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Article: On The Origin Of The 3.3 Micron Unidentified Infrared Emission Feature

TitleOn The Origin Of The 3.3 Micron Unidentified Infrared Emission Feature
Authors
KeywordsISM: lines and bands
ISM: molecules
Issue Date2017
PublisherAmerican Astronomical Society, co-published with Institute of Physics Publishing, Inc. The Journal's web site is located at http://iopscience.iop.org/0004-637X/
Citation
The Astrophysical Journal, 2017, v. 845 n. 2, p. 123:1-13 How to Cite?
AbstractThe 3.3 micron unidentified infrared emission feature is commonly attributed to C-H stretching band of aromatic molecules. Astronomical observations have shown that this feature is composed of two separate bands at 3.28 and 3.30 micron and the origin of these two bands is unclear. In this paper, we perform vibrational analyses based on quantum mechanical calculations of 153 organic molecules, including both pure aromatic molecules and molecules with mixed aromatic/olefinic/aliphatic hybridizations. We found that many of the C-H stretching vibrational modes in polycyclic aromatic hydrocarbon (PAH) molecules are coupled. Even considering the un-coupled modes only, the correlation between the band intensity ratios and the structure of the PAH molecule is not observed and the 3.28 and 3.30 micron features cannot be directly interpreted in the PAH model. Based on these results, the possible aromatic, olefinic and aliphatic origins of the 3.3 micron feature are discussed. We suggest that the 3.28 micron feature is assigned to aromatic C-H stretch whereas the 3.30 micron feature is olefinic. From the ratio of these two features, the relative olefinic to aromatic content of the carrier can be determined.
Persistent Identifierhttp://hdl.handle.net/10722/243070
ISSN
2023 Impact Factor: 4.8
2023 SCImago Journal Rankings: 1.905
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorSadjadi, S-
dc.contributor.authorZhang, Y-
dc.contributor.authorKwok, S-
dc.date.accessioned2017-08-25T02:49:34Z-
dc.date.available2017-08-25T02:49:34Z-
dc.date.issued2017-
dc.identifier.citationThe Astrophysical Journal, 2017, v. 845 n. 2, p. 123:1-13-
dc.identifier.issn0004-637X-
dc.identifier.urihttp://hdl.handle.net/10722/243070-
dc.description.abstractThe 3.3 micron unidentified infrared emission feature is commonly attributed to C-H stretching band of aromatic molecules. Astronomical observations have shown that this feature is composed of two separate bands at 3.28 and 3.30 micron and the origin of these two bands is unclear. In this paper, we perform vibrational analyses based on quantum mechanical calculations of 153 organic molecules, including both pure aromatic molecules and molecules with mixed aromatic/olefinic/aliphatic hybridizations. We found that many of the C-H stretching vibrational modes in polycyclic aromatic hydrocarbon (PAH) molecules are coupled. Even considering the un-coupled modes only, the correlation between the band intensity ratios and the structure of the PAH molecule is not observed and the 3.28 and 3.30 micron features cannot be directly interpreted in the PAH model. Based on these results, the possible aromatic, olefinic and aliphatic origins of the 3.3 micron feature are discussed. We suggest that the 3.28 micron feature is assigned to aromatic C-H stretch whereas the 3.30 micron feature is olefinic. From the ratio of these two features, the relative olefinic to aromatic content of the carrier can be determined.-
dc.languageeng-
dc.publisherAmerican Astronomical Society, co-published with Institute of Physics Publishing, Inc. The Journal's web site is located at http://iopscience.iop.org/0004-637X/-
dc.relation.ispartofThe Astrophysical Journal-
dc.rightsThe Astrophysical Journal. Copyright © American Astronomical Society, co-published with Institute of Physics Publishing, Inc.-
dc.subjectISM: lines and bands-
dc.subjectISM: molecules-
dc.titleOn The Origin Of The 3.3 Micron Unidentified Infrared Emission Feature-
dc.typeArticle-
dc.identifier.emailSadjadi, S: abdi1374@connect.hku.hk-
dc.identifier.emailZhang, Y: zhangy96@hku.hk-
dc.identifier.emailKwok, S: deannote@hku.hk-
dc.identifier.authorityZhang, Y=rp00841-
dc.identifier.authorityKwok, S=rp00716-
dc.description.naturepostprint-
dc.identifier.doi10.3847/1538-4357/aa8141-
dc.identifier.scopuseid_2-s2.0-85028725305-
dc.identifier.hkuros273764-
dc.identifier.volume845-
dc.identifier.issue2-
dc.identifier.spage123:1-
dc.identifier.epage13-
dc.identifier.isiWOS:000408111400009-
dc.publisher.placeUnited States-
dc.identifier.issnl0004-637X-

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