Classical state-to-state Ar-CO2 rotational cross-sections are calculated us
ing two potentials. Comparison with experimental data shows that there are
discrepancies. The two-dimensional atom-ellipsoid model is used to analyse
the cause of these discrepancies, and it is found that the cross-sections a
re sensitive to multiple collision effects. The results, considering only t
he contribution of the repulsive part of the two potentials, showed satisfa
ctory agreement with the experimental measurements but, on taking into acco
unt the whole potentials, some deviations from the experimental state-to-st
ate rotational cross-sections were observed. These deviations were attribut
ed to the strong contribution from the long-range part of each potential.