Plasma induced enhancements in plasmonic sensitivity of sputter-deposited silver nanoparticles to ethanol vapor

Localized surface plasmon resonances (LSPRs) of silver nanoparticles (Ag NPs) are attractive and useful phenomena for many potential applications. This work employed Ar plasma treatments to modify the LSPR characteristics of Ag NPs for plasmonic sensing applications. A brief plasma exposure eliminated the surface contamination on Ag NPs retaining their morphologies. Ag NPs having such morphologies brought about a broad LSPR spectrum that is unfavorable for plasmonic sensing. Ar plasma exposure for ∼300 s induced Ostwald ripening, isolation and growth of Ag NPs, resulting in a sharp LSPR spectrum. In terms of plasmonic sensing based on the figure of merit, a narrower spectrum with larger peak-shift upon the analyte molecules is required.