Chemical sensors based on surface plasmon resonance in Si grating structures

The new concept of a Si-based surface plasmon resonance (SPR) sensor has been developed and successfully applied to chemical sensing. The sensitivity to nitrogen dioxide has been estimated at the level of tens of ppb. The Si-based SPR scheme provides an additional surface-enhanced Raman scattering (SERS) channel for data acquisition with spectroscopic selectivity and amplified sensitivity. Using two different SPR methods, the effect of reversible interaction of gold films with ppm concentrations of NO/sub 2/ in air has been observed for the first time. The effect is likely to be associated with the gold film structure on an atomic scale and the nature of NO/sub 2/ as a strong electroactive gas.