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

TL;DR

This paper reports laboratory measurements of transition probabilities and radiative lifetimes for Cr II lines, providing accurate data crucial for astrophysical and spectroscopic applications.

Contribution

It presents new, precise laboratory measurements of 145 Cr II transition probabilities and 14 lifetimes, improving upon previous semi-empirical and experimental data.

Findings

Measured 145 Cr II transition probabilities.

Determined radiative lifetimes for 14 Cr II levels.

Compared results with existing semi-empirical calculations.

Abstract

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 68000 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 Cr II lines and radiative lifetimes for 14 Cr II levels. The laboratory-measured transition probabilities are compared to the values from semi-empirical calculations and laboratory measurements in the literature.