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. =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 CH_3_^13^C(O)CH_3_ and ^13^CH_3_C(O)CH_3_ and search for them in Sagittarius B2(N2). We investigated the laboratory rotational spectrum of isotopically enriched CH_3_^13^C(O)CH_3_ between 40GHz and 910GHz and of acetone between 36GHz and 910GHz in order to study ^13^CH_3_C(O)CH_3_ 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 CH_3_^13^C(O)CH_3_ and 63 new transitions of ^13^CH_3_C(O)CH_3_ 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 {nu}_12_=1 and {nu}_17_=1 of CH_3_C(O)CH_3_ improve only marginally. No transition of CH_3_^13^C(O)CH_3_ is clearly detected toward the hot molecular core Sgr B2(N2). However, we report a tentative detection of ^13^CH_3_C(O)CH_3_ with a ^12^C/^13^C 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 CH_3_^13^C(O)CH_3_ and CH_3_C(O)CH_3_ are reliable into the terahertz region. The spectrum of ^13^CH_3_C(O)CH_3_ should be revisited in the laboratory with an enriched sample. The torsionally excited states v_12_=1 and v_17_=1 of CH_3_C(O)CH_3_ 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, CH_3_C(O)CH_3_, and CH_3_^13^C(O)CH_3_ are described by robust models, allowing for proper modeling of these species in astronomical sources. The predicted transition frequencies by our derived models for CH_3_^13^C(O)CH_3_ and CH_3_C(O)CH_3_ 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: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file a12c.dat 102 2259 Transitions included in the fit of the GS of acetone12C (CH_3_C(O)CH_3_) a2-13c.dat 102 9755 Transitions included in the fit of the GS of acetone-2-13C (CH_3_13C(O)CH_3_) a1-13c.dat 102 118 Transitions included in the fit of the GS of acetone-1-13C (^13^CH_3_C(O)CH_3_) a12cv121.dat 102 1660 Transitions included in the fit of v12=1 of acetone-12C (CH_3_C(O)CH_3_-v12=1) a12cv171.dat 102 1037 Transitions included in the fit of v17=1 of acetone-12C (CH_3_C(O)CH_3_-v17=1) -------------------------------------------------------------------------------- Byte-by-byte Description of file: a*.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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) -------------------------------------------------------------------------------- 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 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 -------------------------------------------------------------------------------- Acknowledgements: Oliver Zingsheim, zingsheim(at)ph1.uni-koeln.de ================================================================================ (End) Patricia Vannier [CDS] 20-Jun-2019