Enhancement of surface enhanced raman scattering from arrays of hybrid Au–Ag nanoparticles via localised surface plasmon resonance

Abstract

The enhancement of surface enhanced raman scattering of the hybrid Au–Ag triangular nanostructure arrays via localised surface plasmon resonance is systematically investigated. The hybrid nanostructure can prevent the pure silver nanoparticles from oxidation and the stability of Au–Ag nanoparticles compared with non-coated Ag nanoparticles has been verified. Discrete dipole approximation calculated results show the size of the nanoparticle has an important effect on localised surface plasmon resonance of the hybrid nanostructure. Nanosphere lithography is used to fabricate the hybrid nanoparticle arrays with different sizes of nanoparticle. Both theoretical calculations and experimental results show that with an increase in size of the nanoparticle, positions of localised surface plasmon resonance peak are less strongly redshifted and peak of the surface enhanced Raman scattering of the arrays is obviously strengthened. A maximum intensity of the surface enhanced raman scattering can be achieved when the localised surface plasmon resonance wavelength of the hybrid Au–Ag nanoparticle arrays well match the laser excitation wavelength.