The FERRUM project: laboratory-measured transition probabilities for Cr II

摘要

Aims: We measure transition probabilities for Cr II transitions from the z^4H_J, z ^2D_J, y ^4F_J, and y ^4G_J levels in the energy range 63000 to 68000cm^{-1}. Methods: Radiative lifetimes were measured using time-resolvedlaser-induced fluorescence from a laser-produced plasma. In addition, branchingfractions were determined from intensity-calibrated spectra recorded with a UVFourier transform spectrometer. The branching fractions and radiative lifetimeswere combined to yield accurate transition probabilities and oscillatorstrengths. Results: We present laboratory measured transition probabilities for145 Cr II lines and radiative lifetimes for 14 Cr II levels. Thelaboratory-measured transition probabilities are compared to the values fromsemi-empirical calculations and laboratory measurements in the literature.