Fine structure and perturbations in the d (3p) 3Πu states of H2 and D2

Abstract

Previous measurements of the so‐called spin‐orbit and spin‐spin coupling constants, orbital angular momentum g factor, and the anisotropy of the magnetic susceptibility of H₂ and D₂ in the d (3p) ³Π_u state are analyzed according to the theory of the preceding paper [T. A. Miller, J. Chem. Phys. 59, 4078 (1973)]. This analysis yields fine structure parameters which are free of the effects of perturbation or Born‐Oppenheimer breakdown. These parameters are compared to recent theoretical calculations, and quite good agreement is found except for the spin‐orbit coupling constant. However, the discrepancy between theory and experiment is much larger than the experimental error for all the parameters except the least accurately measured hyperfine coupling constants. The analysis also determines values for regular and irregular heterogeneous perturbations of the d (3p) ³Π_u state, as well as showing that homogeneous perturbations are not significantly greater than the experimental error of the parameters. The heterogeneous perturbations are used to obtain approximate values of matrix elements between the d (3p) ³Π_u state and ³Σ_u⁺ states. These matrix elements test the hypothesis of pure precession, the variability of perturbations with internuclear distance, and the number of perturbing states.