The pure rotational spectrum of VS (X4Σ−): A combined Fourier transform microwave and millimeter-wave study

• Published in: Journal of molecular spectroscopy Vol. 290; pp. 42 - 47
• Main Authors: Adande, G.R., Ziurys, L.M.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.08.2013
• Subjects: FTMW spectroscopy; Hyperfine structure; Laser ablation; Millimeter wave spectroscopy; Vanadium sulfide (VS); Hyperfine structure; Millimeter wave spectroscopy; Laser ablation; FTMW spectroscopy; Vanadium sulfide (VS)
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1016/j.jms.2013.07.002

[Display omitted] •Measured rotational spectra of VS (X4Σ+) with direct absorption millimeter wave and FTMW/laser ablation methods.•Accurate bond length obtained for VS for examination of periodic trends.•Hyperfine constants suggest V–S bond more covalent than O analogs.•Fine structure constants provide estimates on position of two low lying excited states. The pure rotational spectrum of the vanadium sulfide radical, VS (X4Σ−), has been measured in the frequency range 5–310GHz using a combination of millimeter-wave direct absorption and Fourier transform microwave (FTMW) techniques. In the millimeter-wave region, the radical was produced in an AC discharge from the reaction of VCl4, the vanadium donor, and CS2. In the FTMW instrument, the molecule was created in a supersonic jet, coupled with a laser ablation/DC discharge source (DALAS), from a mixture of metal vapor and H2S, heavily diluted in argon. A total of 8 rotational transitions were measured for VS, in which both the quartet fine structure and vanadium hyperfine splittings were resolved. The spectra were analyzed with a Hund’s case (b) Hamiltonian, and rotational, spin–rotation, spin–spin, and hyperfine parameters were determined. The precision of the constants from previous optical studies was refined and, for the first time, the vanadium quadrupole constant, eQq=−7.6 (4.0)MHz, and the third order Fermi contact correction, bS=−0.293 (94)MHz, were established. From the fine structure parameters, the nearby 4Π and 2Σ+ states were estimated to lie ∼6560cm−1 and ∼7170cm−1 above the ground state. The hyperfine constants suggest that the bonding in VS is partly ionic, with a significant degree of covalent character.