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

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. Copyright (c) 2005 John Wiley & Sons, Ltd.