New term in atomic Zeeman energy

Abstract

An unexpected Zeeman shift discovered in recent measurements of ground-state rubidium hyperfine structure in strong magnetic fields can be explained as an effect of the hyperfine interaction in the mixing of electronic states of different principal quantum number and spin direction into the ground state. A term of the form \ensuremath{\beta}${\mathrm{m}}_{\mathrm{I}}^{2}$${\mathrm{M}}_{\mathrm{J}}$B/J is induced in the ground-state energy. A calculation based on the Fermi-Segr\'e treatment of alkali-metal atoms yields the theoretical values \ensuremath{\beta}${(\mathrm{}}^{85}$Rb)=0.016 Hz/T and \ensuremath{\beta}${(\mathrm{}}^{87}$Rb)=0.18 Hz/T, which are in good agreement with the experimental results: \ensuremath{\beta}${(\mathrm{}}^{85}$Rb)=0.0162(14) Hz/T and \ensuremath{\beta}${(\mathrm{}}^{87}$Rb)=0.168(15) Hz/T.