Collinear laser and slow-ion-beam apparatus for high-precision laser-rf double-resonance spectroscopy

A new apparatus has been constructed for high-precision hyperfine structure measurement of atomic ions by laser-radio-frequency double-resonance technique involving a slow ion beam and a laser in collinear geometry. The low ion energy (1--1.5 keV) leads to longer interaction time with the applied rf field. Consequently, extremely narrow linewidths of ∼60 kHz have been observed for the first time in such systems. The apparatus has been used for the measurement of hyperfine structure of the 4f7(8S0)5d9D0/sub 2,3,4,5/ metastable levels in 151Eu+ and 153Eu+. The magnetic dipole and the electric quadrupole hyperfine constants, A and B, respectively, have been determined with higher precision (2--3 orders of magnitude)