SILICON-BASED SURFACE-PLASMON RESONANCE COMBINED WITH SURFACE-ENHANCED RAMAN-SCATTERING FOR CHEMICAL SENSING

A Si-based surface plasmon resonance (SPR) technique has been successf ully applied to NO2 sensing at ppm level, with estimated detectability at less than 100 ppb. Surface-enhanced Raman scattering (SERS) has be en used in this scheme as an inherent additional data acquisition chan nel capable of providing spectroscopic selectivity and amplified sensi tivity. The behavior of both the SERS spectrum and the SPR-induced pho tosignal produced by Au-on-Si grating structures coated with thin 18-c rown-6 metal-free phthalocyanine films was simultaneously recorded for exposure of the films to 10 ppm of NO2 in air and its reversal in cle an air. Both responses have been found to be reversible. The combinati on of Si-based SPR and SERS looks promising for thin-film and surface explorations, both in fundamental and sensor applications. (C) 1997 Am erican Institute of Physics.