Surface Plasmon Resonance from Bimetallic Interface in Au–Ag Core–Shell Structure Nanowires

Jian Zhu

doi:10.1007/s11671-009-9344-4

Abstract

Transverse surface plasmon resonances (SPR) in Au–Ag and Ag–Au core–shell structure nanowires have been investigated by means of quasi-static theory. There are two kinds of SPR bands resulting from the outer surface of wall metal and the interface between core and wall metals, respectively. The SPR corresponding to the interface, which is similar to that of alloy particle, decreases and shifts obviously with increasing the wall thickness. However, the SPR corresponding to the outer surface, which is similar to that of pure metal particle, increases and shifts slightly with increasing the wall thickness. A mechanism based on oscillatory surface electrons under coulombic attraction is developed to illuminate the shift fashion of SPR from bimetallic core–shell interface. The net charges and extra coulombic force in metallic wall affect the SPR energy and the shift fashion.

Highlights

The optical properties of bimetallic Au–Ag nanoparticles are currently of considerable interest and the subject of a significant literature due to the potential uses of the tunable light absorption, scattering and local field enhancement in the UV-visible region [1, 2]
We propose to investigate the origin of the surface plasmon resonances (SPR) at the interface of Au–Ag core–shell structure bimetallic nanowire by calculating the wall thickness dependent absorption spectra
One is resulted from the outer surface of wall metal and is similar to that of pure metallic particle, the other is resulted from the interface between the core and wall metals and is similar to that of alloy particle

Summary

Introduction

The optical properties of bimetallic Au–Ag nanoparticles are currently of considerable interest and the subject of a significant literature due to the potential uses of the tunable light absorption, scattering and local field enhancement in the UV-visible region [1, 2]. Keywords Surface plasmon resonance (SPR) Á Interface Á Bimetallic Á Core–shell structure Á Nanowires The composition or shell thickness dependent surface plasmon resonance (SPR) absorption spectra of both core–shell type and alloy model Au–Ag nanoparticles have already been studied experimentally and theoretically [3,4,5,6].

Results

Conclusion