Spectroscopic Probes of Molecular Structure and Dynamics

Yale University, New Haven CT

Investigators

Abstract

With this award, the Chemical Structure, Dynamics and Mechanisms (CSDM-A) Program of the Division of Chemistry is funding Professor Patrick Vaccaro of Yale University to investigate subtle effects in the way molecules interact with light and with other molecules. One of the two thrusts in the work supported by this award looks at the way light interacts with molecules with "handedness" -- for example, many molecules, especially biologically important molecules have non-superimposable mirror images, which is one kind of "handedness." The spectroscopic methods being developed in the Vaccaro laboratory aim to discriminate between different handed isomers of these molecules, as well as providing accurate benchmarks for theorists interested in modelling this phenomena. In the other thrust, the work will look at weakly interacting molecules in order to improve our understanding of the very subtle forces that molecules feel for each other. Professor Vaccaro's research students will be trained in optical and vacuum science as well as instrument design and construction. In an outreach project supported by this award, Professor Vaccaro and his students will work with students and teachers in the New Haven Public Schools. The Vaccaro research group is diverse, and has historically had a large number of female scientists. Professor Patrick Vaccaro and his research group will study an interesting set of spectroscopic systems. In one set of experiments, Vaccaro and his group will extend their past work on the chiroptical spectroscopy of isolated molecules in the gas phase. In the next phase of this work, the Vaccaro group will use cavity ringdown polarimetry to probe the electronic circular dichroism and electronic circular dichroism of some fairly complex chiral molecules in the gas phase, including molecules like (R) - norbornenone and the very weakly optically active species cyclopropane-1,2-d2. This work benefits from the collaboration with a number of prominent theoretical groups. New chiroptical investigations will look at chiral solutes dissolved in a rare-gas matrix. These later studies hope to investigate the changes in chiroptical response for molecules in weakly perturbing solvents. In a separate thrust, the Vaccaro group will investigate the weak interactions between aromatic molecules by studying benzene-tropolone dimers with a variety of spectroscopic methods, including two-color resonant four-wave mixing spectroscopy.