Precision Stark spectroscopy of sodium: Improved values for the ionization limit and bound states

Abstract

We report results of a combined theoretical and experimental investigation that uses Stark spectroscopy of high-lying Rydberg states to measure accurately zero-field atomic parameters. Improved values for the binding energies of the 11 $^{2}$S, 12 $^{2}$S, and ${10}^{2}$D states of sodium are presented. These results are combined with previous data in a global least-squares fit to obtain improved quantum-defect parameters for the sodium $^{2}$S and $^{2}$D manifolds. Using previous precision optical data, the present results, and the quantum-defect expansion, we obtain an improved value for the ionization limit of neutral sodium: ${\mathit{E}}_{\mathrm{ion}}$=41 449.451(2) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. The consequences of the improved ionization energy on the quantum-defect expansion parameters of the $^{2}$P states are also discussed and values are obtained from fits to the available data.