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Infrared emission spectra of candidate interstellar aromatic moleculesInterstellar dust is responsible, through surface reactions, for the creation of molecular hydrogen, the main component of the interstellar clouds in which new stars form. Intermediate between small, gas-phase molecules and dust are the polycyclic aromatic hydrocarbons (PAHs). Such molecules could account for 2-30% of the carbon in the Galaxy, and may provide nucleation sites for the formation of carbonaceous dust. Although PAHs have been proposed as the sources of the unidentified infrared emission bands that are observed in the spectra of a variety of interstellar sources, the emission characteristics of such molecules are still poorly understood. Here we report laboratory emission spectra of several representative PAHs, obtained in conditions approximating those of the interstellar medium, and measured over the entire spectral region spanned by the unidentified infrared bands. We find that neutral PAHs of small and moderate size can at best make only a minor contribution to these emission bands. Cations of these molecules, as well as much larger PAHs and their cations, remain viable candidates for the sources of these bands.
Document ID
20040173250
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Schlemmer, S.
(University of California Berkeley 94720-1460, United States)
Balucani, N.
Wagner, D. R.
Steiner, B.
Saykally, R. J.
Date Acquired
August 22, 2013
Publication Date
March 21, 1996
Publication Information
Publication: Nature
Volume: 380
Issue: 6571
ISSN: 0028-0836
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Exobiology
NASA Program Exobiology
NASA Discipline Number 52-10

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