Oscillator strengths for high-excitation Ti ii from laboratory measurements and calculations

Abstract

This work reports new experimental radiative lifetimes of six 3d2(3F)5s levels in singly
\nionized titanium, with an energy around 63 000 cm−1 and four 3d2(3F)4p odd parity levels
\nwhere we confirm previous investigations. Combining the new 5s lifetimes with branching
\nfractions measured previously by Pickering et al., we report 57 experimental log gf values for
\ntransitions from the 5s levels. The lifetime measurements are performed using time-resolved
\nlaser-induced fluorescence on ions produced by laser ablation. One- and two-step photon
\nexcitation is employed to reach the 4p and 5s levels, respectively. Theoretical calculations
\nof the radiative lifetimes of the measured levels as well as of oscillator strengths for 3336
\ntransitions from these levels are reported. The calculations are carried out by a pseudo relativistic Hartree–Fock method taking into account core-polarization effects. The theoretical results are in a good agreement with the experiments and are needed for accurate abundance determinations in astronomical objects.