Optical Excitation and Decay Dynamics of Ytterbium Atoms Embedded in a   Solid Neon Matrix
  Neutral ytterbium atoms embedded in solid neon qualitatively retain the structure of free atoms. Despite the atom-solid interaction, the 6s6p $^3$P$_0$ level is found to remain metastable with its lifetimes determined to be in the range of ten to hundreds of seconds. The atomic population can be almost completely transferred between the ground level and the metastable level via optical excitation and spontaneous decay. The dynamics of this process is examined, and is used to explicitly demonstrate that the transition broadening mechanism is homogeneous. 
C.-Y. Xu, S.-M. Hu, J. Singh, K. Bailey, Z.-T. Lu, P. Mueller, T. P.   O'Connor and U. Welp
physics.atom-ph