Anisotropy of Chemical Bonding in Semifluorinated Graphite C2F Revealed with Angle-Resolved X-ray Absorption Spectroscopy

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• 作者：Alexander V. Okotrub ; Nikolay F. Yudanov ; Igor P. Asanov ; Denis V. Vyalikh ; Lyubov G. Bulusheva
• 刊名：ACS Nano
• 出版年：2013
• 出版时间：January 22, 2013
• 年：2013
• 卷：7
• 期：1
• 页码：65-74
• 全文大小：666K
• 年卷期：v.7,no.1(January 22, 2013)
• ISSN：1936-086X

文摘

Highly oriented pyrolytic graphite characterized by a low misorientation of crystallites is fluorinated using a gaseous mixture of BrF₃ with Br₂ at room temperature. The golden-colored product, easily delaminating into micrometer-size transparent flakes, is an intercalation compound where Br₂ molecules are hosted between fluorinated graphene layers of approximate C₂F composition. To unravel the chemical bonding in semifluorinated graphite, we apply angle-resolved near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and quantum-chemical modeling. The strong angular dependence of the CK and FK edge NEXAFS spectra on the incident radiation indicates that room-temperature-produced graphite fluoride is a highly anisotropic material, where half of the carbon atoms are covalently bonded with fluorine, while the rest of the carbon atoms preserve 蟺 electrons. Comparison of the experimental CK edge spectrum with theoretical spectra plotted for C₂F models reveals that fluorine atoms are more likely to form chains. This conclusion agrees with the atomic force microscopy observation of a chain-like pattern on the surface of graphite fluoride layers.

Keywords:

layered materials; fluorination; graphene; X-ray absorption; DFT calculation