Electron resonance of gaseous diatomic hydrides II. Rotational constant, Λ-doubling, hyperfine structure and dipole moment of SeH and SeD

The electron resonance spectra of the J = 3/2 and J = 5/2 rotational levels of the 2II 3/2 state of SeH and the J = 3/2 rotational level of the 2II3/2state of SeD are described. Values of the rotational constant and Λ-doubling parameters are determined. Evidence is found for a tensorial interaction of the spin and magnetic field, arising from the gauge invariance requirement of the spin-orbit coupling Hamiltonian. Hyperfine structure from 77Se is observed, and the hyperfine coupling constants are determined. The effect of an electric field on the spectra is analysed and the electric dipole moment determined.