Surface‐enhanced Raman scattering from oxazine 720 adsorbed on scratched gold films

Abstract

Surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) from oxazine 720 (oxa) dye adsorbed on scratched gold films are reported. The SERS-active surface was prepared by performing a series of scratches in a 100 nm thick gold film deposited in glass. Atomic force microscopic imaging revealed a sub-structure within the scratches containing a set of parallel gold wires of different sizes and shapes. The 1-D order imposed by the parallelism between these wires is responsible for an interesting polarization effect observed in forward scattering experiments. It is shown that the maximum enhanced signal is observed when the polarization of the incident field is perpendicular to the direction of the scratches. This polarization discrimination may be useful in the design of SERS applications in chemical sensing and optical switching. Moreover, we also show that these scratched gold surfaces can be used as ordinary SERS substrates for experiments in backscattering using a common Raman microscope in non-resonance conditions with the excitation energy. This was accomplished by obtaining the electrochemical SERS of oxa in situ (under electrochemical control). The potential dependence of the SERS from oxa adsorbed on scratched Au is compared with previous results obtained with Ag electrodes.

The Use of Polarization-dependent SERS from Scratched Gold Films to Selectively Eliminate Solution-phase Interference

“…These slides were scratched by running a 10μm metal tip along the surface of the gold. AFM images of scratches produced in this way are published elsewhere [16,17]. They show that a set of parallel gold nanowires, with a random distribution of sizes and shapes, are formed within the scratches.…”

“…It has already been demonstrated that, for molecules adsorbed onto a scratched gold surface, SERS intensity is dependent upon the direction of incident-beam linear polarization relative to the scratches [16,17]. This phenomenon is not unique to scratched gold surfaces but may be found wherever a SERS substrate has linear features.…”

Reproducible SERRS from structured gold surfaces

“…Over the last decade researchers have focused on discovering and improving methods for fabricating reproducible substrates for SER(R)S. Amongst these, vapourdeposited silver films 17 and silver colloids 18 have been the most heavily researched. There are relatively few reports 12,19 of SERRS on gold substrates. Nevertheless, gold is attractive as a substrate because, although the surface enhancements are B10 times lower than for comparable silver surfaces, gold surfaces are more stable than their silver counterparts.…”

Plasmonic Resonance Excited Extinction Spectra of Cross-Shaped Ag Nanoparticles

“…Recently, the study of the plasmonic properties of noble metal nanoparticles have attracted much attention by researchers because of their potential applications of being used as components in a diverse range of technologies such as waveguides [1], photonic circuits [2], molecular rules [3], chemical/biological sensors [4,5], and surfaceenhanced Raman scattering (SERS) [6,7]. All of these applications were carried out based on localized surface plasmon resonance (LSPR) of the nanoparticle.…”