Science, Vol 265, Issue 5179, 1686-1689
Copyright © 1994 by American Association for the Advancement of Science
The unidentified interstellar infrared bands: PAHs as carriers?
S Schlemmer,
DJ Cook,
JA Harrison,
B Wurfel,
W Chapman,
and
RJ Saykally
Department of Chemistry, University of California, Berkeley 94720-1460, USA.
Infrared emission spectra of gas-phase naphthalene and pyrene have been measured in the range of 3 to 7.5 micrometers with ultraviolet laser desorption-excitation and a spectroscopic technique featuring single-photon counting in the infrared. The spectra were compared with the unidentified infrared emission bands that are observed in many astronomical objects. Marked discrepancies between those observations and the laboratory emission spectra in the wavelengths and relative intensities of principal spectral features led to the conclusion that small neutral unsubstituted polycyclic aromatic hydrocarbons cannot be the carriers of the unidentified infrared emission bands.
