PROTONATED POLYCYCLIC AROMATIC HYDROCARBONS REVISITED

Journal Article · Tue Feb 01 04:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/727/2/128· OSTI ID:21567508

Ricca, Alessandra ^[1]; Bauschlicher, Jr, Charles W ^[2]

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1. Carl Sagan Center, SETI Institute, 189 N. Bernardo Ave., Suite 100, Mountain View, CA 94043 (United States)
2. Entry Systems and Technology Division, Mail Stop 230-3, NASA Ames Research Center, Moffett Field, CA 94035 (United States)

We reconsider the contribution that singly protonated polycyclic aromatic hydrocarbons (PAHs; HPAH{sup +}s) might make to the Class A component of the 6.2 {mu}m interstellar emission feature in light of the recent experimental measurements of protonated naphthalene and coronene. Our calculations on the small HPAH{sup +}s have a band near 6.2 {mu}m, as found in experiment. While the larger HPAH{sup +}s still have emission near 6.2 {mu}m, the much larger intensity of the band near 6.3 {mu}m overwhelms the weaker band at 6.2 {mu}m, so that the 6.2 {mu}m band is barely visible. Since the large PAHs are more representative of those in the interstellar medium, our work suggests that large HPAH{sup +}s cannot be major contributors to the observed emission at 6.2 {mu}m (i.e., Class A species). Saturating large PAH cations with hydrogen atoms retains the 6.2 {mu}m Class A band position, but the rest of the spectrum is inconsistent with observed spectra.

• OSTI ID: 21567508
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 727; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AROMATICS
CONDENSED AROMATICS
EMISSION
HYDROCARBONS
INTERSTELLAR SPACE
NAPHTHALENE
ORGANIC COMPOUNDS
POLYCYCLIC AROMATIC HYDROCARBONS
SPACE