Ag-Au-Ag heterometal nanowires: Synthesis, diameter control, and dual transversal modes with diameter dependency

We report on the synthesis of Ag-Au-Ag heterometal nanowires through an epitaxial seed-mediated growth of silver nanowires from gold decahedral seeds. The diameter of the Ag-Au-Ag nanowires is precisely controlled in a range of 60-150 nm by using gold decahedral seeds with corresponding edge sizes. The three transversally excited bulk, localized, and propagating modes exhibit optical signatures in the UV-vis spectra. In particular, the end-on incidence propagating mode is highly sensitive to the nanowire diameter. Such exact control of diameters and diameter-dependent surface plasmon modes are expected to be useful for photonic circuit elements and chemical and biosensors.