Absolute rate coefficients for F+H2 and F+D2 at T=295–765 K.

Abstract

The rate coefficients of the F+H2 and F+D2 reactions must be accurately known over a wide temperature range if the HF and DF chemical lasers are to be properly modeled. Although the pulsed and cw chemical lasers operate at elevated temperatures (500 to 2000 K), no absolute rate data exist for T≳400 K. Extension of the infrared multiphoton dissociation–infrared fluorescence technique permitted the following Arrhenius equations to be determined between 295 and 765 K: kF+H2=(1.3±0.25)×1014 exp[−(1182±100)/RT]; kF+D2=(6.4±2.2)×1013 exp [−(1200±142)/RT]; kF+H2/kF+D2=(2.1±0.8) exp[(18±250)/RT].

“Direct” Calculation of Thermal Rate Constants for the F + H2 → HF + F Reaction

“…The PA/HCA, which uses one of the instantaneous principal axes as the body-fixed axis for the purpose of making the helicity-conserving approximation, is thus preferred. Figure 3 is an Arrhenius plot of the present results compared with those from previous experiments [43][44][45] and theoretical calculations. 38 The numerical values of the rates are given in Table 2.…”

Quantum state-resolved reactive scattering of F+H2 in supersonic jets: Nascent HF(v,J) rovibrational distributions via IR laser direct absorption methods

“…[26][27][28] The experimental literature on FϩH 2 reactions is impressively extensive. From a thermally averaged perspective, there have been numerous temperature-dependent kinetic studies of FϩH 2 reactions, which have provided rate constants, activation energies, and Arrhenius pre-exponential factors [29][30][31] for the atom abstraction event. Such results provide useful experimental constraints with which to test both potential surfaces and dynamics calculations, but the strength of these comparisons is substantially weakened by extensive thermal averaging over the initial and final quantum state distributions of reagents and products.…”

The kinetics of the reaction F + H2 ? HF + H. A critical review of literature data

“…The results of Heidner et al [4] are also problematic with regard to the calculated kinetic isotope effect. The isotope effect calculated from their results is practically independent of temperature, which means that the activation energy for both reactions, F ϩ H 2 and F ϩ D 2 , is approximately the same.…”

“…[18]). The values of the individual rate constants k FϩCH 4 and k FϩH 2 determined by Clyne and Hodgson [17,11] can be used to calculate the ratio of rate constants k FϩCH 4 /k FϩH 2 ϭ 2.60 Ϯ 0.20. This value is in very good agreement with values determined more directly by other research groups including the value 2.55 Ϯ 0.13 determined in our laboratory [18] (a summary is given in Table II of ref.…”