The Ne–N2 potential energy surface from high-resolution total differential scattering experiments and a close-coupling and infinite-order-sudden analysis

Abstract

High-resolution crossed molecular beam measurements of the total differential cross section (DCS) for the scattering of Ne by N2 at a collision energy of E=75.8 meV are reported. Strongly quenched diffraction oscillations superimposed on the falloff of the main rainbow structure are clearly resolved. A reliable Ne–N2 potential energy surface (PES) is derived by simultaneously fitting second virial, diffusion, and viscosity coefficient data taken from the literature. Information on the anisotropy of the interaction is obtained from the quenching of the diffraction oscillations in the total DCS within the framework of the infinite-order-sudden (IOS) approximation. The reliability of the IOS approximation in deriving a fully anisotropic potential energy surface from the measured scattering dynamics is examined and demonstrated by performing exact close-coupling calculations for the present experimental conditions and then comparing both integral and differential total and rotationally inelastic cross sections. The derived PES is compared with recently proposed theoretical model potential surfaces. Although in satisfactory agreement with bulk properties, none of these surfaces predicts correctly the present scattering data, each having significantly different spherical and/or anisotropic components in comparison with the PES derived here.