Laboratory measurements of accurate absolute atomic transition probabilities for the spectral lines of selected lanthanide "rare earth" elements TbII, EuII and LaII are being made. Stellar astronomers studying the abundance patterns of heavy elements throughout the Galactic disk and halo need data on these species. It is the uncertainty in transition probabilities (g-f values) which contribute the largest single source of uncertainty to many current observational determinations of stellar abundance. These results will be of particular value in studies of chemically peculiar stars. The measurements will be made by combining radiative lifetimes derived from time-resolved laser-induced fluorescence with branching fractions obtained from Fourier transform spectroradiometry. As time permits other lanthanide elements such as GdII, YbII and LuII will be included in the study.
