Details
| Original language | English |
|---|---|
| Pages (from-to) | 8970-8976 |
| Number of pages | 7 |
| Journal | Physical Chemistry Chemical Physics |
| Volume | 19 |
| Issue number | 13 |
| Early online date | 16 Mar 2017 |
| Publication status | Published - 7 Apr 2017 |
Abstract
The simplest tricyclic aromatic nitrogen heterocyclic molecules 5,6-benzoquinoline and 7,8-benzoquinoline are possible candidates for detection of aromatic systems in the interstellar medium. Therefore the pure rotational spectra have been recorded using frequency-scanned Stark modulated, jet-cooled millimetre wave absorption spectroscopy (48-87 GHz) and Fourier Transform Microwave (FT-MW) spectroscopy (2-26 GHz) of a supersonic rotationally cold molecular jet. Guided by theoretical molecular orbital predictions, spectral analysis of mm-wave spectra, and higher resolution FT-MW spectroscopy provided accurate rotational and centrifugal distortion constants together with 14N nuclear quadrupole coupling constants for both species. The tricyclic frames of these species undergo low energy out-of-plane zero-point vibrations resulting in deviations from the moments of inertia that the rigid structure would exhibit. The determined inertial defects, along with those of similar species are used to develop an empirical formula for calculation of inertial defects of aromatic ring systems. The predictive ability of the formula is shown to be excellent in general for planar species with a number of pronounced out-of-plane vibrations. The resultant constants for the benzoquinolines are of sufficient accuracy to be used in astrophysical searches for planar aromatic heterocycles.
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In: Physical Chemistry Chemical Physics, Vol. 19, No. 13, 07.04.2017, p. 8970-8976.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - The radio spectra of planar aromatic heterocycles
T2 - How to quantify and predict the negative inertial defects
AU - Jahn, Michaela K.
AU - Grabow, Jens Uwe
AU - Travers, Michael J.
AU - Wachsmuth, Dennis
AU - Godfrey, Peter D.
AU - McNaughton, Don
N1 - Funding Information: We gratefully acknowledge support from Australian Research Council (D. McN.) and the Deutsche Forschungsgemeinschaft, the Deutsche Akademische Austauschdienst, as well as the Land Niedersachsen (J.-U. G). D. McN. also thanks the Royal Society of Chemistry for their generous travel support. D. W. thanks the Fonds der Chemischen Industrie for a FCI scholarship. The results presented here were partially carried out on the cluster system at the Leibniz University of Hannover, Germany. Publisher Copyright: © the Owner Societies. Copyright: Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/4/7
Y1 - 2017/4/7
N2 - The simplest tricyclic aromatic nitrogen heterocyclic molecules 5,6-benzoquinoline and 7,8-benzoquinoline are possible candidates for detection of aromatic systems in the interstellar medium. Therefore the pure rotational spectra have been recorded using frequency-scanned Stark modulated, jet-cooled millimetre wave absorption spectroscopy (48-87 GHz) and Fourier Transform Microwave (FT-MW) spectroscopy (2-26 GHz) of a supersonic rotationally cold molecular jet. Guided by theoretical molecular orbital predictions, spectral analysis of mm-wave spectra, and higher resolution FT-MW spectroscopy provided accurate rotational and centrifugal distortion constants together with 14N nuclear quadrupole coupling constants for both species. The tricyclic frames of these species undergo low energy out-of-plane zero-point vibrations resulting in deviations from the moments of inertia that the rigid structure would exhibit. The determined inertial defects, along with those of similar species are used to develop an empirical formula for calculation of inertial defects of aromatic ring systems. The predictive ability of the formula is shown to be excellent in general for planar species with a number of pronounced out-of-plane vibrations. The resultant constants for the benzoquinolines are of sufficient accuracy to be used in astrophysical searches for planar aromatic heterocycles.
AB - The simplest tricyclic aromatic nitrogen heterocyclic molecules 5,6-benzoquinoline and 7,8-benzoquinoline are possible candidates for detection of aromatic systems in the interstellar medium. Therefore the pure rotational spectra have been recorded using frequency-scanned Stark modulated, jet-cooled millimetre wave absorption spectroscopy (48-87 GHz) and Fourier Transform Microwave (FT-MW) spectroscopy (2-26 GHz) of a supersonic rotationally cold molecular jet. Guided by theoretical molecular orbital predictions, spectral analysis of mm-wave spectra, and higher resolution FT-MW spectroscopy provided accurate rotational and centrifugal distortion constants together with 14N nuclear quadrupole coupling constants for both species. The tricyclic frames of these species undergo low energy out-of-plane zero-point vibrations resulting in deviations from the moments of inertia that the rigid structure would exhibit. The determined inertial defects, along with those of similar species are used to develop an empirical formula for calculation of inertial defects of aromatic ring systems. The predictive ability of the formula is shown to be excellent in general for planar species with a number of pronounced out-of-plane vibrations. The resultant constants for the benzoquinolines are of sufficient accuracy to be used in astrophysical searches for planar aromatic heterocycles.
UR - http://www.scopus.com/inward/record.url?scp=85019848166&partnerID=8YFLogxK
U2 - 10.1039/c6cp07487a
DO - 10.1039/c6cp07487a
M3 - Article
C2 - 28300236
AN - SCOPUS:85019848166
VL - 19
SP - 8970
EP - 8976
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
SN - 1463-9076
IS - 13
ER -