We report new experimental Fe i oscillator strengths obtained by combining measurements of branching fractions measured with a Fourier Transform spectrometer and time-resolved, laser-induced fluorescence lifetimes. This study covers the spectral region ranging from 213 to 1033 nm. A total of 120 experimental -values coming from 15 odd-parity energy levels are provided, 22 of which have not been reported previously and 63 of which have values with lower uncertainty than the existing data. The radiative lifetimes for 60 upper energy levels are presented, 39 of which have no previous measurements.

The lifetimes of 17 even-parity levels (3d5s, 3d4d, 3d6s, and 4p²) in the region 57743-77837 cm⁻¹ of singly ionised scandium (Sc ii) 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 Lawler and Dakin (1989) 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 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~ε_⊙ = 3.04 ± 0.13 using these semi-empirical oscillator strengths to shift the values determined by Scott et al. (2015). The new estimated abundance value is in agreement with the meteoritic value (log~ε_met = 3.05 ± 0.02) of Lodders et al. (2009).

We report a new study of the V i atom using a combination of time-resolved laser-induced fluorescence and Fourier transform spectroscopy that contains newly measured radiative lifetimes for 25 levels between 24,648 cm⁻¹ and 37,518 cm⁻¹ and oscillator strengths for 208 lines between 3040 and 20000 Å from 39 upper energy levels. Thirteen of these oscillator strengths have not been reported previously. This work was conducted independently of the recent studies of neutral vanadium lifetimes and oscillator strengths carried out by Den Hartog et al. and Lawler et al., and thus serves as a means to verify those measurements. Where our data overlap with their data, we generally find extremely good agreement in both level lifetimes and oscillator strengths. However, we also find evidence that Lawler et al. have systematically underestimated oscillator strengths for lines in the region of 9000 ± 100 Å. We suggest a correction of 0.18 ± 0.03 dex for these values to bring them into agreement with our results and those of Whaling et al. We also report new measurements of hyperfine structure splitting factors for three odd levels of V i lying between 24,700 and 28,400 cm⁻¹.

Intensified charge-coupled devices (ICCD) are used in a great variety of spectroscopic applications, some of them requiring high sensitivity and spectral resolution. The setup, configuration, and featuring of these cameras are fundamental issues in order to acquire high quality spectra. In this work a critical assessment of these detectors is performed and the specific configuration, the optical alignment, featuring, and the dark and shot noise are described and analyzed. Spatial response of the detector usually shows a significant lack of spatial homogeneity and a map of interferences may appear in certain ranges of wavelengths, which damages the quality of the recorded spectra. In this work the spectral resolution and the spatial and spectral sensitivity are also studied. The analysis of the dark current reveals the existence of a smooth but clear spatial dependence. As a final conclusion, the spectra registered with the spectrometer equipped with our ICCD camera allow us to explore and measure accurately spectral line shapes emitted by pulsed plasmas in the visible range and particularly in the ultraviolet (UV) range.

Accurate atomic parameters, such as transition probabilities, wavelengths, and energy levels, are indispensable for the analysis of stellar spectra and the obtainment of chemical abundances. However, the quantity and quality of the existing data in many cases lie far from the current needs of astronomers, creating an acute need for laboratory measurements of matching accuracy and completeness to exploit the full potential of the very expensively acquired astrophysical spectra. The Fourier Transform Spectrometer at Imperial College London works in the vacuum ultraviolet-visible region with a resolution of 2,000,000 at 200 nm. We can acquire calibrated spectra of neutral, singly, and doubly ionized species. We collaborate with the National Institute of Standards and Technology (NIST) and the University of Lund to extend our measurements into the infrared region. The aim of this review is to explain the current capabilities of our experiment in an understandable way to bring the astronomy community closer to the field of laboratory astrophysics and encourage further dialogue between our laboratory and all those astronomers who need accurate atomic data. This exchange of ideas will help us to focus our efforts on the most urgently needed data.

Transition probabilities have a significant interest in the astrophysical field. The aim of this experiment is to extend the present data base of measured Ar ii transition probabilities to the ultraviolet (UV) region and to improve the quality of some of the already existing data. Despite all the efforts made to assemble an accurate set of transition probabilities (A_ki), some of the data recommended by the National Institute of Standards and Technology (NIST) for Ar ii spectral lines in the UV region have uncertainties around 50 per cent. We measured relative intensities of spectral lines emitted from a low-pressure-pulsed discharge lamp which generates an argon plasma. Excitation temperatures of 19 000–22 000 K are determined from the Boltzmann-plot of 11 Ar ii spectral lines for which accurate A_ki data are available from the literature. The transition probabilities of these 11 spectral lines were used for calculating new A_ki-values. Electron densities (N_e) of 3.5–9.0 × 10²² m⁻³ are determined by two-wavelength interferometry method. The measurements yield to a collection of 43 atomic transition probabilities of Ar ii lines in the spectral region of 294–386 nm, 11 of which are new, at least up to the authors knowledge, and 22 improved A_ki-values for which the existing data in the literature have uncertainties around 50 per cent. Comparison with previous data shows how our measurements have good agreement with the most accurate A_ki-values from the bibliography, whereas some of the values recommended by NIST present a significant disagreement.