Radiative lifetimes and transition probabilities in Ta I

Radiative lifetimes of 14 odd-parity Ta I levels, belonging to the 5d36s6p and 5d46p configurations in the energy range from 30 664 to 45 256 cm-1, have been measured using the time-resolved laser-induced fluorescence technique. Extensive calculations, taking configuration interactions and core-polarisation effects into account, are able to reproduce in a satisfying way the available experimental results but suffer from the rather fragmentary knowledge of the level structure of this atom. New transition probabilities are deduced for a set of strong lines depopulating the levels investigated experimentally in the present work.