OP: Model Theory of Single Nanoparticle Photothermal Absorption Spectroscopy via Optical Microresonators

University Of Washington, Seattle WA

Investigators

Abstract

David J. Masiello of the University of Washington is supported by an award from the Chemical Theory, Models and Computational Methods Program in the Division of Chemistry to develop theoretical and experimental approaches to understand and interpret a new class of single particle photothermal absorption spectroscopy experiments. Photothermal spectroscopy offers a unique platform to measure absorption spectra of single molecules at room temperature and has many potential applications in biology, materials science and other fields. Masiello and his diverse team of undergraduates, graduate students and postdoctoral associates are working to understand how individual nanoscale objects such as single molecules, quantum dots, and plasmonic nanoparticles process light. The light may be absorbed into the particle or it may be scattered. While it is difficult to measure, absorption contains important information about the nano-particle that is not present in the scattering. Masiello's theoretical advances, applied to these new state-of-the-art absorption experiments, allow the experimentalists to distinguish absorption from scattering at the single particle level. They also determine the conditions that are required for other fascinating phenomena such as long-range, nonradiative energy transfer and room-temperature quantum entanglement between distant nanoscale objects in the high quality microresonator cavities that are used in the experiments. Masiello and a colleague have developed and teach a graduate level course on scientific writing aimed at developing and enhancing the scientific communication skills for a diverse group of students. The technical focus of this work is to: 1) develop simple yet rigorous analytical models of the individual and collective electronic excitations in molecules, quantum dots, and metallic nanostructures as well as their interaction with the high-quality optical whispering-gallery modes of their supporting toroidal microresonator cavity; 2) use these models together with full-wave numerical simulations of Maxwell's equations to understand the complex line shapes present in photothermal absorption spectra; and 3) investigate the ability of optical microresonators to assist in the interaction and coherent energy transfer between distant nanoscale objects hybridized or even entangled in ultra-long-range Rydberg-like plasmons.