Hyperfine Structure in the Microwave Spectrum of NH2D

Abstract

Hyperfine structure in the 3₁₃→3₀₃ rotation—inversion transition of deuterated ammonia NH₂D at 18 807.7 Mc/sec has been studied with a beam maser microwave spectrometer giving a linewidth of 7 kc/sec. All details of the observed hyperfine structure have been accounted for in terms of the various quadrupole, spin—rotation, and spin—spin interactions of the four coupling nuclei. The hyperfine coupling constants which have been determined with the aid of a digital electronic computer are, for the 3₁₃ state: (eq_JQ)_D=—62.5±1.0 kc/sec, C_D=—2.7±0.3 kc/sec, C_H=—13.6±0.5 kc/sec; and for the 3₀₃ state: (eq_JQ)_D=—73.9±1.0 kc/sec, C_D=—2.7±0.3 kc/sec, C_H=—12.3±0.5 kc/sec. On the assumption that the electric field at the deuteron is cylindrically symmetric about the N—D bond direction ξ, we find that (eV_ξξQ)_D=282±12 kc/sec, or V_ξξ=1.38±0.06×10¹⁵ statV/cm², where V_ξξ is the second derivative of the electrostatic potential along ξ.