J/A+A/629/A72 Isotopic acetone laboratory rotational spectroscopy (Ordu+, 2019)
Laboratory rotational spectroscopy of isotopic acetone, CH3 13C(O)CH3 and
13CH3C(O)CH3, and astronomical search in Sagittarius B2(N2).
Ordu M.H., Zingsheim O., Belloche A., Lewen F., Garrod R.T., Menten K.M.,
Schlemmer S., Mueller H.S.P.
<Astron. Astrophys. 629, A72 (2019)>
=2019A&A...629A..72O 2019A&A...629A..72O (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: molecular data - methods: laboratory: molecular -
techniques: spectroscopic - radio lines: ISM - ISM: molecules -
ISM: individual objects: Sagittarius B2(N)
Abstract:
Spectra of minor isotopic species of molecules that are abundant in
space may also be detectable. Their respective isotopic ratios may
provide clues about the formation of these molecules. Emission lines
of acetone in the hot molecular core Sagittarius B2(N2) are strong
enough to warrant a search for its singly substituted 13C isotopologs.
We want to study the rotational spectra of CH313C(O)CH3 and
13CH3C(O)CH3 and search for them in Sagittarius B2(N2).
We investigated the laboratory rotational spectrum of isotopically
enriched CH313C(O)CH3 between 40GHz and 910GHz and of acetone
between 36GHz and 910GHz in order to study 13CH3C(O)CH3 in
natural isotopic composition. In addition, we searched for emission
lines produced by these species in a molecular line survey of
Sagittarius B2(N) carried out with the Atacama Large
Millimeter/submillimeter Array (ALMA). Discrepancies between
predictions of the main isotopic species and the ALMA spectrum
prompted us to revisit the rotational spectrum of this isotopolog.
We assigned 9711 new transitions of CH313C(O)CH3 and 63 new
transitions of 13CH3C(O)CH3 in the laboratory spectra. More than
1000 additional lines were assigned for the main isotopic species.We
modeled the ground state data of all three isotopologs satisfactorily
with the ERHAM program. We find that models of the torsionally excited
states ν12=1 and ν17=1 of CH3C(O)CH3 improve only
marginally. No transition of CH313C(O)CH3 is clearly detected
toward the hot molecular core Sgr B2(N2). However, we report a
tentative detection of 13CH3C(O)CH3 with a 12C/13C isotopic
ratio of 27 that is consistent with the ratio previously measured for
alcohols in this source. Several dozens of transitions of both
torsional states of the main isotopolog are detected as well.
Our predictions of CH313C(O)CH3 and CH3C(O)CH3 are reliable
into the terahertz region. The spectrum of 13CH3C(O)CH3 should
be revisited in the laboratory with an enriched sample. The
torsionally excited states v12=1 and v17=1 of CH3C(O)CH3
were not reproduced satisfactorily in our models. Nevertheless,
transitions pertaining to both states could be identified
unambiguously in Sagittarius B2(N2).
Description:
The main isotopic species of acetone, CH3C(O)CH3, and
CH313C(O)CH3 are described by robust models, allowing for proper
modeling of these species in astronomical sources. The predicted
transition frequencies by our derived models for CH313C(O)CH3
and CH3C(O)CH3 are reliable into the terahertz region. Therefore,
these models can be of high interest for the analyses of hot-core and
hot-corino surveys performed with ALMA in all its bands.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
a12c.dat 102 2259 Transitions included in the fit of the GS of
acetone12C (CH3C(O)CH3)
a2-13c.dat 102 9755 Transitions included in the fit of the GS of
acetone-2-13C (CH313C(O)CH3)
a1-13c.dat 102 118 Transitions included in the fit of the GS of
acetone-1-13C (13CH3C(O)CH3)
a12cv121.dat 102 1660 Transitions included in the fit of v12=1 of
acetone-12C (CH3C(O)CH3-v12=1)
a12cv171.dat 102 1037 Transitions included in the fit of v17=1 of
acetone-12C (CH3C(O)CH3-v17=1)
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Byte-by-byte Description of file: a*.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Sigma1 First symmetry label of upper and lower state
4- 6 I3 --- Sigma2 Second symmetry label of upper and lower state
7- 9 I3 --- J' Upper state J quantum number
10- 12 I3 --- Ka' Upper state Ka quantum number
13- 15 I3 --- Kc' Upper state Kc quantum number
16- 18 I3 --- J" Lower state J quantum number
19- 21 I3 --- Ka" Lower state Ka quantum number
22- 24 I3 --- Kc" Lower state Kc quantum number
28- 38 F11.4 MHz Freq Observed transition frequency in MHz
42- 47 F6.4 MHz Unc Experimental uncertainty in MHz
51- 57 F7.4 MHz (O-C) Observed minus calculated frequency in MHz
61- 64 F4.2 --- w ? Weight of the component in group of lines
67- 74 F8.4 --- Dev ? Deviation ratio in (O-C)/Unc
78- 84 F7.4 --- wDev ? Averaged weighted deviation ratio in group
of lines
88-102 A15 --- Notes Source of data (reference) (1)
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Note (1): References as follows:
Peter1965 = Peter, R., and Dreizler, H., Z. Naturforsch. 301 (1965) 20a
Oldag1992 = Oldag, F., and Sutter, D. H., Z. Naturforsch. 47a (1992) 527
White1975 = White, W. F., NASA Tech. Note D-7904 (1975) 121
Groner2002 = Groner P., et al., Astrophysic. J. Suppl. S. 142 (2002) 145,
2002ApJS..142..145G 2002ApJS..142..145G
Vacherand1986 = Vacherand, J. M., et al., J. Mol. Spectrosc. 118 (1986) 355
Groner2006 = Groner P., et al., J. Mol. Spectrosc. 795 (2006) 173
Groner2008 = Groner P., et al., J. Mol. Spectrosc. 251 (2008) 180
Lovas2006 = Lovas, F.J. and Groner, P., J. Mol. Spectrosc. 236 (2006) 173
ThisWork = Newly measured and assigened transitions of this work
* = Newly assigned transitions of this work
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Acknowledgements:
Oliver Zingsheim, zingsheim(at)ph1.uni-koeln.de
(End) Patricia Vannier [CDS] 20-Jun-2019