The Microwave Spectrum of Propionitrile (C 2H 5CN) in the Frequency Range from 8 to 200 GHz

Abstract

The rotational spectrum of propionitrile (C<SUB>2</SUB>H<SUB>5</SUB>CN) has been measured in the frequency range from 8 to 200 GHz, where 1461 transitions with J ≤ 70 and K<SUB>a</SUB> ≤ 21 in the ground vibrational state have been newly assigned. A total of 2418 transitions including the 957 transitions measured previously below 610 GHz have been analyzed on the basis of a Watson A-reduced Hamiltonian. A complete set of quartic and sextic distortion constants and five octic distortion constants have been obtained with a good accuracy. In addition, newly assigned K<SUB>a</SUB> b-type transitions have enabled us to determine an octic distortion constant L<SUB>K</SUB> for the first time. The determined molecular constants can predict more precisely the frequencies of b-type transitions. These calculated frequencies will be useful in assigning interstellar spectral lines to be detected by radio telescopes.