Plasmon coupling of R6G-linked gold nanoparticle assemblies for surface-enhanced Raman spectroscopy

This paper presents the study of surface-enhanced Raman scattering (SERS) for Rhodamine 6G (R6G)-linked gold (Au) assemblies. The nano-assemblies fabricated with Au nanoparticles, having diameters (D) of ～5–40 nm, possessed interparticle gaps of ～0.03–0.2D, respectively. The R6G-linked Au assemblies displayed weak spectral shifts of localized surface plasmon resonance (LSPR) mode at shorter wavelength region and large fractional red-shifts Δλ ～ 0.07–0.47λ_o at longer wavelength region. The resonant spectral coupling of the nano-assemblies LSPR mode at the longer wavelength region and the optical excitation at ～785 nm, in addition to the highly localized hot spots, could support the large SERS enhancement of R6G-linked Au assemblies.