Magnetoplasmonic Nanomaterials: A Route to Predictive Photocatalytic, Light-Harvesting and Ferrofluidic Properties

Abstract

Abstract : Nanostructured materials offer great potential for utilization, storage, and transport of energy over much of the solar spectrum. These unique opportunities arise because nanomaterials often display strikingly different chemical and physical properties than their bulk counterparts. Under AFOSR support, my research group has provided structure-specific descriptions of the optical and electronic properties of nanoscale materials via the development and utilization of advanced spectroscopy techniques. Our advances encompass three main areas: 1) spectroscopy and applications of plasmon-supporting metal nanostructures, 2) optical properties of light-harvesting nanoparticle networks, and 3) development of new laser-based measurement techniques. My group developed and used femtosecond plasmon resonance spectroscopy to study coherent electron dynamics in noble metal nanoparticles. We extensively studied hollow, fluid-filled gold nanospheres (HGN). Interest in these structures is multifold, but it stems primarily from size-dependent contributions to the localized surface plasmon resonance (LSPR) spectral position and line width. We found that the hollow morphology increases LSPR sensitivity to the surroundings. We are currently using this effect to study molecular dynamics at nanoparticle surfaces and in confined, nanoscale volumes. We also described inter-particle electromagnetic coupling effects in plasmonic nanoparticle networks. We developed new single-particle nonlinear optical (NLO) spectroscopy methods and published the first report of an aggregation-induced blue shift of a nanosphere's LSPR. Until this time, it was believed that nanosphere aggregation resulted in an LSPR red shift. As a result of our work, several theoretical and experimental groups have become interested in describing and using this unique phenomenon, which impacts many applications. We published our findings in JACS in 2010, and this paper has already been cited 20 times.