Pseudopotential analysis on hyperfine splitting frequency shift of alkali-metal atoms in noble gases, revisited.

This article focuses on the theoretical analysis of ground-state hyperfine splitting frequency shifts of alkali-metal atoms (Li, Na, K, Rb, Cs) in noble gases (He, Ne, Ar, Kr, Xe) using pseudopotentials and dispersion potentials. Employing first-order perturbation theory with a single fitting parameter, the study qualitatively reproduces the temperature dependence of measured frequency shifts across all atom pairs and relates these shifts to noble-gas properties such as the s-wave electron scattering length, electric-dipole polarizability (α), and van der Waals radius (Rw). The analysis introduces a comprehensive equation linking the pseudopotential height (ah), fitting energy parameter (E_fit), α, Rw, and a characteristic energy (Ec) of the colliding pairs, demonstrating that heavier alkali-metal atoms, in addition to lithium, can effectively probe noble-gas characteristics. The work also suggests that improvements in excitation energies and dispersion potentials, particularly for helium and neon, could enhance the accuracy of such theoretical models.