A Simple Picture for the Rotational Enhancement of the Rate for the F + HCl → HF + Cl Reaction:  A Dynamical Study Using a New ab initio Potential Energy Surface

Abstract

Quantum scattering calculations for the reaction F + HCl --> HF + Cl are performed on a new ground-state ab initio potential energy surface. The reagent rotation is found to have a dramatic effect on the reaction probability. Furthermore, the exit channel rotational thresholds leave a strong imprint on the reaction probabilities and even on the cumulative reaction probability. A very simple vibrationally adiabatic model is shown to account for most aspects of the reaction dynamics. In this model, the fast vibrational motion is adiabatically eliminated leaving the key reaction dynamics represented by a reduced atom + rotor collision. The shape of the adiabatic potential surface immediately yields to a simple and intuitive interpretation for the rotational enhancement of the rate. The rotational enhancement is shown to be an effect of the entrance channel dynamics of the atom-rotor problem.

Accurate quantum wave packet calculations for the F + HCl → Cl + HF reaction on the ground 12A′ potential energy surface

“…All these trends agree quite well with the timeindependent results by Skodje and co-workers. 5 Wave packet integral cross sections as a function of collision energy (excitation functions) for the F + HCl (v = 0, j = 0-10) → Cl + HF reaction from the threshold up to 0.5 eV collision energy are displayed in Figure 4. To the best of our knowledge, these are the first accurate converged quantum wave packet excitation functions for E c up to 0.5 eV for the title reaction.…”

“…The title reaction has been the subject of many theoretical [1][2][3][4][5][6][7][8][9] and experimental [10][11][12] studies. Experimentalists, have focused on the determination of thermal rate constants.…”

“…4 The first theoretical reaction probabilities on this PES were calculated by Hayes et al 5 employing the QCT and hyperspherical time-independent (TI) quantum scattering methods. In their work, cumulative and initial rotational state-selected reaction probabilities, final state rovibrational distributions and summed over final states quantum reaction probabilities for different values of total angular momentum J = 0-4, at the fixed collision energy E c = 4.7 kcal/mol, were calculated.…”

State-to-state quantum dynamics of the F + HCl (vi = 0, ji = 0) → HF(vf, jf) + Cl reaction on the ground state potential energy surface

“…25 The transition state on this PES is located at a strongly bent geometry (+FHCl = 123.51) with a classical barrier height of 3.8 kcal mol À1 relative to F + HCl reactants. An interesting feature of this reaction is that the reactant rotational excitation leads to a significant enhancement in reactivity, [26][27][28][29] …”

Spectroscopy of free radicals and radical containing entrance-channel complexes in superfluid helium nanodroplets

“…Recently, strong rotational enhancement has been described for the F + HCl reaction [150,154]. The chemiluminescence from HF produced in chemical lasers, i. e. from reactions of ClF with hydrogen, has been observed [155].…”