The infra-red L.M.R. spectrum of SeH in theX2Π state

Abstract
Magnetic dipole transitions between the 2Π1/2 and 2Π3/2 components of the ground state of SeH have been observed at about 1780 cm-1 in a L.M.R. experiment using a CO laser. Transitions have been detected for the four most abundant natural isotopes of Se. The transition frequencies depend primarily on the magnitude of the spin-orbit coupling constant and have been analysed in conjunction with data from the E.P.R. spectrum to yield The admixture of other electronic states by spin-orbit coupling has been investigated to third order in perturbation theory and found to produce significant effects.