title: Quantum dynamical resonances in low-energy CO(j = 0) + He inelastic collisions.
abstract: In molecular collisions, long-lived complexes may be formed that correspond to quasi-bound states in the van der Waals potential and give rise to peaks in the collision energy-dependent cross-sections. They are known as 'resonances' and their experimental detection remains difficult because their signatures are extremely challenging to resolve. Here, we show a complete characterization of quantum-dynamical resonances occurring in CO-He inelastic collisions with rotational CO(j = 0->1) excitation. Crossed-beam scattering experiments were performed at collision energies as low as 4 cm(-1), equivalent to a temperature of 4 K. Resonance structures in the measured cross-sections were identified by comparison with quantum-mechanical calculations. The excellent agreement found confirms that the potential energy surfaces describing the CO-He van der Waals interaction are perfectly suitable for calculating state-to-state (de)excitation rate coefficients at the very low temperatures needed in chemical modelling of the interstellar medium. We also computed these rate coefficients.
authors: 1] Université de Bordeaux, Institut des Sciences Moléculaires, Talence Cedex 33405, France [2] CNRS, UMR 5255, Talence Cedex 33405, France.
authors: Astrid
authors: A
authors: Bergeat
authors: Radboud University Nijmegen, Institute for Molecules and Materials, Heijendaalseweg 135, Nijmegen 6525 AJ, The Netherlands.
authors: Jolijn
authors: J
authors: Onvlee
authors: 1] Université de Bordeaux, Institut des Sciences Moléculaires, Talence Cedex 33405, France [2] CNRS, UMR 5255, Talence Cedex 33405, France.
authors: Christian
authors: C
authors: Naulin
authors: Radboud University Nijmegen, Institute for Molecules and Materials, Heijendaalseweg 135, Nijmegen 6525 AJ, The Netherlands.
authors: Ad
authors: A
authors: van der Avoird
authors: 1] Université de Bordeaux, Institut des Sciences Moléculaires, Talence Cedex 33405, France [2] CNRS, UMR 5255, Talence Cedex 33405, France.
authors: Michel
authors: M
authors: Costes