Rotational energy transfer in the NOAr system and the validity of the different forms of the potential

Theoretical investigations of the rotational transitions in the NO(A2Σ+) state due to collisions with Ar have been carried out by testing different forms of potential functions. It is found that the cross sections predicted by the pairwise sum of the potential, V = V(NAr) + V(OAr) differs from the experimental cross sections by a factor of 3 or more if the pairwise interaction term V(NAr) as well as V(OAr) is taken as a spherically symmetric Lennard-Jones potential. The agreement, however, improves considerably if the term V(NAr) as well as V(OAr) is made dependent on the orientation of the NO bond. A general form of the potential function which is expressed as an expansion in terms of Legendre polynomials has also been investigated and compared with the former potential.