MSE Seminar Series: Hans Robinson, Virginia Tech
Localized Surface Plasmon Resonances (LSPR’s) are collective electronic resonances localized at the interface between a metal structure and its surrounding dielectric, and they tend to dominate the optical response of noble metal nanoparticles. LSPR’s have the property that they concentrate light into nm-sized regions, known as hot spots, located in narrow gaps and on sharp corners of the nanostructures. The light intensity in a hot spot can be many orders of magnitude higher than the intensity of the exciting light, making them a suitable for eliciting nonlinear optical (NLO) effects.
In this talk, I will discuss several experiments relating to NLO effects in silver and gold nanoparticles. First, I will discuss generation of second harmonic generation, which have shown can be significantly enhanced by properly combining silver nanotriangles with a polymer with high values of the second order nonlinear optical susceptibility c(2). I will also discuss the observation of plasmonically enhanced multi-photon fluorescence seen in these nanoparticles. Finally, I will discuss our work to use plasmonically enhanced NLO effects to control the assembly of nanoparticles into larger well-ordered constructs. This works by using inducing optically activated chemical reactions at the hot spots, changing the particle surface chemistry locally, enabling assembly akin to the way atoms assemble into larger molecules.
Hans Robinson is Associate Professor of Physics at Virginia Tech, where his research interests are focused the physics and applications of nanooptics, particularly on the optics and photonics of metallic and magnetic nanoparticles and their assemblies. Prof. Robinson obtained his Ph.D. in 2000 from Boston University under the tutelage of prof. Bennett Goldberg. Before Arriving at Virginia Tech in 2005, he was a postdoctoral research associate with the group of prof. Eli Yablonovitch at UCLA.