Rotational and vibrational excitation of CO molecules by collisions with 4He atoms

Full close-coupled calculations are carried out of the cross sections for energy transfer between rotational levels of carbon monoxide in collision with He-4 atoms with energies between 5 and 600 cm(-1). At low energies, the cross sections are dominated by contributions from shape resonances. The calculated cross sections are in satisfactory agreement with the experimental data measured at an energy of 570 cm(-1). Calculations using the infinite order sudden approximation are carried out of cross sections for energy transfer between vibrational levels of CO. Vibrational energy transfer is dominated by transitions in which the vibrational quantum number changes by unity.