J/A+A/663/A132 1-propanimine measured freq. and residuals (Margules+, 2022)
Submillimeter wave spectroscopy and astronomical search for 1-propanimine.
Margules L., Remijan A., Belloche A., Motiyenko R.A., McGuire B.A., Xue C.,
Muller H.S.P., Garrod R.T., Menten K.M., Guillemin J.C.
<Astron. Astrophys. 663, A132 (2022)>
=2022A&A...663A.132M 2022A&A...663A.132M (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Radio lines ;
Spectroscopy
Keywords: ISM: molecules - methods: laboratory: molecular - submillimeter: ISM -
molecular data - astrochemistry - line: identification
Abstract:
Methanimine, CH2NH, and ethanimine, CH3CHNH, were both detected in
the interstellar medium (ISM), the former in the 1970s and the latter
nearly a decade ago. By analogy with nitriles, for which hydrogen
cyanide, acetonitrile, and ethyl cyanide are the most abundant,
n-propanimine was suggested as a candidate for detection in the ISM.
To date, no measurements of the rotational spectrum of 1-propanimine
have been made. We present measurements and an analysis of its
spectrum in the millimeter- and submillimeter-wave domain in order to
provide an accurate prediction that is required to search for this
molecule in the ISM.
The rotational spectrum of propanimine was investigated from 150 to
470GHz. Watson's asymmetric top Hamiltonian in the Ir
representation and S reduction was used for the analysis. The new
prediction allowed us to search for 1-propanimine toward the high-mass
star forming region Sagittarius B2(N), the dark molecular cloud TMC-1,
as well as a sample of low-mass protostellar objects. These sources
were observed with the Atacama Large Millimeter/submillimeter Array,
the Green Bank Telescope, or the IRAM 30m telescope.
A total of 585 and 296 transitions of the E and Z-1-propanimine,
respectively, were newly assigned and fitted in the laboratory spectra
recorded up to 470GHz. Quantum numbers up to J=73 and Ka=18 were
reached for the E isomer and J=56 and Ka=17 for the Z isomer. We
report the nondetection of 1-propanimine toward all astronomical
sources investigated in this work. We find in particular that
1-propanimine is at least 20 times less abundant than methanimine in
the envelope of the high-mass star forming region Sagittarius B2(N).
The accurate spectroscopic prediction of its spectrum provided in this
work will allow astronomers to continue the search for 1-propanimine
in the ISM.
Description:
Millimeter and submillimeter wave spectra of the E and Z stereoisomers
of propanimine were assigned up to 470GHz. This has permitted us to
produce accurate predictions of the spectra of both isomers and made
possible a search for this molecule in the ISM.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
s1.dat 76 1276 Measured frequencies of the E-propanimine and
residuals from the fit (table 2)
s2.dat 76 454 Measured frequencies of the Z-propanimine and
residuals from the fit (table 3)
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Byte-by-byte Description of file: s1.dat s2.dat
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Bytes Format Units Label Explanations
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2- 5 I4 --- Nr Line number
6 A1 --- --- [:]
9- 10 I2 --- J" Upper J quantum number
12- 13 I2 --- Ka" Upper Ka quantum number
15- 16 I2 --- Kc" Upper Kc quantum number
18- 19 I2 --- J' Lower J quantum number
21- 22 I2 --- Ka' Lower Ka quantum number
24- 25 I2 --- Kc' Lower Kc quantum number
46- 56 F11.4 MHz Freq Observed transition frequency
60- 66 F7.4 MHz O-C Observed - Calculated frequencies
71- 76 F6.4 MHz unc Experimental uncertainty
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Acknowledgements:
Laurent Margules, laurent.margules(at)univ-lille.fr
(End) Laurent Margules [Phlam, France], Patricia Vannier [CDS] 27-May-2022