The pure rotational spectrum of the ScO (X2Σ+) radical

D. T. Halfen, J. Min, L. M. Ziurys

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The rotational spectrum of ScO (X2Σ+) has been measured in the gas phase in the frequency range 30–493 GHz using a combination of Fourier transform microwave/millimeter-wave (FTM/mmW) and submillimeter direct absorption methods. This work is the first pure rotational study of this radical. Both the ground vibrational and v = 1 states were observed. ScO was created from the reaction of metal vapor, produced either by a laser ablation source or a Broida-type oven, and N2O, in the former case heavily diluted in argon. Extensive hyperfine structure was observed in the FTM/mmW data, although the spin-rotation splitting was found to be small (∼3 MHz). In the mm-wave spectra, however, the fine and hyperfine structure was blended together, resulting in broad, single lines for a given transition N + 1 ← N. The data were analyzed in a combined fit using the very accurate hyperfine measurements of Childs and Steimle (1988), employing a Hund's case b Hamiltonian, and an improved set of rotational and centrifugal distortion constants were determined. These measurements improve the accuracy of predicted frequencies for astronomical searches by 14–18 MHz, or 16–20 km/s, in the 1 mm region – a difference of half to a full linewidth for certain interstellar sources. This work also demonstrates the capabilities of the FTM/mmW spectrometer at 61 GHz.

Original languageEnglish (US)
Pages (from-to)1-5
Number of pages5
JournalJournal of Molecular Spectroscopy
StatePublished - Jan 1 2017


  • FTM/mmW spectroscopy
  • Laser ablation
  • Millimeter/submillimeter direct absorption spectroscopy
  • Rotational spectroscopy
  • Scandium oxide (ScO)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Spectroscopy
  • Physical and Theoretical Chemistry


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