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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 of Au38-xAgx(SCH2CH2Ph)24 Alloy Nanomolecules
Chanaka Kumara1, Kevin J Gagnon2, Amala Dass1
1†Department of Chemistry and Biochemistry, University of Mississippi, 322 Coulter Hall, Oxford, Mississippi 38677, United States.
Abstract:
Herein, we report the X-ray crystallographic structure of a 38-metal atom Au-Ag alloy nanomolecule. The structure of monometallic Au38(SR)24 consists of 2 central Au atoms and 21 Au atoms forming a bi-icosahedral core protected by 6 dimeric and 3 monomeric units. In Au38-xAgx(SR)24,where x ranges from 1 to 5, the silver atoms are selectively incorporated into the Au21 bi-icosahedral core. Within the Au21 core, the silver atoms preferentially occupy nine selected locations: (a) the two vertex edges, three atoms on each edge and six atoms total, and (b) the middle face-shared three-atom ring, adding to a total of nine locations. X-ray crystallography yielded a composition of Au34.04Ag3.96(SCH2CH2Ph)24. The crystal structure of the alloy nanomolecule can be described in terms of shells as Au2@Au17.04Ag3.96@ 6×[-SR-Au-SR-Au-SR] 3×[-SR-Au-SR-].
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