Peripherally hydrogenated neutral polycyclic aromatic hydrocarbons as carriers of the 3 micron interstellar infrared emission complex: Results from single-photon infrared emission spectroscopy

D. R. Wagner, Hacksung Kim, R. J. Saykally*

*Corresponding author for this work

Research output: Contribution to journalArticle

52 Scopus citations

Abstract

Infrared emission spectra of five gas-phase UV laser-excited polycyclic aromatic hydrocarbons (PAHs) containing aliphatic hydrogens are compared with the main 3.3 μm and associated interstellar unidentified infrared emission bands (UIRs). We show that neutral PAHs can account for the majority of the 3 μm emission complex while making little contribution to the other UIR bands; peripherally hydrogenated PAHs produce a better match to astrophysical data than do those containing methyl side groups; 3.4 μm plateau emission is shown to be a general spectral feature of vibrationally excited PAHs containing aliphatic hydrogens, especially those containing methyl groups; and finally, hot-band and overtone emissions arising from aromatic C-H vibrations are not observed in laboratory emission spectra, and therefore, in contrast to current assignments, are not expected to be observed in the UIRs.

Original languageEnglish (US)
Pages (from-to)854-860
Number of pages7
JournalAstrophysical Journal
Volume545
Issue number2 PART 1
DOIs
StatePublished - Dec 20 2000

Keywords

  • ISM: lines and bands
  • ISM: molecules
  • Infrared: ISM: lines and bands
  • Molecular data
  • Molecular processes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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