Surface enhanced Raman spectroscopy (SERS) sensors for gas analysis

Abstract

This paper presents work towards a gas sensor based on surface enhanced Raman spectroscopy (SERS). Sensitive SERS analysis of CO and N₂O was performed using a mixed AgPd nanoparticle substrate that facilitated effective gas adsorption and strong SERS generation. The adsorption, desorption and displacement of both gases from the AgPd substrate were studied. We find that heating/cooling of the AgPd is necessary for CO adsorption but after this step a maximum SERS enhancement factor (EF) of 4 × 10⁵ was measured and subsequent desorption and displacement occurred readily. For N₂O, adsorption occurred at ambient temperature and the maximum SERS EF was 1 × 10⁵, but desorption required heating and CO would not displace N₂O from the surface but was rather co-adsorbed. We conclude that it is necessary to ensure analytes adsorb relatively weakly to the SERS substrate to enable continuous, real-time analysis of multiple analytes and to avoid substrate contamination.