Hyperfine structure of 151,153Eu+ in the state 4f7(8So)5d 9D4o by collinear laser-rf double resonance.

Abstract

An apparatus has been constructed for laser--radio-frequency double-resonance studies of very-low-energy-ion beams with collinear laser-ion geometry. The ion energy of only 1--2 keV leads to extremely narrow linewidths (\ensuremath{\sim}60 kHz). This paper describes measurements of the hyperfine structure of $^{151}\mathrm{Eu}^{+}$ and $^{153}\mathrm{Eu}^{+}$ in the level 4${f}^{7}$(${}^{8}$${S}^{o}$)5d ${}^{9}$${D}_{4}^{o}$. The hyperfine constants A and B have been determined with a much higher accuracy than before. The present values of these constants (in MHz) are =113.159(1), =-215.356(10), =-50.415(1), =-548.357(10). .AE