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FT-IR spectroscopic studies of polycyclic aromatic hydrocarbonsProper assessment of the hypothesis which correlates polycyclic aromatic hydrocarbons (PAHs) with the unidentified infrared emission bands requires additional experimental laboratory data. In order to address this need, thermal infrared emission studies were performed on a subset of PAHs suggested to be of astrophysical importance. It was proposed that infrared emission from interstellar PAHs occurs following absorption of an ultraviolet photon. Since energy transfer to the ground electronic state can be rapid for a species in which intersystem crossing is negligible, the emission spectrum may be viewed as resulting from an equilibrium vibrational temperature (Leger and d'Hendecourt, 1987). This has been the basis for using infrared absorption spectra to calculate the corresponding emission spectra at various temperatures. These calculations were made using room temperature infrared absorption coefficients instead of those at the temperature of interest because of the latter's unavailability. The present studies are designed to address the differences between the calculated and experimental thermal emission spectra and to provide information which will be useful in future ultraviolet induced infrared fluorescence studies. The emission spectra have been obtained for temperatures up to 825K using an emission cell designed to mount against an external port of an FT-IR spectrometer. These spectra provide information concerning relative band intensities and peak positions which is unavailable from previous calculations.
Document ID
19900018276
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Salisbury, D. W.
(Maryland Univ. College Park., United States)
Allen, J. E., Jr.
(NASA Goddard Space Flight Center Greenbelt, MD., United States)
Donn, B.
(NASA Goddard Space Flight Center Greenbelt, MD., United States)
Moore, W. J.
(Naval Research Lab. Washington, DC., United States)
Khanna, R. K.
(Naval Research Lab. Washington, DC., United States)
Date Acquired
September 6, 2013
Publication Date
April 1, 1990
Publication Information
Publication: NASA, Ames Research Center, Carbon in the Galaxy: Studies from Earth and Space
Subject Category
Inorganic And Physical Chemistry
Accession Number
90N27592
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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