Au144-xCux(SC6H13)60 nanomolecules: effect of Cu incorporation on composition and plasmon-like peak emergence in optical spectra

Au144-xCux(SR)(60) alloy nanomolecules were synthesized and characterized by using ESI-MS to atomic precision. A maximum of 23 copper atoms replace the gold atoms. When the number of copper atoms is higher than eight, a surface plasmon-like peak appears at similar to 520 nm. Based on the fundamental elemental properties of Au and Cu, we predict a mixed atomic ordering and incorporation of Cu atoms into the Au-12 and Au-42 shells of the proposed icosahedral structure model of the 144-atom nanomolecule.