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The structure of the Au(111)/methylthiolate interface : new insights from near-edge X-ray absorption spectroscopy and X-ray standing waves
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Chaudhuri, Anindita, Odelius, Michael, Jones, R. G., Lee, Tien-Lin, Detlefs, B. and Woodruff, D. P. (2009) The structure of the Au(111)/methylthiolate interface : new insights from near-edge X-ray absorption spectroscopy and X-ray standing waves. Journal of Chemical Physics, Vol.130 (No.12). p. 4708. doi:10.1063/1.3102095 ISSN 0021-9606.
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Official URL: http://dx.doi.org/10.1063/1.3102095
Abstract
The local structure of the Au(111)([square root of]3×[square root of]3)R30°-methylthiolate surface phase has been investigated by S K-edge near-edge s-ray absorption fine structure (NEXAFS) both experimentally and theoretically and by experimental normal-incidence x-ray standing waves (NIXSW) at both the C and S atomic sites. NEXAFS shows not only excitation into the intramolecular sigma* S–C resonance but also into a sigma* S–Au orbital perpendicular to the surface, clearly identifying the local S headgroup site as atop a Au atom. Simulations show that it is not possible, however, to distinguish between the two possible adatom reconstruction models; a single thiolate species atop a hollow-site Au adatom or a dithiolate moiety comprising two thiolate species bonded to a bridge-bonded Au adatom. Within this dithiolate moiety a second sigma* S–Au orbital that lies near parallel to the surface has a higher energy that overlaps that of the sigma* S–C resonance. The new NIXSW data show the S–C bond to be tilted by 61° relative to the surface normal, with a preferred azimuthal orientation in <211>, corresponding to the intermolecular nearest-neighbor directions. This azimuthal orientation is consistent with the thiolate being atop a hollow-site Au adatom, but not consistent with the originally proposed Au-adatom-dithiolate moiety. However, internal conformational changes within this species could, perhaps, render this model also consistent with the experimental data.
Item Type: | Journal Article | ||||
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Subjects: | Q Science > QC Physics | ||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||
Library of Congress Subject Headings (LCSH): | Adsorption -- Research, Binding sites (Biochemistry), Self-assembly (Chemistry) -- Research, Thin films, Multilayered, X-ray absorption near edge structure | ||||
Journal or Publication Title: | Journal of Chemical Physics | ||||
Publisher: | American Institute of Physics | ||||
ISSN: | 0021-9606 | ||||
Official Date: | 26 March 2009 | ||||
Dates: |
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Volume: | Vol.130 | ||||
Number: | No.12 | ||||
Page Range: | p. 4708 | ||||
DOI: | 10.1063/1.3102095 | ||||
Status: | Peer Reviewed | ||||
Access rights to Published version: | Open Access (Creative Commons) | ||||
Funder: | European Synchrotron Radiation Facility (ESRF) |
Data sourced from Thomson Reuters' Web of Knowledge
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