Ionized polycyclic aromatic hydrocarbons and the diffuse interstellar bands

Journal Article · Sat Jun 01 04:00:00 EDT 1985 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/184488· OSTI ID:5374253

Crawford, M K; Tielens, A G.G.M.; Allamandola, L J

A good case has recently been made that the unidentified infrared emission features arise from positively charged, partially hydrogenated polycyclic aromatic hydrocarbons (PAHs). In the Letter, we suggest that these exceedingly stable ions are also the carriers of the diffuse interstellar bands. Although a large variety of PAH isomers is possible, the more condensed forms are substantially more stable than the less condensed forms and are expected to be dominant in harsh interstellar environment. While neutral PAHs do not absorb in the visible, their ionized counterparts do. Because of their low ionization potential, a substantial fraction of the interstellar PAHs will be ionized. Visible spectra of the most stable PAH cations isolated in glasses are compared directly to the interstellar band spectra. Although the laboratory spectra are on an extremely compressed scale and solid state shifts are present, the comparison is favorable. Since little information is available concerning the spectroscopic properties of these species in the gas phase, a considerable amount of laboratory and theoretical work is called for to test this hypothesis.

• Research Organization: Physics Department, University of California, Berkeley
• OSTI ID: 5374253
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 293:1; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION SPECTRA
AROMATICS
CHARGED PARTICLES
CONDENSED AROMATICS
HYDROCARBONS
INFRARED SPECTRA
INTERSTELLAR GRAINS
IONS
ORGANIC COMPOUNDS
PARTICLES
POLYCYCLIC AROMATIC HYDROCARBONS
SPECTRA
VISIBLE SPECTRA