Resonance-Mediated Chemical Reaction:F+HD→HF+D

Abstract

Conclusive evidence is presented for the existence of a reactive resonance in the F+HD reaction. In a molecular beam experiment, the resonance appears in the integral cross section as a distinct steplike feature, while in the differential cross section it is manifested as sharply varying forward-backward peaks in the product distribution. A detailed analysis of the quantum dynamics establishes that a reactive resonance localized in the transition-state region is responsible for these remarkable observations. At collision energies below 1 kcal/mol, the reaction proceeds almost exclusively through resonant tunneling with very little contribution from the more conventional direct mechanism.

Dynamics of theS(D21)+HD(j=0Lara1, Chefdeville2, Hickson3 et al. 2012Phys. Rev. Lett.423290View full textAdd to dashboardCite

“…Peaks arising from partial-wave resonances have to date only been observed in the state-to-state DCSs corresponding to a particular HF quantum state for a restricted set of scattering angles in the F þ HD ! FH þ D reaction [6] while appearing as a steplike feature in the ICSs [5]. It is known that strengths, shapes, and energies of resonance features as calculated by theoretical methods remain very sensitive to the PESs and the QM methods that are utilized.…”

“…This has followed the exquisite agreement between theory and experiment found for the benchmark three-atom F þ HD ! HF þ D [5,6] and F þ H 2 ! HF þ H [7,8] reactions for which resonance features have been fully rationalized.…”

An extension of the grid empowered molecular simulator to quantum reactive scattering

“…Finally, even if GEMS showed to be able to cope with the calculation on the grid of thermal rate coefficients via the evaluation of initial state-selected reaction probabilities obtained from different quantum scattering techniques (both TD [40][41][42][43] and TI), [44][45][46] we also investigated the case in which initial statespecific reaction probabilities are evaluated starting from wave packet simulations started in the transition state region and using flux correlation functions. This strategy is labeled within this work as the transition state wave packet scheme.…”

Chemistry at surfaces: from ab initio structures to quantum dynamics

“…The H + H 2 isotopic family of reactions is the best known example for quantized dynamical bottlenecks which lead to an observable time-delayed mechanism [147,148], and interference features [149,150]. The F + HD→HF + D reaction is the first reaction for which conclusive evidence has been found for a Feshbach resonance in a full collisional dynamics [151,152] and only recently experimental evidence has been found for some polyatomic reactions [153][154][155]. We found clear quantum signatures in global observables like total EleyRideal cross sections, which indicate that some cautions are needed when applying classical methods to light atom dynamics, even when the reaction system, the reaction conditions or the observable to be computed suggest them to be adequate.…”