Quantum-State Control on Multidimensional Potential Energy Surfaces: Driving Chemical Outcomes with Spectroscopic Accuracy

Speaker Name/Affiliation
Nathan Kidwell /William & Mary
Location (Room)
JILA Auditorium
Event Details & Abstracts

Abstract: In bimolecular collisions of atmospherically-relevant molecules such as open-shell radicals and alkanes, relative molecular configurations can significantly change reactive and non-reactive outcomes. To probe this isomer-dependence, experiments are needed that can quantify both the initial molecular configuration and internal energy of the collision partners with spectroscopic accuracy. Recent work by our group demonstrated that upon infrared (IR) excitation, the dynamics of the nitric oxide-methane collision complex (NO-CH4) are dependent on the initial monomer configurations, as small changes in configuration substantially affect the energies, electronic couplings, and predissociation pathways due to the Jahn-Teller effect. In this talk, we compare the spectroscopic signatures and dynamical outcomes from IR activation of NO-CH4 and NO-C2H6 (ethane). IR action spectroscopy with 1+1 resonance-enhanced multiphoton ionization of NO products was employed to characterize the fundamental CH stretch transitions of NO-CH4 and NO-C2H6, as well as to initiate the non-reactive decay mechanisms of the collision complexes. Furthermore, velocity map imaging (VMI) was utilized to explore the dynamics prior to and following IR excitation, imprinted on the NO photoproducts. Substantial differences in the ion image anisotropies and velocity distributions indicate separate IR-initiated dissociation mechanisms for NO-CH4 and NO-C2H6 along pseudo Jahn-Teller surfaces. An isomer-dependent framework is used to unravel the coupled vibrational and electronic dynamics in these complex bimolecular reactions.