Unraveling unconventional photochemistry using time- and state-resolved imaging

University Of California-Irvine, Irvine CA

Investigators

Abstract

In this project funded by the Chemical Structure and Dynamics Program A of the Chemistry Division, Dr. Craig Murray of University of California, Irvine and his graduate students are using short and ultrashort laser pulses to explore interactions of small molecules with light. After absorbing light of sufficiently high energy, these small molecules dissociate via different pathways and with different time scales. Detailed information on these processes is obtained by time-resolved imaging of the products. An outreach program involves active participation in the research lab of local high school teachers, providing them with insight into some current research activity. The program additionally provides a day at university experience for their students, exposing them to opportunities available to them in higher education. The program draws connections between fundamental chemical processes studied in the laboratory and larger scale applications. This project uses velocity-map (slice) ion imaging coupled to tunable nanosecond and picosecond laser systems to measure correlated photofragment product state distributions. With this technique, unconventional photochemical processes in small gas-phase molecules are explored, such as roaming-mediated intersystem crossing, multiple roaming pathways and extrusion of atomic or radical species. Time-resolved measurements using transform-limited picosecond pulses explore how the correlated product state distributions evolve in time, identifying characteristic time-scales for roaming, intersystem crossing, and conventional dissociation mechanisms.