Zeeman relaxation of MnH (X7{\Sigma}+) in collisions with 3He: mechanism and comparison with experiment

We present a theoretical study of the Zeeman relaxation of the magnetically trappable lowest field seeking state of MnH(^7 \Sigma) in collisions with 3He. We analyze the collisional Zeeman transition mechanism as a function of the final diatomic state and its variation as a function of an applied magnetic field. We show that as a result of this mechanism the levels with \Delta Mj>2 give negligible contributions to the Zeemam relaxation cross section. We also compare our results to the experimental cross sections obtained from the buffer gas cooling and magnetic trapping of this molecule and investigate the dependence of the Zeeman relaxation cross section on the accuracy of the three body interaction at ultralow energies

Quasiclassical determination of integral cross sections and rate constants for the N + OH --> NO + H reaction

International audienceQuasi-classical trajectory (QCT) calculations have been carried out for the reaction on an ab initio global potential energy surface for the ground electronic state, . Cross-sections, computed for collision energies between 0.001 and 1 eV, show no energy threshold and decrease with the increasing collision energy. Rate constants have been calculated in the 5–500 K temperature range. The thermal rate constant is in good agreement with previous theoretical results over a wide range of temperatures, and with the experimental data for temperatures above 300 K. Cross-sections and rate constants are found to be dependent on the initial rotation

Prediction of the existence of the N2H− molecular anion

International audienceWe predict the existence of the N2H− anion from first principle calculations. We present the threedimensional potential energy surface and the bound states of the N2H−/D− van derWaals anion. The electronic calculations were performed using state-of-the-art ab initio methods and the nuclear motions were solved using a quantum close-coupling scattering theory. A T-shaped equilibrium structure was found, with a well depth of 349.1 cm−1, where 18 bound states have been located for N2H− and 25 for N2D− for total angular momentum J = 0. We also present the absorption spectra of the N2H− complex. This anion could be formed after low energy collisions between N2 and H− through radiative association. The importance of this prediction in astrophysics and the possible use of N2H− as a tracer of N2 and H− in the interstellar medium is discussed

Quasiclassical trajectory scattering calculations for the O + OH → H + O2 reaction: cross sections and rate constants

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