Rotational components of the v10 = 1 and ground vibrational levels of propyne with 13C substitutions for the frequency range 17–75 GHz

Abstract The microwave spectrum of 13 C-substituted propyne was studied for the v 10 = 1 and ground vibrational states in the frequency range of 17 to 75 GHz for the naturally abundant species. Only a few of the ground vibrational components have been reported in the literature because of the weakness of the spectral lines. Those which have been reported were remeasured and the results presented for comparison with our own. The frequencies of 0 ≤ J ≤ 4 components were measured for naturally occurring 13 C species and these frequencies were used to produce a constant set which can be used to predict overall frequencies of spectral components in the ground, v 10 = 1, 2 up to an accuracy of a few hundred kilohertz, thus enabling ready assignment of the quantum sets. Previously obtained experimental data for the ground vibration available from the literature and our own data for the ground and v 10 = 1 are presented and compared with the frequencies obtained from a comprehensive equation derived from perturbation techniques.