The FERRUM project: laboratory-measured transition probabilities for ^*

¹ Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden e-mail: jonas.gurell@fysik.su.se
² Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden
³ Atomic Physics, Department of Physics, Lund University, Box 118, 22100 Lund, Sweden
⁴ Catholic University of America, Washington, DC 20064, USA
⁵ Astrophysics Science Division, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771, USA

Received: 16 November 2009
Accepted: 15 December 2009

Abstract

Aims. We measure transition probabilities for transitions from the z ⁴H, z ²D, y ⁴F, and y ⁴G levels in the energy range 63 000 to 68 000 cm^-1.

Methods. Radiative lifetimes were measured using time-resolved laser-induced fluorescence from a laser-produced plasma. In addition, branching fractions were determined from intensity-calibrated spectra recorded with a UV Fourier transform spectrometer. The branching fractions and radiative lifetimes were combined to yield accurate transition probabilities and oscillator strengths.

Results. We present laboratory measured transition probabilities for 145 lines and radiative lifetimes for 14 levels. The laboratory-measured transition probabilities are compared to the values from semi-empirical calculations and laboratory measurements in the literature.