Plasmonic responses of Cu–Ag bimetallic system: Influence of distinctiveness and arrangements

Abstract

In this article, the effect of the distinctiveness and arrangements on the plasmonic resonance of Cu–Ag system were studied by finite element method, and the effect of morphologies on the plasmonic properties of Cu@Ag core@shell NPs and Cu–Ag corn-cob liked NPs was investigated by experiment. For Cu@Ag core-shell structure, as the fixed thickness of Ag-shell at 10 nm, the dipole plasmon resonance gradually blue-shifts with increasing the radius of Cu core, and as the fixed radius of Cu-core at 50 nm, the feature peak shows a red-shift and broadening with increasing the thickness of Ag shell. For Cu–Ag corn-cob structure, the feature for different Ag coverage are similar to each other and most of the them follow the blue-shifted tendency with the increase the degree of Ag-coverage. Furthermore, as the regular-shaped structure increases (form trigonal to spherical), the plasmon resonance gradually blue shifts, and finally, we use two parameters to describe the different idealized Cu–Ag structure: separation, exterior contact, intersection and core@shell. The combined information from our simulation and experiment will give guidelines for choosing adequate particles when aiming at certain plasmonic properties.