Rotational quenching of CO2 by collision with He atoms.

Quantum mechanical scattering calculations are presented for the rotational relaxation of CO(2) in collisions with He atoms with the close-coupling approach and the coupled-states approximation for collision energies between 10(-6) and 10 000 cm(-1). The He-CO(2) interaction potential of Ran and Xie [J. Chem. Phys. 128, 124323 (2008)] was adopted and used to compute state-to-state cross sections for the quenching of the j=2, 4, 6, and 8 rotational levels of CO(2). Numerous resonances, as a consequence of the van der Waals potential, are observed and the cross sections are found to approach the Wigner limit at low energies. Quenching rate coefficients are obtained for temperatures between 10(-5) and 3000 K and applications to astrophysics and cold collisions are briefly discussed.

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