RELATIVISTIC TRANSITION-PROBABILITIES AND LIFETIMES OF LOW-LYING LEVELS IN YTTERBIUM

Multiconfiguration Dirac-Fock calculations of E1, E2, M1 and M2 transition probabilities and lifetimes for the low-lying levels of neutral ytterbium are reported. For E1 transitions the valence-core electron correlations are also included in the core-polarization model. In particular, the lifetimes of the 6s6p 1P1 and 3P1 states, when corrected for core polarization, are found to be 4.78 ns and 1294 ns, respectively. The lifetime of the metastable 6s6p 3P2 state is calculated to be 14.5 s.