Resonances in the entrance channel of the elementary chemical reaction of fluorine and methane

Extending the fully quantum-state-resolved description of elementary chemical reactions beyond three or four atom systems is a crucial issue in fundamental chemical research. Reactions of methane with F, Cl, H or O are key examples that have been studied prominently. In particular, reactive resonances and nonintuitive mode-selective chemistry have been reported in experimental studies for the F+CH₄→HF+CH₃ reaction. By investigating this reaction using transition-state spectroscopy, this joint theoretical and experimental study provides a clear picture of resonances in the F+CH₄ system. This picture is deduced from high-resolution slow electron velocity-map imaging (SEVI) spectra and accurate full-dimensional (12D) quantum dynamics simulations in the picosecond regime. Chemical reactivity: Experimental and theoretical data consistently demonstrate the existence of resonances in the entrance channel of the F+CH₄→HF+CH ₃ reaction shown by transition-state spectroscopy (see picture; Δ_SO=atomic spin-orbit splitting). Based on full-dimensional quantum dynamics simulations, a clear picture is drawn explaining the resonances.