Visual detection of mercury vapor using plasmonic nanoparticle array

The fast and sensitive detections of chemicals adsorption onto solid substrates are of importance to many fields. Ordered arrays of gold nanoparticles with strong surface plasmon resonances allow directly visualized detection of molecular scale adsorptions of mercury vapor on solid substrates. The adsorbed species change local dielectric constants surrounding plasmonic nanoparticles, leading to shifts of plasmon resonance peaks into short wavelength direction because of interactions of chemicals with nanoparticles. The magnitude of peak shifts is proportional to the amount of adsorbed chemicals in certain range, and is sufficiently large so that color changes can be seen directly by naked eyes. The ordered nanoparticles can be made over a large area at high yield, allowing a quantitative, passive, and sensitive detection of molecular species.