S(¹D) + ortho-D₂ Reaction Dynamics at Low Collision Energies: Complementary Crossed Molecular Beam Experiments and Theoretical Investigations

Abstract

The excitation function of the S((1)D) + D2 reaction was determined in a crossed molecular beam apparatus for collision energies ranging from 1817 to 47 J mol(-1) in the near-cold regime. A very good overall agreement was found between experimental data and the theoretical results obtained using the ab initio potential energy surface built by Ho and coworkers and different methods: time-independent quantum dynamics (QM), semiclassical mean potential capture theory (sc-MPCT), and quasi-classical trajectories (QCT). The general trend of the experimental excitation function is well reproduced in most of the range by a simple capture calculation with an R(-6) dispersion potential. The present results are discussed in the light of previous studies on the isotopic variants S((1)D) + H2 and HD.

The Dynamics of the S(1D)+H2/D2 Reactions at Low Temperature via Statistical Simulations

“…Ratio between the ICSs for the S( 1 D)+H2 and S( 1 D)+D2 reactions at specific values of the collision energy (in eV) obtained with the SQM (second column) and MPPST (third column) approaches in comparison with those adapted from the EQM cross sections of Ref. [7] (in fourth column) and the experimental values of Ref. [2] (in the last column).…”

“…supporting a number of bound and resonance states. In fact, many authors have concluded that the overall dynamics of the reaction is ruled by this complex-forming mechanism [3,9,10], which warrants the use of statistical techniques to investigate the process [3,7,[11][12][13][14][15][16][17]. In this sense, we present in this work results of calculations performed with the statistical quantum model (SQM) [13,14,18] and the mean potential phase space theory (MPPST) [19,20].…”

“…Lee and Liu [1][2][3], the dynamics of the S( 1 D)+H2 → SH+H reaction and its corresponding isotopic variants, with substitutions of H atoms by D, have been investigated in some detail by means of kinetics and crossed molecular beam (CMB) experiments [4][5][6][7] at very low temperature (down to ≈ 6 K) and energy (≈ 0.5 meV). Those studies were accompanied by time independent exact quantum mechanical (EQM) calculations performed on the ab initio potential energy surface (PES) for the ground electronic state 1 A' reported in Ref.…”

When Classical Trajectories Get to Quantum Accuracy: The Scattering of H2 on Pd(111)

“…Gaussian binning (GB) 16,[29][30][31] and the adiabaticity correction (AC) 32 have been proposed some years ago in order to account for product vibrational quantization, and classical overweighting of adiabatic non-reactive collisions, respectively. These corrections, both supported by semiclassical arguments, 29,33 were recently shown 29,33,34 to significantly improve the capability of the QCT method to describe gas-phase and gas-surface barrierless reactions in the quantum regime, where only a few internal states are available to the reactants and/or products.…”

Statistical investigations of the S(1D)+HD reaction in the quantum regime

“…In the past years a lot of work has been devoted to investigate in detail the dynamics of the S( 1 D)+H 2 reaction and isotopic variants in which one or both hydrogen atoms are substituted by deuterium. The pioneering work by Lee and Liu [1,2,3,4] has been recently completed with further kinetics and crossed molecular beam (CMB) measurements which have provided valuable information on these reactions at very low temperature (down to T ≈ 6 K) and collision energies (E c ≈ 0.5 meV) [5,6,7,8]. These experimental investigations were accompanied with theoretical calculations of integral cross sections (ICSs) and rate constants by means of an time independent (TI) exact quantum mechanical (EQM) method employing the potential energy surface (PES) by Ho et al [9].…”