To elucidate the possibility of quantitatively analyzing sp 2-hybridized carbon (sp 2-C) and sp 3-C in carbon materials using total-electronyield (TEY) X-ray absorption spectra (XAS) in the C K region, we measured the TEY-XAS of mixtures of multi-walled carbon nanotubes or carbon black as sp 2-C sources and diamond as an sp 3-C source. The measured relationship between the à = à peak intensity ratio in the C K TEY-XAS and the weight (atomic)% of sp 2-C can be successfully explained by the summed TEY of the sp 2-C and sp 3-C components and considering the TEY efficiency of sp 3-C relative to sp 2-C, k. However, the experimentally determined k values show that TEY of the sp 3-C is much smaller than that of sp 2-C by about one order of magnitude, even depending on the chemical form and/or electronic properties of individual carbon components. This suggests that further evaluation of the TEY efficiency is necessary prior to the quantitative sp 2 /sp 3 analysis of carbon materials using the TEY-XAS.
ABSTRACT:We used the discrete variational (DV) -X␣ method to analyze the highresolution soft X-ray emission and absorption spectra in the CK region of titanium carbide (TiC). The spectral profiles of the X-ray emission and absorption can be successfully reproduced by the occupied and unoccupied density of states (DOS), respectively, in the C2p orbitals of the center carbon atoms in a Ti 62 C 63 cluster model, suggesting that the center carbon atom in a large cluster model expanded to the cubic-structured 5 3 (ϭ 125) atoms provides sufficient DOS for the X-ray spectral analysis of rock-salt structured metal carbides.
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