Merged-Beams Study of the Reaction of Cold HD^{+} with C Atoms Reveals a Pronounced Intramolecular Kinetic Isotope Effect.

We present a merged-beams study of reactions between HD^{+} ions, stored in the Cryogenic Storage Ring (CSR), and laser-produced ground-term C atoms. The molecular ions are stored for up to 20 s in the extreme vacuum of the CSR, where they have time to relax radiatively until they reach their vibrational ground state (within 0.5 s of storage) and rotational states with J≤3 (after 5 s).

Experimental study of the proton-transfer reaction C + H → CH + H and its isotopic variant (D).

We report absolute integral cross section (ICS) measurements using a dual-source merged-fast-beams apparatus to study the titular reactions over the relative translational energy range of Er ∼ 0.01-10 eV. We used photodetachment of C- to produce a pure beam of atomic C in the ground electronic 3P term, with statistically populated fine-structure levels.

The Intricate Dynamics of the Si(P) + OH(XΠ) Reaction.

The dynamics of the Si(P) + OH(XΠ) → SiO(XΣ,',') + H(S) reaction is investigated by means of the quasi-classical trajectory method on the electronic ground state XA' potential energy surface in the 10-1 eV collision energy range. Although the reaction involves the formation of a long-lived intermediate complex, a high probability for back-dissociation to the reactants is found because of inefficient intravibrational redistribution of energy among the complex modes. At low collision energies, the reactive events are governed by a dynamics with mixed direct/indirect features.

Time-Dependent Quantum Wave Packet Study of the Si + OH → SiO + H Reaction: Cross Sections and Rate Constants.

The dynamics of the Si(P) + OH(XΠ) → SiO(XΣ) + H(S) reaction is investigated by means of the time-dependent wave packet (TDWP) approach using an ab initio potential energy surface recently developed by Dayou et al. ( J. Chem.

A global ab initio potential energy surface for the X2A' ground state of the Si + OH → SiO + H reaction.

We report the first global potential energy surface (PES) for the X(2)A' ground electronic state of the Si((3)P) + OH(X(2)Π) → SiO(X(1)Σg(+)) + H((2)S) reaction. The PES is based on a large number of ab initio energies obtained from multireference configuration interaction calculations plus Davidson correction (MRCI+Q) using basis sets of quadruple zeta quality. Corrections were applied to the ab initio energies in the reactant channel allowing a proper description of long-range interactions between Si((3)P) and OH(X(2)Π).

Observation of partial wave structures in the integral cross section of the S((1)D2) + H2(j = 0) reaction.

The integral cross section of the S((1)D(2)) + H(2)(j = 0) → SH + H reaction has been measured for the first time at collision energies from 0.820 down to 0.078 kJ mol(-1) in a high-resolution crossed beam experiment.

Kinetics and dynamics of the S(1D2) + H2 → SH + H reaction at very low temperatures and collision energies.

We report combined studies on the prototypical S(1D2) + H2 insertion reaction. Kinetics and crossed-beam experiments are performed in experimental conditions approaching the cold energy regime, yielding absolute rate coefficients down to 5.8 K and relative integral cross sections to collision energies as low as 0.

Si(3P) + OH(X2Pi) interaction: long-range multipolar potentials of the eighteen spin-orbit states.

Eighteen spin-orbit states are generated from the open-shell open-shell Si((3)P) + OH(X(2)Pi) interacting system. We present here the behavior of the associated long-range intermolecular potentials, following a multipolar expansion of the Coulombic interaction treated up to second order of the perturbation theory, giving rise to a series of terms varying in R(-n). In the present work, we have considered the electrostatic dipole-quadrupole (n = 4) and quadrupole-quadrupole (n = 5) interactions, as well as the dipole-induced dipole-induced dispersion (n = 6) and dipole-dipole-induced induction (n = 6) contributions.

Long-range multipolar potentials of the 18 spin-orbit states arising from the C(3P) + OH(X 2Pi) interaction.

We present multipolar potentials at large intermolecular distances for the 18 doubly degenerate spin-orbit states arising from the interaction between the two open-shell systems, C((3)P) and OH(X (2)Pi). With OH fixed at its ground vibrational state-averaged distance r(0), the long-range potentials are two-dimensional potential energy surfaces (PESs) that depend on the intermolecular distance R and the angle gamma = CGH, where G represents the mass center of OH. The 18x18 diabatic potential matrix elements are built up from the perturbation theory up to second order and from a two-center expansion of the Coulombic interaction potential, resulting in a multipolar expansion of the potential expressed as a series of terms varying in R(-n).

A comparative study of the Si+O(2)-->SiO+O reaction dynamics from quasiclassical trajectory and statistical based methods.

The dynamics of the singlet channel of the Si+O(2)-->SiO+O reaction is investigated by means of quasiclassical trajectory (QCT) calculations and two statistical based methods, the statistical quantum method (SQM) and a semiclassical version of phase space theory (PST). The dynamics calculations have been performed on the ground (1)A(') potential energy surface of Dayou and Spielfiedel [J. Chem.

Spin-orbit coupling in O2(v)+O2 collisions. II. Quantum scattering calculations on dimer states involving the X 3 Sigma g -, a 1 Delta g, and b 1 Sigma g + states of O2.

The dynamics of collisional deactivation of O(2)(X (3)Sigma(g) (-),v=20-32) by O(2)(X (3)Sigma(g) (-),v(')=0) is investigated in detail by means of quantum-mechanical calculations. The theoretical approach involves ab initio potential energy surfaces correlating to the X (3)Sigma(g) (-), a (1)Delta(g), and b (1)Sigma(g) (+) states of O(2) and their corresponding spin-orbit couplings [F. Dayou, M.

Intermolecular potential of the O2-O2 dimer. An ab initio study and comparison with experiment.

Accurate intermolecular potentials for the lowest three multiplet states of O2-O2 dimer have been produced on the basis of ab initio calculations. The quintet potential was taken from previous highly correlated CCSD(T) calculations. In this work, we perform MRCI calculations, with large basis sets including bond functions, of the singlet and triplet states, which are of multireference character.

Spin-orbit coupling in O2(upsilon)+O2 collisions: I. Electronic structure calculations on dimer states involving the X 3Sigmag-, a 1Deltag, and b 1Sigmag+ states of O2.

The importance of vibrational-to-electronic (V-E) energy transfer mediated by spin-orbit coupling in the collisional removal of O2(X 3Sigmag-,upsilon>or=26) by O2 has been reported in a recent communication [F. Dayou, J. Campos-Martinez, M.

Spin-orbit coupling in O2(v)+O2 collisions: a new energy transfer mechanism.

A reduced dimensionality model is used to study the relaxation of highly vibrationally excited O(2)(X (3)Sigma(g) (-),v>/=20) in collisions with O(2)(X (3)Sigma(g) (-),v=0). Spin-orbit coupled potential energy surfaces are employed to incorporate the vibrational-to-electronic energy transfer mechanism involving the O(2)(a (1)Delta(g)) and O(2)(b (1)Sigma(g) (+)) excited states. The transition probabilities obtained show a sharp increase for v>/=26 providing the first direct evidence of the important role played by the electronic energy transfer processes in the depletion of O(2)(X (3)Sigma(g) (-),v>/=26).