Date: Thursday, May 16th
Presenter: Miriam Deutsch, Department of Physics, University of Oregon
In recent years there has been growing interest in harnessing surface-plasmon resonances of nanoscale metal structures to efficiently concentrate electromagnetic fields into sub-wavelength volumes. One of the mainstay model materials for these studies is the rough silver film, favored for its relatively low loss in the visible frequency range as well as its chemical compatibility with many biologically and chemically relevant materials. The intense plasmon fields, localized by disorder in randomly aggregated silver films, have been invaluable in studying surface enhanced Raman scattering, nonlinear optical interactions, and enhanced light emission phenomena. One of the biggest challenges in this field remains the formulation of an accurate theory linking multiscale structure to the observed optical and electronic characteristics in these materials. In this talk I will present results from several studies we conducted using nanostructured silver films, grown as quasi-2D nanoshells on colloidal silica spheres and also as thin films on planar substrates. I will show how the plasmonic resonances of these macroscopic systems are determined by their nanoscale structure, in particular when the metal films are close to the percolation threshold, and discuss our modeling of these phenomena.