He--O2 anisotropic van der Waals potential from the interplay of theory and scattering experiments

The interaction of helium atoms with ground state O2 molecules is examined over a wide range of internuclear distances that fully sample the extension of the shallow well region. A previous multiproperty study of its spherical part is extended to obtain the shape of its anisotropic behavior accurately by a best-fit procedure which involves very precise state-to-state measurements of rotationally inelastic cross sections and IOSA calculations of total and partial differential cross sections. The final form of the interaction is discussed and analyzed with respect to previous findings for similar systems