Atomic clock with nuclear transition: current status in TU Wien
  The nucleus of 229Thorium presents a unique isomer state of very low energy and long lifetime, current estimates are around 7.8 eV and seconds to hours respectively. This nuclear transitions therefore is a promising candidate for a novel type of frequency standard and several groups worldwide have set out to investigate this system. Our aim is to construct a "solid state nuclear clock", i.e. a frequency standard where Thorium ions are implanted into Calciumfluoride crystals transparent in vacuum ultraviolet range. As a first step towards an accurate determination of the exact energy and lifetime of this isomer state we perform low-resolution fluorescent spectroscopic measurements. 
G. A. Kazakov, M. Schreitl, G. Winkler, J. H. Sterba, G. Steinhauser   and T. Schumm
physics.atom-ph