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Characterization of F + ‐irradiated graphite surfaces using photon‐stimulated desorption spectroscopy
Author(s) -
Sekiguchi Tetsuhiro,
Baba Yuji,
Shimoyama Iwao,
Nath Krishna G.
Publication year - 2006
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.2172
Subject(s) - xanes , spectroscopy , desorption , analytical chemistry (journal) , chemistry , spectral line , extended x ray absorption fine structure , absorption spectroscopy , irradiation , ion , materials science , optics , physics , adsorption , organic chemistry , quantum mechanics , chromatography , astronomy , nuclear physics
Abstract We investigated nature of the orientation in the topmost layers of F + ‐irradiated graphite using polarization‐dependent near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy, incorporating partial electron‐yield (PEY) detection and photon‐stimulated ion desorption (PSID) techniques. The fluorine K‐edge NEXAFS spectra conducted in PEY mode showed no significant dependence on polarization angles. In contrast, NEXAFS spectra recorded in F + ion yield mode showed enhanced yields at a feature of ∼689.4 eV, assigned as a σ*(CF) state relevant to CF sites: furthermore, the yields depended on polarization angles. The F + ion yields at the feature are larger in normal incidence than in grazing incidence, suggesting that the CF bonds prefer a relatively downward tilt at the topmost layer, while being randomly directed at deeper regions. We conclude that the difference in the orientation structures between the surface and the bulk is reflected in the NEXAFS spectra recorded in the two different detection modes. It was also found that H + ‐ and F 2+ ‐PSID NEXAFS spectra are helpful in understanding the desorption mechanisms, and thus in analysing NEXAFS data. Copyright © 2006 John Wiley & Sons, Ltd.