Laboratory detection of FeCO+ (X4Σ-) by millimeter/submillimeter velocity modulation spectroscopy

D. T. Halfen, L. M. Ziurys

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The millimeter/submillimeter spectrum of the molecular ion FeCO+ (X4Σ-) has been recorded using velocity modulation spectroscopy. The molecular ion was created in an AC discharge of Fe(CO) 5 and argon. Twentyseven rotational transitions, each consisting of four fine-structure components, were measured in the range 198-418 GHz. The data were fit with a case b Hamiltonian, and rotational, spin-rotation, and spin-spin constants were determined. Because of the presence of higher order spin-orbit interactions, probably caused in part by a nearby 4II excited state, numerous centrifugal distortion terms were needed for the spectral analysis. The value of γs, the third-order spin-rotation constant, was also remarkably large at -72.4 MHz. Rest frequencies for FeCO+ are now available for interstellar and circumstellar searches. This species may be present in molecular clouds, where CO is abundant and gas-phase iron should be in the form of Fe+. Molecular ions such as FeCO+ could be the hidden carriers of metallic elements in such clouds.

Original languageEnglish (US)
Pages (from-to)L61-L64
JournalAstrophysical Journal
Issue number1 II
StatePublished - Mar 1 2007


  • Astrochemistry
  • ISM: molecules
  • Line: identification
  • Methods: laboratory
  • Molecular data
  • Stars: AGB and post-AGB

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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