J/A+A/616/A173ivo://CDS.VizieR/J/A+A/616/A173doi:10.26093/cds/vizier.36160173CDSKolesnikova L.Alonso E.R.Tercero B.Cernicharo J.Alonso J.L.2018-09-10T08:08:55Z2018-09-07T09:51:09ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frinterstellar-mediumspectroscopyRelatively high abundances of methyl isocyanate (CH_3_NCO), a methyl derivative of isocyanic acid (HNCO), found in the Orion KL and Sgr B2 molecular clouds suggest that its ethyl derivative, ethyl isocyanate (CH_3_CH_2_NCO), may also be present. The aim of this work is to provide accurate experimental frequencies of ethyl isocyanate in its ground and excited vibrational states in the millimeter wave region to support searches for it in the interstellar medium. The rotational spectrum of ethyl isocyanate was recorded at room temperature from 80 to 340GHz using the millimeter wave spectrometer in Valladolid. Assigned rotational transitions were analyzed using the S-reduced semirigid-rotor Hamiltonian. More than 1100 distinct frequency lines were analyzed for the ground vibrational state of the cis conformer as well as for three vibrational satellites corresponding to successive excitation of the lowest-energy C-N torsional mode. Newly determined rotational and centrifugal distortion constants were used for searches of spectral features of ethyl isocyanate in Orion KL and Sgr B2 clouds. Upper limits to CH_3_CH_2_NCO in these high-mass star-forming regions were obtained.2018A&A...616A.173Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/616/A173CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/610/A44 : Ethyl isocyanide submillimeter wave spectroscopyhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/616/A173https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/616/A173http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/616/A173https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/616/A173https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/616/A173http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/616/A173GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/616/A173/table4Fitted rotational transitions of ethyl isocyanate in the ground state and excited vibrational statesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ1Upper state J quantum numberphys.atmol.configurationintKa1Upper state Ka quantum numberphys.atmol.qnintKc1Upper state Kc quantum numberphys.atmol.qnintJ0Lower state J quantum numberphys.atmol.configurationintKa0Lower state Ka quantum numberphys.atmol.qnintKc0Lower state Kc quantum numberphys.atmol.qnintFreqobsObserved transition frequencyMHzem.freqdoubleO-CObserved minus calculated frequencyMHzstat.fit.residualfloatUncExperimental uncertaintyMHzstat.errorfloat(O-C)b? Observed minus calculated frequency for blendsMHzem.freq;stat.fit.omcfloatnullablewb? Weight of the components of the blendsstat.weight;phys.atmol.weightfloatnullableNotesNotesmeta.notecharJ/A+A/616/A173/table5Perturbed rotational transitions of ethyl isocyanate in the ground vibrational state measured by the graphical Loomis-Wood type plot techniquerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ1Upper state J quantum numberphys.atmol.configurationintKa1Upper state Ka quantum numberphys.atmol.qnintKc1Upper state Kc quantum numberphys.atmol.qnintJ0Lower state J quantum numberphys.atmol.configurationintKa0Lower state Ka quantum numberphys.atmol.qnintKc0Lower state Kc quantum numberphys.atmol.qnintFreqobsObserved transition frequencyMHzem.freqdoubleUncExperimental uncertaintyMHzstat.errorfloat