Universität zu Köln

Mueller, Holger S. P., Walters, Adam, Wehres, Nadine ORCID: 0000-0001-8881-2916, Belloche, Arnaud, Wilkins, Olivia H., Liu, Delong, Vicente, Remi, Garrod, Robin T., Menten, Karl M., Lewen, Frank and Schlemmer, Stephan ORCID: 0000-0002-1421-7281 (2016). Laboratory spectroscopic study and astronomical detection of vibrationally excited n-propyl cyanide. Astron. Astrophys., 595. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. We performed 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. We determined line intensities of n-propyl cyanide in the ground vibrational states of its gauche and anti conformers toward the hot molecular core Sagittarius B2(N2) which suggest that we should also be able to detect transitions pertaining to excited vibrational states. Aims. We wanted to determine spectroscopic parameters of low-lying vibrational states of both conformers of n-propyl cyanide to search for them in our ALMA data. Methods. We recorded laboratory rotational spectra of n-propyl cyanide in two spectral windows between 36 and 127 GHz. We searched for emission lines produced by these states in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the ground vibrational states assuming local thermodynamic equilibrium (LTE). Results. We have made extensive assignments of a-and b-type transitions of the four lowest vibrational states of the gauche conformer which reach J and K-a quantum numbers of 65 and 20, respectively. We assigned mostly a-type transitions for the anti conformer with J and K-a quantum numbers up to 48 and 24, respectively. Rotational and Fermi perturbations between two anti states allowed us to determine their energy difference. The resulting spectroscopic parameters enabled us to identify transitions of all four vibrational states of each conformer in our ALMA data. The emission features of all states, including the ground vibrational state, are well-reproduced with the same LTE modeling parameters, which gives us confidence in the reliability of the identifications, even for the states with only one clearly detected line. Conclusions. Emission features pertaining to the highest excited vibrational states of n-propyl cyanide reported in this work have been identified just barely in our present ALMA data. Features of even higher excited vibrational states may become observable in future, more sensitive ALMA spectra to the extent that the confusion limit will not have been reached. The C-13 isotopomers of this molecule are expected to be near the noise floor of our present ALMA data. We estimate that transitions of vibrationally excited iso-propyl cyanide or aminoacetonitrile, for example, are near the noise floor of our current data as well.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mueller, Holger S. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Walters, Adam UNSPECIFIED UNSPECIFIED UNSPECIFIED Wehres, Nadine UNSPECIFIED orcid.org/0000-0001-8881-2916 UNSPECIFIED Belloche, Arnaud UNSPECIFIED UNSPECIFIED UNSPECIFIED Wilkins, Olivia H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Liu, Delong UNSPECIFIED UNSPECIFIED UNSPECIFIED Vicente, Remi UNSPECIFIED UNSPECIFIED UNSPECIFIED Garrod, Robin T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Menten, Karl M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lewen, Frank UNSPECIFIED UNSPECIFIED UNSPECIFIED Schlemmer, Stephan UNSPECIFIED orcid.org/0000-0002-1421-7281 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-256680
DOI:	10.1051/0004-6361/201629309
Journal or Publication Title:	Astron. Astrophys.
Volume:	595
Date:	2016
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics I
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language EXPLORING MOLECULAR COMPLEXITY; ROTATIONAL SPECTRUM; MICROWAVE-SPECTRUM; SAGITTARIUS B2(N2); INTERNAL-ROTATION; ORGANIC-MOLECULES; COLOGNE DATABASE; METHYL CYANIDE; ETHYL CYANIDE; BUTYRONITRILE Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/25668