Astronomy and Astrophysics, volume 622A, 82-82 (2019/2-1)
Rotational rest frequencies of the low lying vibrational states of n-propyl cyanide from extensive laboratory measurements up to 506 GHz.
LIU D., WALTERS A., WEHRES N., LEWEN F., SCHLEMMER S. and MULLER H.S.P.
Abstract (from CDS):
Context. The spectra of four low-lying vibrational states of both anti and gauche conformers of normal-propyl cyanide were previously measured and analyzed in two spectral windows between 36 and 127GHz. 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 114.4GHz 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 506GHz 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 506GHz.
Results. For the gauche conformer, a large number of both a- and b-type transitions were identified. For the anti conformer, transitions were predominantly, but not exclusively, a-type. We hence improved molecular parameters for the ground states of both anti- and gauche-n-propyl cyanide and for excited vibrational states of the gauche conformer (v30=1, v29=1, v30=2, v28=1) and anti conformer (v30=1, v18=1, v30=2, v29=1) with high order coupling parameters determined between v18=1 and v30=2. Parameters are published for the first time for v18=v30=1 of the anti conformer and for v29=v30=1 of the gauche conformer.
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 between v18=1 and v30=2 of the anti conformer has been well characterized. An additional list of 740 lines showing potential but as yet unidentified coupling has been provided for astrophysical identification.
© ESO 2019
molecular data - line: identification - astrochemistry - methods: laboratory: molecular - ISM: molecules - submillimeter: ISM
VizieR on-line data:
<Available at CDS (J/A+A/622/A82): table10.dat-table25.dat>
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