State-to-state rotational excitation of CO by H2 near 1000 cm-1 collision energy

Relative state-to-state rotationally inelastic cross sections for excitation of carbon monoxide by hydrogen were measured in a crossed molecular beam experiment at collision energies 795, 860, and 991 cm(-1). The results are compared to predictions of a recent ab initio potential energy surface [J. Chem. Phys. 108, 3554 (1998)]. The agreement is very good. A comparison with older data on thermally averaged total depopulation cross sections [Chem. Phys. 53, 165 (1980)] indicates that the absolute magnitudes of the cross sections predicted by the surface are too high. The CO excitation is dominated by collisions that are elastic in H-2 rotation, and the collision dynamics are very similar for different rotational levels of hydrogen. (C) 2000 American Institute of Physics. [S0021-9606(00)01702-5].