide by full-potential multiple scattering calculations with self-consistent charge density

Near-Edge X-Ray Absorption Fine-Structure Investigation of Graphene

In situremoval of carbon contamination from a chromium-coated mirror: ideal optics to suppress higher-order harmonics in the carbonK-edge region

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