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标题：Rotational rest frequencies of the low lying vibrational states of n-propyl cyanide from extensive laboratory measurements up to 506 GHz ⋆
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作者：Delong Liu ; Adam Walters ; Nadine Wehres 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：622
DOI：10.1051/0004-6361/201834227
语种：English
出版社：EDP Sciences
摘要：Context.The spectra of four low-lying vibrational states of bothantiandgaucheconformers ofnormal-propyl cyanide were previously measured and analyzed in two spectral windows between 36 and 127 GHz. All states were then identified in a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1.Aims.We wanted to extend the measurements and analysis up to 506 GHz to provide accurate predictions over a much wider range of frequencies, quantum numbers and energies.Methods.We carried out measurements in two additional frequency windows up to 506 GHz.Results.For thegaucheconformer, a large number of botha- andb-type transitions were identified. For theanticonformer, transitions were predominantly, but not exclusively,a-type. We hence improved molecular parameters for the ground states of bothanti- andgauche-n-propyl cyanide and for excited vibrational states of thegaucheconformer (v30 = 1,v29 = 1,v30 = 2,v28 = 1) andanticonformer (v30 = 1,v18 = 1,v30 = 2,v29 = 1) with high order coupling parameters determined betweenv18 = 1 andv30 = 2. Parameters are published for the first time forv18 = v30 = 1 of theanticonformer and forv29 = v30 = 1 of thegaucheconformer.Conclusions.In total 15385 lines have been incorporated in the fits and should allow good predictions for unperturbed lines over the whole operating range of radio-telescopes. Evidence is found for vibrational coupling for some levels above 380 GHz. The coupling betweenv18 = 1 andv30 = 2 of theanticonformer has been well characterized. An additional list of 740 lines showing potential but as yet unidentified coupling has been provided for astrophysical identification.
关键词：enmolecular dataline: identificationastrochemistrymethods: laboratory: molecularISM: moleculessubmillimeter: ISM