Knowledge Bank

The microwave spectra of the isotopic species $K^{13} $CN and $KC15N$ have been determined by molecular beam electric resonance spectroscopy. The seeded beam technique was used to concentrate the population in the lower rotational and vibrational levels. For both isotopic species we observed about 20 rotational transitions originating in the ground vibrational state in the frequency range 12 to 38 GHz and determined the three rotational, as well as the five quartic centrifugal distortion constants. The rotational constants of the normal isotopic species $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ and of the $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">15</mrow>}N$ substituted species were used to determine the effective structure for the ground vibrational state and the substitution structure. The substitution structural parameters in {\AA} are $rCN=1.171(2),rCK=2.711(5),rKN=2.532(5)$.