The interstellar chemistry of PAH cations
Article Abstract:
Diffuse interstellar bands (DIBs) are widely believed to arise from gas-phase organic molecules in the interstellar medium. Many emission features in astronomical infrared spectra could arise from polycyclic aromatic hydrocarbons (PAHs) which may also be abundant in the interstellar medium. It has been suggested that ionized PAHs could be the source of the DIBs, and laboratory experiments have shown that small, positively charged PAHs have similar absorption features to DIBs. A further study found that PAH cations are very reactive and it is suggested that protonated PAH cations should be the focus of future links between molecular absorption features and the DIBs.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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Do two photons make a band?
Article Abstract:
A proposed model identifies molecular hydrogen (H2) as a potential diffuse interstellar band (DIB) carrier. A two-photon process, occurring in regions of intense fields of ultraviolet radiation, maintains many excited H2 molecules that produce the DIBs by absorbing visible-wavelength photons. However, real DIBs fail to correlate with the environments proposed in the model. Intensive searches reveal only small quantities of H2 molecules and the wavelength coincidences used lie beyond observational uncertainties.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Molecular nitrogen in space
Article Abstract:
David C. Knauth and colleagues claim the first detection of molecular nitrogen (N2) in interstellar space. One of the difficulties in detecting interstellar N(sub 2) arises from the fact that the symmetric diatomic molecules gas no allowed rotational or vibrational transitions.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2004
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