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J/A+A/319/318 PAH hypothesis (Pauzat+ 1997)
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The PAH hypothesis: a computational experiment on the combined effects of
ionization and dehydrogenation on the IR signatures
Pauzat F., Talbi D., Ellinger Y.
<Astron. Astrophys. 319, 318 (1997)>
=1997A&A...319..318P (SIMBAD/NED BibCode)
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ADC_Keywords: Interstellar medium ; Spectra, infrared
Keywords: molecular data - molecular processes - ISM: molecules -
infrared: ISM: lines and bands
Abstract:
IR spectra of anthracene and pyrene derivatives, serving as models for
isolated, linear and isolated, compact PAHs, respectively, have been
calculated using ab-initio quantum mechanical methods. The separate
and combined effects of ionization and multiple dehydrogenation have
been studied. This study confirms and refines the trends of our
preliminary paper on the smallest possible PAH, naphthalene. If small
PAHs are responsible for any UIR bands, they should be ionized and
partially dehydrogenated, with a few triple bonds at the periphery of
the carbon skeleton.
In the appendix are given the complete IR spectra of all the isomers
of the derivatives of anthracene and pyrene calculated for the purpose
of this study. Tables I are for anthracene and Tables II for pyrene.
Positions of the the missing hydrogens in the dehydrogenated species
are referred as in Figures 1 and 2 of the original publication.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1a 33 66 Computed IR spectra of neutral anthracene
tablea1b 33 60 (1-2) doubly-dehydrogenated Anthracene IR spectra
tablea1c 33 60 (2-3) doubly-dehydrogenated Anthracene IR spectra
tablea1d 33 54 (1,2-3,4) quadri-dehydrogenated Anthracene IR spectra
tablea2a 33 72 Computed IR spectra of neutral Pyrene
tablea2b 33 66 (1-2) doubly-dehydrogenated Pyrene IR spectra
tablea2c 33 66 (4-5) doubly-dehydrogenated Pyrene IR spectra
tablea2d 33 60 (1,2-4,5) quadri-dehydrogenated Pyrene IR spectra
tablea2e 33 60 (1,2-7,8) quadri-dehydrogenated Pyrene IR spectra
tablea2f 33 60 (1,2-8,9) quadri-dehydrogenated Pyrene IR spectra
tablea2g 33 60 (1,2-11,12) quadri-dehydrogenated Pyrene IR spectra
tablea2h 33 60 (4,5-11,12) quadri-dehydrogenated Pyrene IR spectra
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Byte-by-byte Description of file: tablea*
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Bytes Format Units Label Explanations
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1- 3 A3 --- Sym. Symmetry representation of the vibration
5- 10 A6 --- Attrib. Assignment of the vibration (1)
12- 15 I4 cm-1 nuN Neutral wave number
17- 19 I3 km/mol IntN ? Neutral intensity
21- 24 I4 cm-1 nuC Cation wave number
26- 29 I4 km/mol IntC Cation intensity
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Note (1): r(CH) : CH bond stretching
R(CC) : CC bond stretching
a(CCC): CCC in-plane bending
b(CH) : CH in-plane bending
e(CH) : CH out-of-plane bending
t(CCC): out-of-plane ring deformation
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Acknowledgements: Yves Ellinger <ellinger@vega.ens.fr>
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(End) Patricia Bauer [CDS] 24-Feb-1997