The temperature dependence of hydrogen abstraction reactions: F+HCl, F+HBr, F+DBr, and F+HI

Abstract

Time-dependent quantum wave packet studies of the F+HCl and F+DCl reactionsExamination of the Br+HI, Cl+HI, and F+HI hydrogen abstraction reactions by photoelectron spectroscopy of BrHI−, ClHI−, and FHI− Molecular beam scattering experiments on the abstraction and exchange reactions of deuterium atoms with the hydrogen halides HCl, HBr, and HI A laser photolysis/infrared fluorescence technique has been used to study the temperature dependence of the F + HCI, F + HBr, F + DBr, and F + HI absolute rate constants in the range from 195 to 373 oK.Multiphoton dissociation of SF 6 with a TEA CO 2 laser was used to provide a. transient concen~ratlon of fluorine atoms. Their subsequent reaction with hydrogen donors was momtored by observmg the appearance rate of HF(v ;:>: 1) through its infrared fluoresce~ce. The observed. rate co~stants show a marked nonlinear Arrhenius behavior which is consistent wIth a model m whIch reac~lOn takes pl.a~ both via direct attack by the fluorine atom at the hydrogen end of HX and via formation of a colhslon complex FXH which rearranges to FHX and then dissociates to HF and X products.

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

“…15 Later, Würzberg and Houston measured the absolute rate constant over the range 195 to 373 K, and observed a remarkable nonlinear Arrhenius behavior. 16 A similar study was reported by…”

“…The work of Bulut et al 29 shows that the rate constants predicted by calculations with this PES are an order of magnitude smaller than experimental estimates. 16,17 In addition, they concluded that quantum tunneling will not make a significant contribution to the thermal reaction rates. Sayos et al 22 scaled their PES to mimic the barrier on the LEPS PES used by Ding et al 15 (E a = 1.1 kcal mol À1 ).…”

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

“…Experimentalists, have focused on the determination of thermal rate constants. Wurzberg et al 10,11 and Moore et al 12 measured absolute rate constants in the temperature range 195-373 K and 195-294 K, respectively, using laser photolysis techniques. The measured thermal rate constants were found to follow a non-Arrhenius behavior over the studied temperature range.…”

“…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.…”

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

“…The X-HF [145][146][147][148][149][150] and X-HCN [151][152][153] PES have also been studied in collision experiments. Recently, strong rotational enhancement has been described for the F + HCl reaction [150,154].…”