Rotational components of the v8 = 1, 2, and 3 and ground vibrational levels of CH3C15N for the frequency range 17–75 GHz

Abstract The microwave spectrum of methyl cyanide CH 3 C 15 N was studied for the v 8 = 3 vibrational state in the frequency range of 17 to 75 GHz. In addition, some rotational components for the ground, v 8 = 1 and 2 were remeasured and these results compared to those found in the literature. The frequencies of 42 components were measured 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 8 = 1, 2 up to an accuracy of 100 KHz and those for v 8 = 3, 4 up to an accuracy of 150 KHz. Previously obtained experimental data, available from the literature, and our own data for the ground, v 8 = 1 and 2, and the new data for v 8 = 3 are presented and compared with the frequencies obtained from a comprehensive equation derived from perturbation techniques.