HYPERFINE-STRUCTURE MEASUREMENTS IN THE S-7(3) METASTABLE FINE-STRUCTURE LEVEL IN STABLE AND UNSTABLE EU+ ISOTOPES

Clouds of stable and unstable Eu+ isotopes have been confined in a Pau l trap, each containing about 10(5) particles. In a microwave-optical double resonance experiment several hyperfine separations in the 4f(7) 6s S-7(3) exited level have been measured with the experimental uncer tainties ranging between 10(-8) and 3 x 10(-6). These experiments have confirmed that also in the case of an excited level with a large numb er of hyperfine or Zeeman sublevels the microwave-optical double reson ance technique in a Paul trap can be useful for precise hyperfine stru cture investigation. The hyperfine coupling constants A and B have bee n determined for the isotopes Eu-153(+), Eu-151(+), Eu-150(+) and Eu-1 48(+). The results complement earlier measurements on the ground state of Eu+ and give additional information on the hyperfine anomaly in th e Eu isotopic chain.