SACM/CT Study of the dissociation/recombination dynamics of hydrogen peroxide on an ab initio potential energy surface Part II. Specific rate constants k(E,J), thermal rate constants k∞(T), and lifetime distributions

Abstract

Statistical adiabatic channel model/classical trajectory (SACM/CT) calculations of the dissociation/recombination dynamics of hydrogen peroxide, H₂O₂ ⇔ 2HO, have been performed on an ab initio potential energy surface by Kuhn, Rizzo, Luckhaus, Quack, and Suhm (J. Chem. Phys. 1999, 111, 2565). Specific rate constants k(E,J), thermal rate constants k_∞(T), and lifetime distributions are determined. After averaging over J, the derived k(E,J) are in quantitative agreement with non-exponential time-profiles of HO formation recorded after overtone excitation of H₂O₂ near the dissociation threshold by Scherer and Zewail (J. Chem. Phys. 1987, 87, 97). The thermal high pressure rate constants for HO recombination agree with experimental data as well and can be represented by k_rec,∞/10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ ≈ [0.376 (298 K/T)^0.47 + 0.013 (T/298 K)^0.74] over the range 60–1500 K. Non-statistical lifetime distributions are suggested not to have been of major relevance for the available experiment.