Theoretical Evaluation of the Fractional Hyperfine Pressure Shift of Paramagnetic Atoms in a Noble Gas

The fractional hyperfine pressure shift (known as HPS in the literature) of paramagnetic atoms in an atmosphere of noble-gas atoms has been found to be computable quite adequately from recently evaluated extended-basis-set self-consistent-field molecular-orbital wave functions. The actual computation was carried out for lithium and sodium atoms in a helium buffer gas. Computed values of 78.87 ×{} 10^-9/mm Hg versus the experimental value of 77.7 ×{} 10^-9/mm Hg for LiHe and 78.11 versus 73.0 ×{} 10^-9/mm Hg for NaHe were obtained.