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Mane, J.M., Le Normand, F., Medjo, R.E., Cojocaru, C.S., Ersen, O., Senger, A., Laffon, C., Sendja, B.T., Biouele, C.M., Ben-Bolie, G.H., Ateba, P.O. and Parent, P. (2014) Alignment of Vertically Grown Carbon Nanostructures Studied by X-Ray Absorption Spectroscopy. Materials Sciences and Applications, 5, 966-983.
http://dx.doi.org/10.4236/msa.2014.513098

has been cited by the following article:

• TITLE: Theoretical Investigation of X-Ray Absorption near Edge Spectroscopy (XANES) Angular Dependence of Aligned Carbon Nanotubes Grown by DC HF CVD Process

  AUTHORS: Bridinette Thiodjio Sendja, Rolant Eba Medjo, Jeannot Mane Mane, Germain Hubert Ben-Bolie, Pierre Owono Ateba

  KEYWORDS: Angular Dependence, XANES, Normal Incidence, Grazing Incidence, Carbon Nanotubes, Intensity

  JOURNAL NAME: Materials Sciences and Applications, Vol.6 No.5, May 12, 2015

  ABSTRACT: Carbon nanotubes (CNTs) grown on plain substrates SiO2/Si(100) by a direct current and hot filaments catalytic chemical vapor deposition process have been studied by synchrotron X-ray absorption near edge spectroscopy (XANES) technique to theoretically investigate the angular-dependence of carbone (C) K-edge π* and σ* transitions. Experimental XANES spectra show that π* resonance increases with the incidence angle from normal to grazing incidence angle while σ* resonance decreases. This has been explained by the sine-square and cosine-square dependencies of π* and σ* intensities, respectively. These results were confirmed by theoretical XANES curves of highly oriented pyrolytic graphite (HOPG) and CNTs plotted versus incidence angle. It has been shown that π* and σ* transitions strongly depend on the nature of polarized light (linearly or circularly). At the linear polarized light, π* resonance is a preference as well as at right-circular polarized. At the left-circular polarized light, σ* resonance is a preference. The π* intensities are high at parallel orientation and the σ* intensities are low at normal orientation. The smallest π* intensity is noticed at normal orientation, where the π* orbitals are supposed to be lying parallel to the surface plane for perfectly aligned HOPG or CNTs. This explains the incomplete extinction of π* intensity. We noticed at parallel orientation a region where any π* and σ* transitions did not expect because of the lack of polarization light.