Experimental isotope shifts of the 5 2S1/2state and low-lying excited states of Rb

Abstract

By combining a recent precise measurement of the ionization energy of ${}^{87}$Rb with previous measurements of the ground-state hyperfine structure and ionization energy of ${}^{85}$Rb, an accurate value for the ${}^{85}\text{Rb}{\ensuremath{-}}^{87}\text{Rb}$ isotope shift of the 5 ${}^{2}\phantom{\rule{-0.16em}{0ex}}{S}_{1/2}$ ground state can be determined. In turn, comparison with additional spectroscopic data makes it possible to evaluate isotope shifts for the low-lying excited states, which are accurate in most cases to about 1 MHz. For the 5 ${}^{2}\phantom{\rule{-0.16em}{0ex}}{S}_{1/2}$ and 5 ${}^{2}\phantom{\rule{-0.16em}{0ex}}{P}_{3/2}$ states, the specific mass-shift contribution can be determined in addition to the total shift. This information is particularly useful for spectroscopic analysis of transitions to Rydberg states and for tests of atomic theory.