Knowledge Bank

The microwave spectrum of $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C$ substituted methyl cyanide $CH3C14N$ was studied for the $\nu 8=1,2$, for both single and double $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C$ substitutions, vibrational states in the frequency range of 17 to 95 gHz. The frequencies of the $1\le J\le 5$ components were measured for each vibration and these frequencies used to produce a constant set which can be used to predict overall frequencies of spectral components in the ground, $\nu 8=1,2$, up to an accuracy of 100 kHz. Previously obtained experimental data, available from the literature for the naturally occuring isotopes, and our own data for the ground will be presented and compared with the frequencies obtained from a comprehensive equation derived from perturbation techniques. Some weak interactions which have split the spectrum in the $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C$ species will be discussed. Systematic departures for the $K\ast \ast \ast =1,K=\ast \ast =-1$ and $K=\ast \ast =+1$ spectral components will be discussed.