Theory of Magnetic Hyperfine and Zeeman Interactions for Hund's Case (b), Applied to thecΠu3State ofH2

Abstract
The theory of hyperfine interactions in a homonuclear diatomic molecule is re-examined for Hund's coupling case (b). Diagonal and off-diagonal matrix elements among J, the fine-structure levels, are explicitly given for an arbitrary electronic state and spin. Expressions for the Zeeman interactions at small magnetic fields are derived, when J is no longer a good quantum number. This theory is applied to the cΠu3(1s2p) state of H2, and the previous discrepancy between theoretical and experimental gF values is resolved.