J/A+A/636/A33 Glutaronitrile rotational spectroscopy (Cabezas+, 2020)
Rotational spectroscopy and astronomical search of glutaronitrile.
Cabezas C., Bermudez C., Endo Y., Tercero B., Cernicharo J.
<Astron. Astrophys. 636, A33 (2020)>
=2020A&A...636A..33C 2020A&A...636A..33C (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: ISM: molecules - methods: laboratory: molecular -
molecular data - line: identification
Abstract:
Nitriles constitute almost 15% of the molecules observed in the
interstellar medium (ISM), surprisingly only two dinitriles have been
detected in the ISM so far. The lack of astronomical detections for
dinitriles may be partly explained by the absence of laboratory
rotational spectroscopic data. Our goal is the investigation of the
rotational spectrum of glutaronitrile, NC-CH2-CH2-CH2-CN, in
order to allow its possible detection in the ISM. The rotational
spectra of glutaronitrile was measured using two different
experimental setups. A Fourier transform microwave spectrometer was
employed to observe the supersonic jet rotational spectrum of
glutaronitrile between 6 and 20GHz. In addition the mmW spectrum was
observed in the frequency range 72-116.5GHz using a broadband
millimeter-wave spectrometer based on radio astronomy receivers with
fast Fourier transform backends. The spectral searches were supported
by high-level ab initio calculations. A total of 111 rotational
transitions with maximum values of J and Ka quantum numbers 54 and 18,
respectively, were measured for the gg conformer of glutaronitrile.
The analysis allowed us to accurately determine the rotational,
nuclear quadrupole coupling, quartic and sextic centrifugal distortion
constants. These rotational parameters were employed to search for
glutaronitrile in the cold and warm molecular clouds Orion KL, Sgr
B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30m
at 3mm. Glutaronitrile was not detected and the upper limits column
densities are derived. Those are a factor of 1.5 and 5 lower than
those obtained for the total column densities of the analogous
succionitrile in Orion KL and Sgr B2, respectively.
Description:
The rotational investigation of a larger dinitrile, glutaronitrile,
with one more atomic carbon in the hydrocarbon skeleton than
succinonitrile is reported. To record the rotational spectrum of
glutaronitrile, two different spectroscopic techniques have been
employed; a high resolution Fourier transform microwave (FTMW) pulsed
supersonic jet spectrometer operating in the centimetre wave region
and a broadband millimetre-wave spectrometer based on radio astronomy
receivers with fast Fourier transform backends.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 62 228 Measured rotational transitions for
glutaronitrile observed by FTMW spectroscopy
tablea2.dat 65 89 Measured rotational transitions for
glutaronitrile observed in the mmW region
tablea3.dat 47 16239 Predicted transition frequencies for
glutaronitrile up to 300GHz
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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2 I1 --- J' Quantum number J for upper level
5 I1 --- Ka' Quantum number Ka for upper level
8 I1 --- Kc' Quantum number Kc for upper level
11 I1 --- I' Quantum number I for upper level
14 I1 --- F' Quantum number F for upper level
17 I1 --- J" Quantum number J for lower level
20 I1 --- Ka" Quantum number Ka for lower level
23 I1 --- Kc" Quantum number Kc for lower level
26 I1 --- I" Quantum number I for lower level
29 I1 --- F" Quantum number F for lower level
35- 43 F9.3 MHz Freq Measured frequency
48- 53 F6.3 MHz O-C Difference between observed & calculated freq.
58- 62 F5.3 MHz Uncert Uncertainty associated to frequency
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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3- 4 I2 --- J' Quantum number J for upper level
7- 8 I2 --- Ka' Quantum number Ka for upper level
11- 12 I2 --- Kc' Quantum number Kc for upper level
17- 18 I2 --- J" Quantum number J for lower level
21- 22 I2 --- Ka" Quantum number Ka for lower level
25- 26 I2 --- Kc" Quantum number Kc for lower level
31- 41 F11.4 MHz Freq Measured frequency
47- 52 F6.3 MHz O-C Difference between observed & calculated freq.
61- 65 F5.3 MHz Uncert Uncertainty associated to frequency
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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2- 3 I2 --- J' Quantum number J for upper level
6- 7 I2 --- Ka' Quantum number Ka for upper level
10- 11 I2 --- Kc' Quantum number Kc for upper level
14- 15 I2 --- J" Quantum number J for lower level
18- 19 I2 --- Ka" Quantum number Ka for lower level
22- 23 I2 --- Kc" Quantum number Kc for lower level
27- 37 F11.4 MHz Freq Frequency
41- 47 F7.4 [nm2/MHz] logInt Base 10 logarithm of the integrated intensity
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Acknowledgements:
Carlos Cabezas, carlos.cabezas(at)csic.es
(End) Patricia Vannier [CDS] 04-Mar-2020