(AuAg)(144)(SR)(60) alloy nanomolecules

(Au-Ag)(144)(SR)(60) alloy nanomolecules were synthesized and characterized by ESI mass spectrometry to atomic precision. The number of Ag atoms can be varied by changing the incoming metal ratio and plateaus at similar to 60. UV-vis data demonstrates that the electronic structure of the nanomolecules can be tuned by incorporation of silver atoms. Based on the proposed 3-shell structure of Au-144(SR)(60), we hypothesize that the Ag atoms are selectively incorporated in to the symmetry equivalent 60-atom shell-having Au-12, Au-42, Ag-60 concentric shells with 30-SR-Au-SR-protecting units.