Laboratory optical spectroscopy of the thiophenoxy radical and its profile simulation as a diffuse interstellar band based on rotational distribution by radiation and collisions

Mitsunori Araki, Kei Niwayama, Koichi Tsukiyama

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The gas-phase optical absorption spectrum of the thiophenoxy radical (C6H5S), a diffuse interstellar band (DIB) candidate molecule, was observed in the discharge of thiophenol using a cavity ringdown spectrometer. The ground-state rotational constants of the thiophenoxy radical were theoretically calculated, and the excited-state rotational constants were determined from the observed rotational profile. The rotational profile of a near prolate molecule having C2v symmetry was simulated on the basis of a rotational distribution model by radiation and collisions. Although the simulated profile did not agree with the observed DIBs, the upper limit of the column density for the thiophenoxy radical in the diffuse clouds toward HD 204827 was evaluated to be 2 × 1013 cm-2. The profile simulation indicates that rotational distribution by radiation and collisions is important to reproduce a rotational profile for a DIB candidate and that the near prolate C2v molecule is a possible candidate for DIB with a band width variation dependent on the line of sight.

Original languageEnglish
Article number87
JournalAstronomical Journal
Volume148
Issue number5
DOIs
Publication statusPublished - 1 Nov 2014

Keywords

  • ISM: clouds
  • ISM: lines and bands
  • ISM: molecules
  • astrochemistry

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