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Updated: Apr 5, 2026

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles
Published on: July 5, 2016
X-ray Crystal Structure and Theoretical Analysis of Au25-xAgx(SCH2CH2Ph)18(-) Alloy
Chanaka Kumara1, Christine M Aikens2, Amala Dass1
1†Department of Chemistry and Biochemistry, University of Mississippi, Oxford, Mississippi 38677, United States.
Abstract:
The atomic arrangement of Au and Ag atoms in Au25-xAgx(SR)18 was determined by X-ray crystallography. Ag atoms were selectively incorporated in the 12 vertices of the icosahedral core. The central atom and the metal atoms in the six [-SR-Au-SR-Au-SR-] units were exclusively gold, with 100% Au occupancy. The composition of the crystals determined by X-ray crystallography was Au18.3Ag6.7(SCH2CH2Ph)18. This composition is in reasonable agreement with the composition Au18.8Ag6.2(SCH2CH2Ph)18 measured by electrospray mass spectrometry. The structure can be described in terms of shells as Au1@Au5.3Ag6.7@6×[-SR-Au-SR-Au-SR-]. Density functional theory calculations show that the electronic structure and optical absorption spectra are sensitive to the silver atom arrangement within the nanocluster.
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