Knowledge Bank

Nitric Oxide is a good Hund’s case (a) molecule with a doublet pi ($\pi$) ground electronic state, an electronic magnetic moment of about one Bohr magneton, and a nuclear spin of unity. In anticipation of the exploration of its rich radiofrequency spectrum I have calculated the mixing of the hyperfine-structure states due to the interaction of the magnetic moment with a uniform magnetic field. The hyperfine-structure and Zeeman energies are taken as small compared to the spacing of the two components of a given multiplet, but not with respect to the spacing of adjacent components which differ only in the quantum number J. The influence of these neighbouring states is taken into account via second-order degenerate perturbation theory, yielding a quadratic dependence on field intensity. Results are obtained for those magnetic substates which originate in the J = 1/2, J = 3/2, and J = 5/2 zero-field levels, and these are compared with available experimental data.