The He-N2 interaction revisited: A comparison of measured and computed differential cross sections

A recently proposed anisotropic potential for the interaction between the He (1S) and the N2 molecule (1-SIGMA-g) treated as a rigid rotor (RR) is compared with the experimental differential cross sections that exist at two different collision energies and with one of the previously suggested potential energy surfaces (PES) which had been found earlier to provide the best fit to all known experimental data. Different dynamical approximations are employed and the comparison is made both with total cross sections and with partial, state-to-state rotationally inelastic cross sections. It is shown that the new potential (called BTT) is able to reproduce the total angular distribution measurements but fails to do so with the partial inelastic cross sections, thus indicating an overall anisotropy of its well region which is too weak to be realistic. The importance of testing PES anisotropies against experimental, energy-resolved state-to-state distributions is once again underlined by the present calculations, which once more confirm the quantitative validity of IOSA decoupling scheme for weak van der Waals systems at the energies of the existing crossed beam experiments.