Appearance of Low Energy Resonances in CO-Para-H2 Inelastic Collisions

We report on crossed-beam experiments and quantum-mechanical calculations performed on the CO(j = 0) + H-2(j = 0) -> CO(j = 1) + H-2(j = 0) system. The experimental cross sections determined in the threshold region of the CO(j = 0 -> j = 1) transition at 3.85 cm(-1) show resonance structures in good qualitative agreement with the theoretical ones. These results suggest that the potential energy surface which describes the CO-H-2 van der Waals interaction should be reinvestigated for good quantitative agreement.