The ir emission features: Emission from PAH (Polycyclic Aromatic Hydrocarbons) molecules and amorphous carbon particles

Conference · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6581763

Allamandola, L J; Tielens, A G.G.M.; Barker, J R

PAHs can have several forms in the interstellar medium. To assess the importance of each requires the availability of a collection of high quality, complete mid-ir interstellar emission spectra, a collection of laboratory spectra of PAH samples prepared under realistic conditions and a firm understanding of the microscopic emission mechanism. Given what we currently know about PAHs, the spectroscopic data suggests that there are at least two components which contribute to the interstellar emission spectrum: free molecule sized PAHs producing the narrow features and amorphous carbon particles (which are primarily made up of an irregular ''lattice'' of PAHs) contributing to the broad underlying components. An exact treatment of the ir fluorescence from highly vibrationally excited large molecules shows that species containing between 20 and 30 carbon atoms are responsible for the narrow features, although the spectra match more closely with the spectra of amorphous carbon particles. Since little is known about the spectroscopic properties of free PAHs and PAH clusters, much laboratory work is called for in conjunction with an observational program which focuses on the spatial characteristics of the spectra. In this way the distribution and evolution of carbon from molecule to particle can be traced. 38 refs., 9 figs.

• Research Organization: National Aeronautics and Space Administration, Moffett Field, CA (USA). Ames Research Center; Michigan Univ., Ann Arbor (USA). Dept. of Atmospheric and Oceanic Science
• DOE Contract Number: FG02-85ER13442
• OSTI ID: 6581763
• Report Number(s): CONF-8602110-1; ON: DE87003377
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AROMATICS
COSMIC GASES
DATA
EMISSION SPECTRA
EXPERIMENTAL DATA
FLUIDS
GASES
HYDROCARBONS
INFORMATION
INFRARED SPECTRA
INTERSTELLAR SPACE
NUMERICAL DATA
ORGANIC COMPOUNDS
POLYCYCLIC AROMATIC HYDROCARBONS
SPACE
SPECTRA