Interstellar polycyclic aromatic hydrocarbons - The infrared emission bands, the excitation/emission mechanism, and the astrophysical implications
- NASA, Ames Research Center, Moffett Field, CA (USA) California Univ., Berkeley (USA) Michigan Univ., Ann Arbor (USA)
A comprehensive study of the PAH hypothesis is presented, including the interstellar, IR spectral features which have been attributed to emission from highly vibrationally excited PAHs. Spectroscopic and IR emission features are discussed in detail. A method for calculating the IR fluorescence spectrum from a vibrationally excited molecule is described. Analysis of interstellar spectrum suggests that the PAHs which dominate the IR spectra contain between 20 and 40 C atoms. The results are compared with results from a thermal approximation. It is found that, for high levels of vibrational excitation and emission from low-frequency modes, the two methods produce similar results. Also, consideration is given to the relationship between PAH molecules and amorphous C particles, the most likely interstellar PAH molecular structures, the spectroscopic structure produced by PAHs and PAH-related materials in the UV portion of the interstellar extinction curve, and the influence of PAH charge on the UV, visible, and IR regions. 229 refs.
- OSTI ID:
- 6966798
- Journal Information:
- Astrophysical Journal, Supplement Series; (USA), Vol. 71; ISSN 0067-0049
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
INTERSTELLAR SPACE
CHEMICAL COMPOSITION
POLYCYCLIC AROMATIC HYDROCARBONS
COSMOCHEMISTRY
DEUTERIUM
EMISSION SPECTRA
EXCITATION
INFRARED RADIATION
SPECTROSCOPY
AROMATICS
CHEMISTRY
ELECTROMAGNETIC RADIATION
ENERGY-LEVEL TRANSITIONS
HYDROCARBONS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
RADIATIONS
SPACE
SPECTRA
STABLE ISOTOPES
640105* - Astrophysics & Cosmology- Galaxies