Lifetime measurements in Ce I, Ce II, and Ce III using time-resolved laser spectroscopy with application to stellar abundance determinations of cerium

Abstract

Radiative lifetimes of two levels in Ce I, eight levels in Ce II, and nine levels in Ce III have been measured using the time-resolved laser-induced fluorescence technique. Free cerium atoms and singly and doubly ionized ions were obtained in a laser-produced plasma. A narrow bandwidth UV laser pulse was employed to selectively populate the short-lived upper levels and the lifetime values were evaluated from the time-resolved fluorescence signals recorded by a fast detection system. Transition probabilities for Ce III were obtained from branching fractions calculated by the Cowan code and the experimental lifetimes. The results are compared with previous measurements and calculations. Spectral lines of Ce III were identified in the spectrum of the magnetic chemically peculiar star ${\ensuremath{\alpha}}^{2}\mathrm{CVn}$ and the abundance of cerium was determined from synthetic spectrum fitting to be 800 times greater than the solar abundance.