Experimentally Measured Radiative Lifetimes and Oscillator Strengths in Neutral Vanadium

Abstract

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 .

Vanadium Transitions in the Spectrum of Arcturus

“…Lawler et al (2014;hereafter La14) reported new transition probabilities for 836 V I lines. Recently, Holmes et al (2016;hereafter Ho16) have also determined transition probabilities for 208 lines of this species. For most lines in common between these two studies the results are in good agreement, but Ho16 suggest that the La14 log(gf) values are systematically too small for six lines in common near 900 nm.…”

Laboratory transition probabilities for studies of nucleosynthesis of Fe-group elements1

“…The resulting log(gf)s for V I confirmed a good Saha balance for V in the Sun and HD 84937 [58]. A recent challenge by Holmes et al [59] to the BFs and log(gf)s for six of the 836 lines in Lawler et al [58] is under review. The tentative conclusions of the review confirmed the accuracy of Ar I branching ratios [60] used for calibration of FTS data and support the accuracy of the log(gf)s in Lawler et al [58].…”

Recent advances in experimental laboratory astrophysics for stellar astrophysics applications and future data needs

“…The subsequent term analysis led to 544 accurate energy levels, of which 89 were new, found for the first time (Thorne et al 2011). We also measured transition probabilities for 208 lines in the range 304-2000 nm from 39 upper levels by combining our FTS measured relative line intensities and atomic level lifetimes, measured at Lund laser centre, (Holmes et al 2016), increasing the number of laboratory loggf s available at longer wavelengths. V II -our published linelist includes 1242 classified lines in the 149-580 nm range from FT spectra.…”