Precision Lamb-Shift Measurement in then=2State ofLi2+6

Abstract

A microwave-optical pulsing and trapping technique has been employed to observe Lamb-shift ($\mathcal{S}=2\mathrm{}{S}_{\frac{1}{2}}\to 2P_{\frac{1}{2}}$) transitions in ${}_{}{}^6{}_{}{}^{}\mathrm{Li}_{}^{2+}{}_{}{}^{}$. Microwave transitions were induced in trapped metastable ${\mathrm{Li}}^{2+}\left(2\mathrm{}{S}_{\frac{1}{2}}\right)$ ions produced beforehand by a pulsed electron beam incident upon a low-pressure lithium vapor. Resonances were observed in the soft x-ray decay light as an applied magnetic field was swept through the Zeeman transition frequency. Computer fitting of 76 line centers yields $\mathcal{S}=62765\mathrm{}\pm 21$ MHz in good agreement with theory.