Atomic Transition Probabilities of Lanthanide Elements

Lawler，JamesAST-981900正在对选定的稀土元素TbII、EuII和LaII的谱线进行准确的绝对原子跃迁几率的实验室测量。恒星天文学家研究整个银盘和光晕中重元素的丰度模式，需要关于这些物种的数据。跃迁概率(g-f值)的不确定性是目前许多恒星丰度观测确定的最大不确定源。这些结果将在化学奇特恒星的研究中具有特别的价值。这些测量将通过将时间分辨激光诱导荧光得出的辐射寿命与傅里叶变换光谱辐射测量法获得的分支分数相结合来进行。随着时间的允许，GdII、YbII和LuII等其他稀土元素将被包括在研究中。

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.