Fabrication Of Ag Nanorings By Bubble Template Method And Their Plasma Resonance Absorption Properties

In recent years, nanorings have attracted increasing attention due to their unique properties and novel applications in photoelectricity, catalysis and storage. Traditional preparations of nanorings required either rigid experimental conditions, complex procedures or sophisticated equipment. Here a simple and low-cost method has been developed for fabricating Ag nanorings.In the process of our synthesis, steady SiO₂ sol containing silver ion was synthesized firstly. Subsequently, the mixed solution was coated onto substrates by dipping method to form uniform films, and followed by heat-treating at different temperatures. Moreover, the as-prepared samples were characterized by SEM, AFM and XRD, respectively. According to SEM and AFM results, the Ag nanorings have an outer diameter of 200-600 nm and a wall thickness of 50-100nm. Form XRD measurement, the Ag nanorings are face-centered cubic crystal structure. Furthermore, the influences of the experimental conditions (e.g. raw molar ratio of sol, AgNO₃ content, pH value and heat-treating process) on the formation of the nanorings were discussed. In addition, a growth mechanism for Ag nanorings was proposed, based on nanobubble as a template.Plasma resonance absorption properties of the Ag nanorings were studied. The spectral results shows that the surface plasma resonance peak of Ag nanorings occurs atλ= 400nm, which is attributed to characteristic absorption of Ag. As the density of Ag nanorings increases, the plasma resonance absorption enhances. In absorption intensity, the theoretical analysis shows that the experimental results are consistent with spherical optical model calculated results.