Research Interests

Laser Spectroscopy, Quantum Solvation, Reaction Dynamics, Kinetics, Pulsed IR Laser Spectroscopy, and Molecular Beams
 

A fundamentally important pursuit in chemistry is that of understanding the detailed dynamical processes involved in the breaking and forming of chemical bonds. Such an understanding is highly elusive when the reaction takes place in a solvent.

Topics that are central to chemical change - particularly, reaction dynamics of atmospheric and combustion related radicals, the role of intermolecular forces in reactions, and the utilization of lasers to control or influence reaction mechanisms. Chemical reactions in macroscopic quantum systems – chemistry in a new kind of beaker! This includes radical and molecular ion reactions in liquid He and solid para-H2, quantum dynamics in confined systems, and low-temperature condensed phase reactions. Develop new experimental tools - such as infrared lasers, infrared spectroscopic techniques, and clean, high-flux, low-temperature sources of reactive species (radicals and molecular ions).

Efforts in our group are currently focused on studying chemical reaction dynamics in special types of condensed phases. Ongoing work is looking at vibrationally driven reactions of radicals in solid para-hydrogen (see figure below, each large blue ball represents H2). This form of molecular hydrogen, where all the nuclear spins are paired, is called para-hydrogen and under atmospheric pressure it forms a crystalline solid at T < 10 K. However, because of the weak intermolecular forces and the exceedingly light mass of H2, solid hydrogen is a quantum solid with very special properties. Recent experimental advances have made it possible to dope this quantum solid with molecular radical species.

The cold temperature of the quantum solid prevents thermal reaction of the radical with the H2, but laser excitation of specific vibrational motions can be used to trigger reaction. An understanding of these types of vibrationally driven reactions is necessary if we are to develop advanced rockets fuels (liquid hydrogen is still the best) and in the utilization of H2 as a green fuel for combustion (fuel cells and H2 storage). Not to mention that the remarkable properties of quantum solids like para-hydrogen make it possible to: synthesize metastable molecular structures, form radical-molecule complexes, slow reaction rates on barrierless potentials by orders of magnitude, exploit unique transport phenomena, and create bubbles and snowballs via photodissociation. Indeed, the possibilities appear to be endless.