Patrick H. Vaccaro of Yale University is supported by the Chemical Structure, Dynamics, and Mechanisms Program of the Chemistry division to investigate fundamental aspects of molecular behavior responsible for physical properties and chemical propensities. Novel forms of linear and nonlinear laser spectroscopy are enlisted to interrogate gas-phase species exhibiting key phenomena that permeate molecular science, including hydrogen bonding, proton transfer, and optical activity. Building on the unique capabilities of nonlinear optical spectroscopy, Prof. Vaccaro and his research group explore vibrationally mediated proton transfer in tropolone and related species, with extensions of such studies to weakly bind adducts allowing cooperative aspects of multiple proton-transfer reactions to be examined. Ultrasensitive chiroptical techniques based upon cavity ring-down polarimitry are used to interrogate the dispersive (circular birefringence) and absorptive (circular dichroism) components of natural optical activity in rarefied media, thereby elucidating the role of solvation, conformation, and vibration on intrinsic chiroptical response. The latter work has provided a number of important and non-intuitive insights, while also serving to assess computational predictions for the optical properties of chiral molecules.
Hydrogen bonding and proton transfer are ubiquitous in nature, responsible for mediating the structure and dynamics of diverse systems ranging from liquid water to in vivo biomolecules. Besides impacting broad realms of chemical research, participating students are trained in a multidisciplinary environment that emphasizes contemporary methods of molecular spectroscopy and related aspects of optical/laser technology, thereby preparing them to enter the modern technical workforce. Since his research group historically has been primarily female in character, Prof. Vaccaro also is contributing to increasing the number of career scientist drawn from this particular underrepresented group.
