The spectrum of V v has been observed by using a vacuum sliding spark at 1000-A peak current. Fifty-nine lines in the region 480–8500 Å have been observed and interpreted as transitions among 29 levels, 19 of which are new. The ionization energy is determined as 526 524 ± 5 cm<sup>-1</sup>. An isoelectronic comparison confirms the inversion of the 3<i>p</i><sup>6</sup>4ƒ<sup>2</sup><i>F</i><sub>5/2, 7/2</sub>° levels as being caused by their interaction with those of the <sup>2</sup><i>F</i>° term in the 3<i>p</i><sup>5</sup> 3<i>d</i><sup>2</sup> configuration.
Cornelius H. H. Van Deurzen, John G. Conway, and Sumner P. Davis, "Spectrum and energy levels of quadrupole-ionized vanadium (V v)," J. Opt. Soc. Am. 64, 498-502 (1974)