Searching for Simple! From Ultrafast Photoelectron Emission Studies of Plasmonic Nanstructures to Thermodynamics/Kinetics of RNA Folding at the Single Molecule Level

February 17, 2017

David J. Nesbitt

Chemists have been amazingly successful with the manipulation of complicated molecular systems, whereas to a physicist, even simple molecules can seem overwhelmingly complex. Physical chemists are blessed (or cursed) with a dual scientific personality. We are attracted to real world chemical systems and yet are often not satisfied posing questions without the requisite rigor to hope for fundamental answers. This talk will provide an overview of work in my labs that attempts to address complex molecular systems but with a physical chemist’s eye toward finding the underlying simplicity. In particular, I will focus on recent results from our labs in the following two areas: 1) Electron oscillation in Au, Ag, and Cu nanostructures (i.e.,  “plasmons”) leads to intense absorption strengths and offers enormous potential for real-world applications in solar energy. We will address how the novel combination of ultrafast OPO lasers, in-vacuo microscopy, and electron photoemission can provide a novel, powerful and remarkably sensitive experimental platform for exploring the fundamental chemical physics and spectroscopy of nanoplasmonic materials. 2) The second topic will be the use of confocal microscopy, fluorescence resonance energy transfer (FRET), and time correlated single photon counting methods to explore the kinetics and thermodynamics of RNA folding at the single molecule level. One issue in particular will be probing the effects of microscopic viscosity and molecular “crowding” on tertiary and secondary structure motifs responsible for “docking” single stranded RNA oligomers into biochemically competent 3D structures. In each area, the focus will be on simple physical pictures that help explain and interpret the underlying chemical physics.