Microwave Spectrum and Molecular Constants of Hydrogen Cyanide

Precision measurements of the frequencies of the $J=0\mathrm{}\to 1$ transition of H${\mathrm{C}}^{12}$ ${\mathrm{N}}^{14}$, H${\mathrm{C}}^{13}$ ${\mathrm{N}}^{14}$, D${\mathrm{C}}^{12}$ ${\mathrm{N}}^{14}$, and D${\mathrm{C}}^{13}$ ${\mathrm{N}}^{14}$ have been made with multiples of a 10-mc/sec. frequency monitored by Station WWV. The $B_0$ and ${\mathrm{I}}_{\mathrm{o}}$ values are, respectively: 44300.83 mc and ${18.93}_{790}$ g ${\mathrm{cm}}^2$×${10}^{-40\mathrm{}}$ for H${\mathrm{C}}^{12}$ ${\mathrm{N}}^{14}$; 43154.83 and ${19.44}_{080}$ for H${\mathrm{C}}^{13}$ ${\mathrm{N}}^{14}$; 36207.40 and ${23.17}_{108}$ for H${\mathrm{C}}^{12}$ ${\mathrm{N}}^{14}$; 35587.57 and ${23.57}_{465}$ for D${\mathrm{C}}^{13}$ ${\mathrm{N}}^{14}$. The interatomic distances determined are $d_{\mathrm{CH}}=1.061\mathrm{}$ A and $d_{\mathrm{CN}}=1.157\mathrm{}$ A. The nuclear quadrupole coupling of ${\mathrm{N}}^{14}$ is determined as 4.58±0.05 mc/sec.