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- Title
A site-specific comparative study of Au<sub>102</sub> and Au<sub>25</sub> nanoclusters using theoretical EXAFS and l-DOS.
- Authors
Christensen, Stephen L.; Cho, Peter; Chatt, Amares; Zhang, Peng
- Abstract
Recent advances in Au-thiolate nanocluster synthesis have allowed the total structural determination of several nanoclusters by X-ray crystallography. The high-precision structural information of these nanoclusters enables atomic site-specific analysis of local structure and electronic character. In this work, a site-specific comparative study of Au102(SR)44 and Au25(SR)18 was conducted to elucidate the size and site effects on the local environment and electronic character of their common surface structural unit, the -SR-Au-SR-Au-SR- 'double-staple' motif. Simulation of the pseudo-radial distribution function from extended X-ray absorption fine structure (EXAFS) shows a significant difference in their local environments despite their identical geometric shape. Local density of states ( l-DOS) calculations consistently reveal the difference in their electronic characters for gold d-electron density and d-DOS position. These differences are then related to the unique aurophilic interactions and size- or site-dependent electronic character of Au atoms in the double-staple motif. The differing local structure and electronic behaviour of the 'double-staple' motif in Au102(SR)44 and Au25(SR)18 highlight the significance of both size and site effects on the surface structure and electronic property of Au-thiolate nanoclusters. The theoretical results may also be useful in the interpretation of future experimental XAFS and X-ray photoelectron spectroscopy (XPS) data of these nanoclusters.
- Subjects
THIOLATES; GOLD compounds; X-ray crystallography; NANOPARTICLES; NANOSTRUCTURES; EXTENDED X-ray absorption fine structure; ELECTRON density
- Publication
Canadian Journal of Chemistry, 2015, Vol 93, Issue 1, p32
- ISSN
0008-4042
- Publication type
Article
- DOI
10.1139/cjc-2014-0271