The lifetimes of 17 even-parity levels ( 3d5s , 3d4d , 3d6s , and 4p ^ { 2 } ) in the region 57743-77837 cm ^ { -1 } of singly ionised scandium ( \ion Scii ) were measured by two-step time-resolved 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-polarisation 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 \citet law89 in the region 9000-45000 cm ^ { -1 } for low excitation levels and with our measurements for high excitation levels in the region 23500-63100 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 \ion Scii .
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 } ~ { } \epsilon _ { \sun } = 3.04 \pm 0.13 using these semi-empirical oscillator strengths to shift the values determined by \citet sco15 .
The new estimated abundance value is in agreement with the meteoritic value ( { log } ~ { } \epsilon _ { \text { met } } = 3.05 \pm 0.02 ) of \citet lod09 .