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
The atomic metal core structures of the subnanometer clusters Au{sub 13}[PPh{sub 3}]{sub 4}[S(CH{sub 2}){sub 11}CH{sub 3}]{sub 2}Cl{sub 2} and Au{sub 13}[PPh{sub 3}]{sub 4}[S(CH{sub 2}){sub 11}CH{sub 3}]{sub 4} were characterized using advanced methods of electron microscopy and X-ray absorption spectroscopy. The number of gold atoms in the cores of these two clusters was determined quantitatively 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 Au metal cores of each of these complexes adopt an icosahedral structure with a relaxation of the icosahedral strain. Data from microscopy and spectroscopy studies extended to larger thiolate-protected gold clusters showing 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 thiolate ligands bond preferentially at 3-fold atomic sites on the nanoparticle surface, establishing an average composition for the MPC of Au{sub 180}[S(CH{sub 2}){sub 11}CH{sub 3}]{sub 40}. Results from EXAFS measurements of a gold(I) dodecanethiolate polymer are presented that offer an alternative explanation for observations in previous reports that were interpreted as indicating Au MPC structures consisting of a Au core, Au2S shell, and thiolate monolayer.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 914163
- Report Number(s):
- BNL-78731-2007-JA; JPCBFK; TRN: US200804%%320
- Journal Information:
- J. Phys. Chem. B, Vol. 110; ISSN 1089-5647
- Country of Publication:
- United States
- Language:
- English
Similar Records
Beyond the staple motif: a new order at the thiolate–gold interface
Geometry and Charge State of Mixed-Ligand Au13 Nanoclusters