Speaker: Michael Burt, University of Oxford
Program Description:
Molecular function derives from structure, and this relationship spurs innovation across chemistry. Gas-phase structures reveal the inherent chemistry of molecules at stationary points along reaction pathways, and are routinely characterized by comparing thermochemistry or electronic structure calculations with mass or infrared action spectra. Such methods are typically limited by the need for ion trapping or resonant photon absorption schemes, and often rely on interpreting uncongested spectra. This seminar will discuss Coulomb explosion imaging (CEI) as an effective alternative that can simultaneously characterize the gas-phase structures and reaction dynamics of electronic state-selected molecules. In CEI, intense ultrashort laser pulses are used as a quasi-universal ionization source to excite a target molecule to a highly charged and unstable state, which then explodes into fragments with largely Coulombic trajectories. Case studies will be presented that demonstrate how molecular structures and stereochemistry can be established by measuring and correlating the velocities of the explosion fragments, and will additionally illustrate how the fragment velocities themselves can be used to identify reaction dynamics. Collectively, these outcomes present opportunities to directly image molecules as they evolve, and to clarify their fundamental chemistry.
