n-propyl cyanide vibrational states

For the gauche conformer a large number of both a- and b- type transitions were measured, for the anti conformer transitions were predominantly, but not exclusively, a- type We hence improved molecular parameters for the ground state of both anti- and gauche- n-propyl cyanide and for excited vibrational states of the gauche-conformer (v30=1, v29=1, v28=1, v30=2) and anti-conformer (v30=1, v18=1, v29=1, v30=2) with high order coupling parameter determined between v18=1 and v30=2.

Parameters are published for the first time for v18=v30=1 for the anti conformer and for v29=v30=1 for the gauche conformer. 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 380GHz.

The coupling between v30=2 and v18=1 of the anti conformer has been well characterized. An additional list of 740 lines showing probable but as yet unidentified coupling has been provided for astrophysical identification.