The lifetimes of 17 even-parity levels (3d5s, 3d4d, 3d6s and 4p2) in the region
57 743–77 837 cm−1 of singly ionized scandium (Sc II) were measured by two-step timeresolved
laser induced fluorescence spectroscopy. Oscillator strengths of 57 lines from these
highly excited upper levels were derived using a hollow cathode discharge lamp and a Fourier
transform spectrometer. In addition, Hartree–Fock calculations where both the main relativistic
and core-polarization effects were taken into account were carried out for both low- and
high-excitation levels. There is a good agreement for most of the lines between our calculated
branching fractions and the measurements of Lawler & Dakin in the region 9000–45 000 cm−1
for low excitation levels and with our measurements for high excitation levels in the region
23 500–63 100 cm−1. This, in turn, allowed us to combine the calculated branching fractions
with the available experimental lifetimes to determine semi-empirical oscillator strengths for
a set of 380 E1 transitions in Sc II. These oscillator strengths include the weak lines that were
used previously to derive the solar abundance of scandium. The solar abundance of scandium
is now estimated to log = 3.04 ± 0.13 using these semi-empirical oscillator strengths to
shift the values determined by Scott et al. The new estimated abundance value is in agreement
with the meteoritic value (logmet = 3.05 ± 0.02) of Lodders, Palme & Gail.