Ab   initio potential energy surfaces and quantum scattering studies of NO( X  2Π) with He: Λ-doublet resolved rotational and electronic fine-structure transitions

New ab initio potential energy surfaces (PES’s) are presented for the interaction of He with the NO radical in its ground (X 2Π) electronic state, determined within the coupled electron pair approximation (CEPA) with a large atomic orbital basis set. The dynamics of the collisions of NO with He are then investigated, in particular the coupling between nuclear motion (rotation and translation) and the internal electronic motion of the open-shell partner. State-to-state integral and differential cross sections are calculated using full close coupling and coupled states methods. These cross sections are compared with the results of the two separate measurements at different initial collision energies, 508 and 1186 cm−1 (63 and 147 meV). Excellent agreement is obtained in both cases. Also comparisons with previous calculations, based on an earlier local density potential energy surface, are made at 508 and 2420 cm−1 (63 and 300 meV).