Experimental radiative lifetimes, branching fractions, and oscillator strengths of Ta I levels

Abstract

Radiative lifetimes for 20 levels of Ta I in the energy range of 30 664.66–43 550.78 cm−1 were measured by the time-resolved laser-induced fluorescence technique. Among the results, to our knowledge, 17 lifetimes are reported for the first time. These lifetime values are in the range from 8.5–97 ns. A good agreement is achieved between the present and previously reported results. Branching fractions (BFs) of 97 transitions related to 13 of these levels were determined from the emission spectra of hollow cathode lamps recorded by the Fourier transform spectrometer at the National Solar Observatory on Kitt Peak, USA, available from digital library (http://diglib.nso.edu/ftp.html). By combining these BFs with our lifetime results, absolute transition probabilities and oscillator strengths for these lines were obtained.