Abstract

The hydroxyl radical plays a major role in atmospheric and combustion environments where it is often detected using laser-induced fluorescence. I will discuss the intermolecular interactions between OH radicals and partner molecules found in these environments from two different perspectives. In the first part, I will describe the current data on the hydrotrioxy radical (HOOO), which has been postulated to be an intermediate in several atmospheric reactions and potentially a temporary sink for OH through association with molecular oxygen. Infrared action spectroscopy has been used to characterize the vibrational modes of both conformers of HOOO , give insight into the nature of the bonding and provide a rigorous upper limit to the dissociation energy. In the second part, I will discuss the dynamical outcomes of collisional quenching of electronically excited OH radicals by molecular partners, through measurements of nascent ground state population distributions and the branching between reactive and non-reactive pathways. The observations will be rationalized as dynamical signatures of the non-adiabatic passage through seams of conical intersection that couple the ground and electronically excited PESs.