Experimental and theoretical radiative lifetimes, branching fractions and oscillator strengths for Lu I and experimental lifetimes for Lu II and Lu III

J.A. Fedchak, E.A. Den Hartog, J.E. Lawler, P. Palmeri, P. Quinet and E. Biémont

Astrophys. J. (in press, 2000)




Accurate radiative lifetimes from time-resolved laser-induced fluorescence measurements on a slow beam of lutetium atoms and ions are reported for 22 odd-parity levels and 4 even-parity levels of Lu I, and 14 odd-parity levels of Lu II. In addition, we report the radiative lifetime of one odd-parity level and an upper bound on the radiative lifetime of a second odd-parity level of Lu III. Experimental branching fractions for Lu I from emission spectra covering the near ultraviolet to the near infrared and recorded using the U.S. National Solar Observatory 1.0 m Fourier transform spectrometer are reported. The branching fractions are combined with the radiative lifetimes to produce 44 accurate, experimentally determined oscillator strengths for Lu I. New theoretical values for Lu I radiative lifetimes and branching fractions from a relativistic Hartree-Fock calculation which includes core polarization effects are also reported. These experimental and theoretical results, as well as older published results, are compared.


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