Flying characterization of colliding partners by hyperfine splitting frequency of neutral paramagnetic atoms.

The pseudopotentials and dispersion potentials are applied to a theoretical study of the hyperfine splitting frequencies of the ground-state paramagnetic hydrogen (H) and alkali-metal (Li, Na, K, Rb, and Cs) atoms in noble gases (He, Ne, Ar, Kr, and Xe). Using classical turning points for statistical averages, we find that numerical calculations based on second-order perturbation theory fit the measured frequency shifts well over a wide temperature range. The characteristic energy, pseudopotential height, and electric-dipole polarizability allow us to consistently determine the van der Waals radii and electron scattering lengths of noble-gas atoms. This study shows that the hyperfine splitting frequency of alkali-metal atoms is a good measure for investigating colliding partners.