Infrared emission spectra of candidate interstellar aromatic molecules
Article Abstract:
Neutral polycyclic aromatic hydrocarbons (PAH) of small size may contribute to less than 10% of the emissions in the unidentified infrared bands (UIR) of intersellar sources. In the laboratory, ultraviolet-laser-induced desorption was used to incorporate excited gas phase PAHs in a low-infrared-background cryogenic vacuum chamber. Bands with substantial differences appearing in typical spectral regions combine to generate an apparent continuum in the UIR spectra between 5.5 and 9.5 micrometers. The 3.3 micrometer bands present in the spectra exhibit considerable invariance in frequency among the various PAHs.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Characterization of a cage form of the water hexamer
Article Abstract:
Terahertz laser vibration-rotation tunnelling spectra reveals that the stable form of (H2O)6 has a cage-like structure supported by eight hydrogen bonds. The high intermolecular zero-point energies of the hydrogen bonds are important for the low energy structure. Calculations based on the diffusion quantum Monte Carlo technique indicate that the O-O bond has an average distance of 2.85 Angstroms for the cage hexamer and 2.76 Angstroms for the cyclic isomer. The values compare well with that of liquid water at 298 degrees Kelvin and ice at 223 degrees Kelvin respectively.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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An enhanced cosmic-ray flux towards Persei inferred from a laboratory study of the H3+--e- recombination rate
Article Abstract:
Study of diffuse interstellar clouds in which the molecular ion H3+ is plentiful has resulted in the discovery that the ionization rate within the clouds is 40 times faster than previously known. If this ionization rate is found to be standard in diffuse clouds, it will allow one of the basic conflicts in interstellar chemistry to be resolved.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2003
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