Stimulated Raman measurements of the hyperfine structure in Yii

Stimulated Raman spectroscopy has been used in a fast ion beam to measure the hyperfine structure in the 4${\mathit{d}}^2$ configuration of Y i i. A simple theory is provided for the line shape of the coherent two-photon transition which gives a transit-time limited linewidth of 0.9/T, comparable to the resolution of the laser–radio-frequency double-resonance technique. The hyperfine structure is compared with a multiconfiguration Dirac-Fock calculation and with that of the homologous Sc i i ion. This comparison confirms the role of core polarization as a significant factor in the hyperfine structure of these ions.