RADIATIVE LIFETIMES AND ATOMIC TRANSITION-PROBABILITIES

Radiative lifetimes and atomic transition probabilities have been meas ured for over 35 neutral and singly ionized species in the Wisconsin A tomic Transition Probabilities (WATP) Program since it began in 1980. Radiative lifetimes are measured using time-resolved laser-induced flu orescence of a slow atomic/ionic beam. These lifetimes are combined wi th branching fractions to yield absolute atomic transition probabiliti es for neutral and singly ionized species. The branching fractions are determined from emission spectra recorded using the 1.0 m Fourier-tra nsform spectrometer at the National Solar Observatory. The current foc us of the WATP Program is on the rare-earth elements, in particular Tm , Dy, and Po.