Atomic Transition Probabilities of Lanthanide Elements

Lawler，JamesAST-9819400实验室正在对选定的镧系“稀土”元素TbII、EuII和LaII的光谱线进行精确的绝对原子跃迁几率测量。 恒星天文学家研究整个银河系盘和晕的重元素丰度模式需要这些物种的数据。 跃迁概率（g-f值）的不确定性是目前许多恒星丰度观测测定中最大的不确定性来源。 这些结果对研究化学性质特殊的恒星具有特别的价值。 测量将通过结合辐射寿命从时间分辨的激光诱导荧光与分支分数从傅里叶变换光谱辐射。 随着时间的推移，其他镧系元素，如Gd II，Yb II和LuII将被纳入研究。

ABSTRACTLawler, JamesAST-9819400Laboratory 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.