Roads leading to roam. Role of triple fragmentation and of conical intersections in photochemical reactions: experiments and theory on methyl formate

摘要: The exploration of alternative roads that open to molecules with sufficient energy yield different products permits prediction and eventually control the outcomes chemical reactions. Advanced imaging techniques for monitoring laser-induced photodissociation are here combined dynamical simulations, involving ample sets classical trajectories generated on a quantum potential surface. Methyl formate, HCOOCH3, is photodissociated at energies near triple fragmentation threshold into H, CO OCH3. Images velocity rotational distributions exhibit signatures routes, such as those recently designated transition-state vs. roaming-mediated. Furthermore, demonstration route given, also confirmed by H-atom product FTIR time-resolved spectra intermediate HCO radical. In addition, relevance nonadiabatic transitions promoted conical intersection clarified simulations privileged “reactivity funnel” organic photochemistry, whereby molecular photoexcitation delivered electronic ground states.