Hybrid plasmon damping chemical sensor

The present work demonstrates a novel localized surface plasmon resonance (LSPR) chemical sensor exploiting the mechanism of adsorbate-induced damping of hybrid plasmon resonance. The sensor reports the width (damping factor) and intensity of the hybrid plasmon resonance associated with a monolayer of Ag nanoparticles (AgNPs). These two parameters, continuously acquired from optical extinction spectrum, are substituted in a theoretical relation (derived in the present work) to quantify the number of electrons gained or lost (by the plasmon) due to the adsorbed molecules or atoms. The change in the number of free electrons is proportional to the number of adsorbates. The monolayers of AgNPs have been synthesized by electroless reduction of Ag⁺ on Si thin films on glass. The sensor response has been explored using Hg as the detection agent.