1. Velocity-map ion imaging studies of unconventional photochemistry
2. Spectroscopy and kinetics of reactive intermediates
Alkene ozonolysis is an important tropospheric reaction that produces a highly internally excited primary ozonide which then decays into a stable carbonyl and an unstable carbonyl oxide, R1R2COO, known as a Criegee intermediate. Subsequent reactions with trace atmospheric gases leads to formation of acids, peroxides and new particles, affecting air quality. We use broadband transient absorption spectroscopy, along with cavity ringdown spectroscopy, to study these intermediates.
Our recent work has studied the kinetics of the reactions of the simplest Criegee intermediate, CH2OO, with inorganic acids. The findings indicate that reactions with HNO3 and HCl are very fast, and that HNO3 is a significant sink for CH2OO in polluted urban environments under dry conditions.
Our current research is looking at the reactions of alcohols with CH2OO.
3. Pre-reactivity in van der Waals complexes
In addition to the transition state, the long-range region of intermolecular potential energy surfaces can have a profound influence on the dynamics of bimolecular reactions. By preparing van der Waals complexes between reactive species, it will be possible to optically prepare quasibound states that will predissociate or prereact. We use a combination of molecular beam, laser spectroscopy and ion imaging techniques to explore these transient species and the ensuing dynamics in great detail.