Dynamics of Insertion Reactions of H₂Molecules with Excited Atoms

Abstract

Recent progress in the study of insertion reactions of hydrogen molecules with excited atoms is reviewed in this article. In particular, the dynamics of the reaction of O(1D), N(2D), C(1D), and S(1D) with H2 and its isotopomers, which have received a great deal of attention over the past decade, are examined in detail. All of these systems have in common the existence of several potential energy surfaces (PES) correlating with the reagents' states, and consequently, they can give rise to reaction following different adiabatic and nonadiabatic pathways. The main contribution, however, arises from their ground singlet PESs which feature the existence of deep wells with small or null barriers for insertion. Accordingly, these reactions proceed mainly via formation of relatively long-lived collision complexes and display an overall nearly statistical behavior. In spite of their similarities, the various reactions have peculiar characteristics caused by important differences of their respective PESs. The contribution of excited PES to the global reactivity, which has also become an important issue and a challenge both for theory and experiment, is also examined. The different theoretical approaches are discussed in the text, along with the experimental results obtained by a variety of techniques. The recent exact quantum treatments of these reactive systems together with the development of a rigorous statistical model have contributed to a very accurate description which in many cases matches very well the detailed measurements. The quasi-classical trajectory (QCT) method has also provided a fairly accurate description of the reaction dynamics for these systems. In particular, the analysis in terms of collision times has yielded interesting clues about the reaction mechanisms.

Vibrationally inelastic collisions of H+D2: A comparison of quantum mechanical, quasiclassical, and experimental results

“…The QM and QCT opacity functions P͑J͒ are similar to those previously presented at a higher collision energy ͑E coll = 1.85 eV͒. 1 As in that case, the agreement between QM and QCT data is only qualitative with roughly similar shapes. The value of J max leading to vЈ =3 is Ϸ30 ͑b max = 1.19 Å͒ in both the QM and QCT calculations.…”

Extraction of state-to-state reactive scattering attributes from wave packet in reactant Jacobi coordinates

“…53 It is also a benchmark reaction for the development of new theoretical methods. Aoiz et al 54 recently gave a comprehensive progress review on the dynamical study of this reaction. An excellent agreement between theory and experiment has been achieved for this reaction on the BKMP2 potential energy surface ͑PES͒ 55-58 as well as on the latest CCI PES.…”

State-to-state reactive differential cross sections for the H+H2→H2+H reaction on five different potential energy surfaces employing a new quantum wavepacket computer code: DIFFREALWAVE

“…Aoiz et al recently reviewed the progress in the study of the dynamics of this reaction. 26 With advances in experimental 27,28 and theoretical 29 methods very good agreement between theory and experiment has been achieved and only a few issues remain unresolved. 26 Several global analytic potential energy surfaces ͑PESs͒ are available, the LSTH surface, 30,31 the DMBE surface, 32 and the BKMP ͑Ref.…”

“…Accurate quantum calculations employing the BKMP2 surface produced results in very good agreement with the experiment. 26 Four years ago Mielke et al 36 calculated a set of three potential energy surfaces for the H + H 2 exchange reaction using a hierarchical family of basis sets. These were then used to estimate the complete basis set limit of the calculations, thus generating a fourth surface, labeled as the CCI surface.…”