Scalar polarizabilities and avoided crossings of high Rydberg states in Rb.

Abstract

Two-photon Doppler-free spectroscopy has been used to measure Stark shifts of $n^{2}S$ Rydberg states of $^{85}\mathrm{Rb}$ (for $n=15 \mathrm{to} 80$). Scalar polarizabilities ${\ensuremath{\alpha}}_{0}$ were found to obey the relation ${\ensuremath{\alpha}}_{0}[\mathrm{in}\mathrm{MHz}/{(\mathrm{V}/\mathrm{cm})}^{2}]=2.202(28)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}{n}^{*6}+5.53(13)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}{n}^{*7}$, in good agreement with theoretical values. Avoided crossings were also determined, and first avoided crossings (with the $n\ensuremath{-}3$ manifold of levels) fitted the relation $E(\mathrm{in}\mathrm{V}/\mathrm{cm})=4.638(6)\ifmmode\times\else\texttimes\fi{}\frac{{10}^{8}}{{n}^{*5}}+1.528(18)\ifmmode\times\else\texttimes\fi{}\frac{{10}^{10}}{{n}^{*7}}$.