State-to-state dynamics of H+HX collisions. II. The H+HX→HX°+H (X=Cl,Br,I) reactive exchange and inelastic collisions at 1.6 eV collision energy

Abstract

Articles you may be interested inPhotogeneration of ions via delocalized charge transfer states. II. HX2 − (X=Cl,Br,I) in rare gas matrices J. Chem. Phys. 98, 3914 (1993); 10.1063/1.464018 Statetostate dynamics of H+HX collisions. I. The H+HX→H2+X (X=Cl,Br,I) abstraction reactions at 1.6 eV collision energy J. Chem. Phys. 90, 4795 (1989); 10.1063/1.456574Experimental study of the dynamics of D+H2 reactive and inelastic collisions below 1.0 eV relative energyWe report measurement of product state distributions for the rotationally and/or vibrationally excited HX formed in collisions oftranslationally hot H atoms with HX (X = CI, Br, and I) at 1.6 eV collision energy. The product state distributions are probed after only one collision of the fast H atom, using coherent anti-Stokes Raman scattering spectroscopy. Whether proceeding by inelastic collisions or reactive exchange, the transfer of translational energy to vibrational and rotational energy is quite inefficient in H + HX collisions at 1.6 eV. For all three hydrogen halides only 2-3% ofthe initial translational energy appears as HX vibration.For H + HC} only 6% ofthe initial energy is converted to HCI rotational energy, while for H + HBr and H + HI, this percentage is twice as large, 11-12%, but still small. The indistinguishability of the two H atoms involved makes it impossible to distinguish reactive exchange from inelastic energy transfer in these H + HX collisions. However, the difference in rotational energy partitioning for H + HBr and H + HI as compared with H + HCI, suggests that reactive exchange is dominant in the former and inelastic energy transfer dominates in the latter. The total cross sections for the combined energy transfer/reactive exchange do not change much with the identity of X, being 13 ± 3, 11 ± 2, and 11 ± 2 ft.?, for H + HCI, H + HBr, and H + HI, respectively.

Theoretical studies of product polarization and state distributions of the H+HCl reaction

“…The abstraction cross-sections of the H + HCl and D + HCl reactions obtained from the experimental measurements are well justified by QCT calculations on the G3 PES [43]. As another important elementary step in the mechanism of the Cl 2 þ H 2 chain reaction, the dynamical behavior of the H + HCl reaction is also a very interesting subject, but much less information is available concerning this reaction [44][45][46][47]. It is our intention in this work to get more dynamics information, and more about the PES for this system QCT calculations have been performed for the reaction of H + HCl on both BW2 and G3 PESs.…”

“…1 and 2, respectively. Valentini and co-workers [44,45] have measured the absolute reaction crosssections of the H + HCl reaction at the same collision energy and determined values of ð2 AE 1Þ and ð13 AE 3Þ A A for the abstraction channel and Fig. 1(a)) or m 0 ¼ 1 (shown in Fig.…”

“…In order to compare with the experimental measurements of the product state distributions for the H + HCl reaction [44,45], the relative translational energy is chosen to be 1.6 eV in this paper. Calculations made by Aoiz et al [43] have shown that no appreciable dependence of the cross section on the HCl reagent rotational levels was observed for the above reaction, so the trajectory is initiated with the hydrogen chloride in the v ¼ 0 and j ¼ 0 level.…”

Close-Coupling Time-Dependent Quantum Dynamics Study of the H + HCl Reaction

“…1,2 A large number of kinetics studies were carried out for the H + HCl elementary reaction in the temperature range 195 KeTe1200 K, 3 including experiments in which the influence of selective vibrational excitation of HCl on the reaction rate was investigated. [4][5][6][7][8] Recent studies [9][10][11][12][13][14][15][16] of the reaction H + HCl at a collision energy of 1.6 eV have measured the integral cross section for the abstraction channel to be (2(1) Å 2 , 9,10 where as the exchange plus energy-transfer channels gave a combined cross section of (13(3) Å 2 . 9,10 It has been shown by Wight et al 11 that the dominant process is energy transfer.…”

“…[4][5][6][7][8] Recent studies [9][10][11][12][13][14][15][16] of the reaction H + HCl at a collision energy of 1.6 eV have measured the integral cross section for the abstraction channel to be (2(1) Å 2 , 9,10 where as the exchange plus energy-transfer channels gave a combined cross section of (13(3) Å 2 . 9,10 It has been shown by Wight et al 11 that the dominant process is energy transfer. 2 In contrast to numerous experiments, only a few theoretical studies have been reported for this H + HCl reaction.…”