Microwave spectrum of propionitrile: Determination of the quartic and sextic centrifugal distortion constants

The ground state rotational spectrum of propionitrile has been reinvestigated between 8 and 250 GHz. A total of 218 transitions with J ≤ 48 and K ≤ 21 have been assigned. These data have been analyzed in terms of a reduced Hamiltonian similar to, but different from that proposed by Watson. All the determinable constants up to the sextic terms have been significantly determined. The rotational constants are (in MHz):

$\text{A}{}^{\mathrm{\prime }}\text{= 27 663.683, B}{}^{\mathrm{\prime }}\text{= 4714.187 8, and C}{}^{\mathrm{\prime }}\text{= 4235.085.2}$