Plasmonic Aerosols: a novel phase of plasmonic matter

The field of plasmonics has given rise to many innovative optical materials over the years, however these plasmonic materials are limited to only a few phases of matter, either as 2D solids or dilute liquids. Here, we introduce a novel phase of plasmonic matter by aerosolizing gold nanorods into the gas phase from liquid suspensions and simultaneously measure their optical spectra. We show by controlling the aspect ratio of the nanorods that the aerosol absorption peaks are tunable from visible to mid-wave infrared wavelengths. We find for large aspect ratio nanorods extraordinary sensitivity to changes in the refractive index of the host gas (~4,000 nm per refractive index unit). Utilizing this sensitivity dependence, we demonstrate the feasibility to use these plasmonic aerosols as environmental sensors.