Metal Core Bonding Motifs of Monodisperse Icosahedral Au13 and Larger Au Monolayer-Protected Clusters As Revealed by X-ray Absorption Spectroscopy and Transmission Electron Microscopy

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• 作者：Laurent D. Menard ; Huiping Xu ; Shang-Peng Gao ; Ray D. Twesten ; Amanda S. Harper ; Yang Song ; Gangli Wang ; Alicia D. Douglas ; Judith C. Yang ; Anatoly I. Frenkel ; Royce W. Murray ; Ralph G. Nuzzo
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：August 3, 2006
• 年：2006
• 卷：110
• 期：30
• 页码：14564 - 14573
• 全文大小：424K
• 年卷期：v.110,no.30(August 3, 2006)
• ISSN：1520-5207

文摘

The atomic metal core structures of the subnanometer clusters Au₁₃[PPh₃]₄[S(CH₂)₁₁CH₃]₂Cl₂ (1) and Au₁₃[PPh₃]₄[S(CH₂)₁₁CH₃]₄ (2) were characterized using advanced methods of electron microscopy and X-rayabsorption spectroscopy. The number of gold atoms in the cores of these two clusters was determinedquantitatively using high-angle annular dark field scanning transmission electron microscopy. Multiple-scattering-path analyses of extended X-ray absorption fine structure (EXAFS) spectra suggest that the Aumetal cores of each of these complexes adopt an icosahedral structure with a relaxation of the icosahedralstrain. Data from microscopy and spectroscopy studies extended to larger thiolate-protected gold clustersshowing a broader distribution in nanoparticle core sizes (183 ± 116 Au atoms) reveal a bulklike fcc structure.These results further support a model for the monolayer-protected clusters (MPCs) in which the thiolateligands bond preferentially at 3-fold atomic sites on the nanoparticle surface, establishing an averagecomposition for the MPC of Au₁₈₀[S(CH₂)₁₁CH₃]₄₀. Results from EXAFS measurements of a gold(I)dodecanethiolate polymer are presented that offer an alternative explanation for observations in previousreports that were interpreted as indicating Au MPC structures consisting of a Au core, Au₂S shell, and thiolatemonolayer.