Microwave optical double resonance spectrum of NH2. I. Ground state, 14N hyperfine coupling constants, and spin rotation constants

Abstract

Magnetic dipole allowed transitions between the two J components of the same rotational state in the ground vibronic state of NH₂ have been detected using microwave optical double resonance. The hyperfine structure of some of these transitions have been analyzed to yield values for the ¹⁴N magnetic coupling constants (in MHz) of (O)_I=27.9 (0.6), (aa)_I=−43.3 (1.5), and (cc)_I=87.4 (0.9), where the quoted error in parentheses is three standard deviations. In addition, a preliminary analysis of the fine structure splittings determines the spin rotation constants (in MHz) to be A_s=−9290.0 (160), B_s=−1331.9 (38), and C_s=3.9 (57). A poor fit of the fine structure arises from an inadequate Hamiltonian, and the statistical uncertainty quoted for these parameters is probably meaningless. The derived constants for the gas phase are compared with the available solid state ESR data as well as some theoretical studies.