The growth of single-layer graphene on Cu metal by chemical vapor deposition (CVD) is a versatile method to synthesize high-quality, large-area graphene. It is known that high CVD temperatures, close to the Cu melting temperature (1083 ºC), are effective for the growth of large graphene domains, but the growth dynamics of graphene over the high-temperature Cu surface is not clearly understood. Here, we investigated the surface dynamics of the single-layer graphene growth by using heteroepitaxial Cu(111) and Cu(100) films. At relatively lower temperatures, 900~1030 ºC, the as-grown graphene showed the identical orientation with the underlying Cu(111) lattice. However, when the graphene was grown above 1040 ºC a new stable configuration of graphene with 3.4º-rotation became dominant. This slight rotation is interpreted by the enhanced graphene-Cu interaction due to the formation of long-range ordered structure. Further increase of the CVD temperature gave the graphene which is rotated with a wide angle distributions, suggesting the enhanced thermal fluctuation of the Cu lattice. The band structures of CVD graphene grown at different temperatures are well correlated with the observed structural change of the graphene. The strong impact of high CVD temperature on a Cu catalyst was further confirmed by the structural conversion of a Cu(100) film to Cu(111) which occurred during the high temperature CVD process. Our work presents important insight on the growth dynamics of CVD graphene, which can be developed to high quality graphene for future high-performance electronic and photonic devices.

The properties of ceramic materials are strongly influenced by the presence of ultra-dilute impurities or dopants. The near-edge X-ray absorption fine structure (NEXAFS) method by the third-generation synchrotron can be a powerful tool for identifying impurities if a good theoretical tool for interpreting the spectra is provided. We have adopted a novel method to break the bottleneck for its wide application [1]. Local environments of a few 10 ppm levels of Ga in otherwise high-purity MgO ceramic samples were quantitatively examined by NEXAFS and the firstprinciples supercell calculation. Formation of Mg vacancy to compensate the extra charge of substitutional Ga at the Mg site is suggested by the analysis. It is then unambiguously confirmed by the combined study of positron lifetime measurements and plane-wave pseudopotentials calculations. The powerful combination of techniques with NEXAFS to identify the ultra-dilute dopant is fully demonstrated.The experiments were carried out at beamline BL01B1 with a bending magnet system with two mirrors and a fixed-exit double crystal monochromator utilizing Si (311) planes. X-ray fluorescence from the sample was detected by a 19-element Ge solid-state

Near edge X-ray absorption fine structure (NEXAFS) spectra were obtained using total electron yield detection for poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET) and their model compounds 4,4′-biphenyldicarboxylic acid dimethyl ester (PAM), 4,4′-biphenyldicarboxylic acid (PCA), and terephthalic acid (TPA). The spectra of PBT and PET were interpreted with the comparison of the spectral features of model molecules and the polarized NEXAFS spectra of oriented films of PAM, PCA, and PBT. From the polarization dependence, the peaks previously ascribed to a C 1s f π*(ring) or π*(ring/CdO) excitation at 289.8 eV and an O 1s f 3p/Rydberg or f π*(CdO) transition at 536.4 eV were reassigned to a C 1s f σ*(O-CH x ) transition and an O 1s f σ*(O-CH x ) transition, respectively. The present results demonstrate that the polarization dependence of the NEXAFS spectra of oriented small analogous molecules are useful for the assignment of the NEXAFS spectra of polymers.

The valence band structure of rubrene single crystals was experimentally determined by high-resolution angle-resolved and excitation-energy-dependent photoelectron spectroscopy at room temperature. The energy position of the peak derived from the highest occupied molecular orbital did not depend on the excitation energy, reflecting an absence of energy dispersion along the surface normal direction. A two-dimensional valence band dispersion relation over the surface Brillouin zone obtained by angle-resolved photoemission to three critical points was reproduced excellently by a two-dimensional tight binding approximation. Highly anisotropic values of intermolecular transfer integrals to four adjacent molecules were obtained from the present results.

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