Precision Microwave Spectroscopy on Trapped Ions

By use of the microwave-optical double resonance technique high precision values of hyperfine splitting constants of ions, confined electrodynamically in traps, have been obtained in recent years. Improved sensitivity has made possible the first investigation of unstable isotopes of Ba + which are available in minute quantities only. The precision is similar as for the stable isotopes and represents a first step to a systematic study of the Bohr-Weißkopf-effect in chains of isotopes. Furthermore the possibility of g J -factor measurements in the hydrogen molecular ion is discussed and first results are presented which may lead to a determnation of QED- and relativistic corrections in the most elementary molecule.