Radiative lifetime measurements and semi-empirical transition parameter calculations for high-lying levels in Ba I

Abstract

Radiative lifetimes for 18 highly excited levels belonging to 5d4f, 5d6p, and 6snp (n = 10, 12, 14–19) configurations of barium were measured by time-resolved laser-induced fluorescence (TR-LIF) technique. The uncertainties of the results are less than 10%. To our best knowledge, there are 16 lifetimes of Ba I reported for the first time. Two lifetimes were measured to compare with the previous results, and good agreements were achieved. From the combination of these experimental lifetimes and theoretical branching fractions calculated using a pseudo-relativistic Hartree–Fock model including core-polarization effects, a set of semi-empirical transition probabilities and oscillator strengths was derived for 46 Ba I spectral lines in the wavelength region from 240 to 3765 nm. For about half of these transitions, the uncertainties affecting the new decay parameters were found to be equal or better than 50%.