Wavelength-Dependent Surface-Enhanced Resonance Raman Scattering by Excitation of a Transverse Localized Surface Plasmon

Abstract

We measured the polarization dependences of surface-enhanced (resonance) Raman scattering (SER(R)S) and localized surface plasmon (LSP) resonance Rayleigh scattering for the same single Ag nanoaggregate to explore whether SER(R)S is dominated by the resonance of incident light with LSPs. We excited the LSPs polarized parallel to the short axis of the Ag nanoaggregate (transverse LSPs) using laser lines from an Ar ion laser (λ = 458, 488, and 514 nm). The polarization dependence of SERRS intensities is opposite to that of the transverse LSPs whose maximum wavelengths are below 500 nm. On the contrary, the polarization dependence of SERS intensities becomes similar to that of the transverse LSPs with the maximum wavelengths above 550 nm. The wavelength-dependent correlation between the transverse LSP and SER(R)S due to the absence and presence of just one junction on the short axis of the Ag aggregate will lead to an accurate understanding of the correlation between LSP and SER(R)S.