Classical and quantum-mechanical plane switching in CO_2

    Michaël Sanrey and Marc Joyeux 
    Laboratoire de Spectrométrie Physique (CNRS UMR 5588), Université Joseph Fourier\u2014Grenoble 1, BP 87, 38402 St. Martin d'Hères, France 

    Dmitrii A. Sadovskii 
    Université du Littoral, UMR 8101 du CNRS, 59140 Dunkerque, France 

 J. Chem. Phys. 124, 074318 (2006) (12 pages)

(Received 3 October 2005; accepted 29 December 2005; published online 21 February 2006)

Classical plane switching takes place in systems with a pronounced 1:2
resonance, where the degree of freedom with the lowest frequency is doubly
degenerate. Under appropriate conditions, one observes a periodic and abrupt
precession of the plane in which the doubly degenerate motion takes place. In
this article, we show that quantum plane switching exists in CO_2. Based on our
analytical solutions of classical Hamilton's equations of motion, we describe
the dependence on vibrational angular momentum and energy of the frequency of
switches and the plane switching angle. Using these results, we find optimal
initial wave-packet conditions for CO2 and show, through quantum-mechanical
propagation, that such a wave packet indeed displays plane switching at
energies around 10 000 cm-1 above the ground state on time scales of about
100 fs. ©2006 American Institute of Physics

doi:10.1063/1.2167747
PACS: 31.15.-p, 33.15.Mt