Measurements of Hyperfine Structure in NH2D

Abstract

Hyperfine structure on the 4₁₄ – 4₀₄ rotation–inversion transition in NH₂D was measured with a two‐cavity maser spectrometer with 350‐Hz linewidth. A reasonably good fit to the observed transitions is obtained by including the nitrogen quadrupole interaction, the nitrogen spin–rotation interaction, the deuteron quadrupole interaction, the deuteron spin–rotation interaction, and the nitrogen–deuteron spin–spin interaction in the Hamiltonian. The values of the coupling constants obtained are: for the 4₁₄ state ${\mathrm{(eq}}_J{\mathrm{Q)}}_N\text{\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}1895.65\hspace{0.17em}±\hspace{0.17em}0.7}\mathrm{kHz}$ , ${\mathrm{(eq}}_J{\mathrm{Q)}}_D\text{\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}75.78\hspace{0.17em}±\hspace{0.17em}0.7}\mathrm{kHz}$ , and for the 4₀₄ state ${\mathrm{(eq}}_J{\mathrm{Q)}}_N\text{\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}1811.55\hspace{0.17em}±\hspace{0.17em}0.7}\mathrm{kHz}$ , ${\mathrm{(eq}}_J{\mathrm{Q)}}_D\text{\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}80.13\hspace{0.17em}±\hspace{0.17em}0.7}\mathrm{kHz}$ , and for the values of the other parameters averaged over these states $C_N\text{\hspace{0.17em}=\hspace{0.17em}5.027\hspace{0.17em}±\hspace{0.17em}0.18}\mathrm{kHz}$ , $C_D\text{\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}2.33\hspace{0.17em}±\hspace{0.17em}0.18}\mathrm{kHz}$ ,and $D_{\mathrm{ND}}\text{\hspace{0.17em}=\hspace{0.17em}0.307\hspace{0.17em}±\hspace{0.17em}0.70}\mathrm{kHz}$ . The rotation–inversion frequency for this transition is 25 023 794.706 ± 0.07 kHz.