Precision Lamb-shift measurement in then=2state ofLi2+6

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 $\mathcal{S}=62\mathrm{}765\pm 21$ MHz, in good agreement with theory.