Interatomic potentials for HeAr, HeKr, and HeXe from multiproperty fits

Crossed molecular beam measurements of differential cross sections (DCS) are reported for elastic scattering of He by Ar, Kr, and Xe at high resolution. Interatomic potentials are determined by simultaneously fitting the DCS's, as well as mixture viscosity and interaction second virial data. Bias due to systematic and potential model errors are examined and are used to estimate the accuracy of the potential energy curves obtained. Attractive well depths are 2.59, 2.67, and 2.64 meV ± 3% for HeAr, HeKr, and HeXe, respectively, agreeing with the best available HeAr potential and a previously proposed HeKr potential, but significantly deeper than previously reported potentials for HeXe. The HeXe attractive well is also considerably broader than previously reported. Attractive minimum positions are 3.48, 3.70, and 4.00 Å (±0.03 Å) for HeAr, HeKr, and HeXe, respectively. Including the accurate diffusion data of Dunlop and co-workers [Physica A 95, 561 (1979)] and the absolute integral cross sections of Pirani and Vecchiocattivi [J. Chem. Phys. 66, 372 (1977) and revisions thereto] verify the error bounds for all three potentials.