Rotation—Vibration Interaction and Other Corrections to the Spin Doublet Separation in 2Π Diatomic Molecules

Abstract

The effect of rotation—vibration interaction on the spin doublet separation in ²Π states of diatomic molecules is treated. Almy and Horsfall's refinement of Hill and Van Vleck's treatment is questioned and an alternative approach making use of Dunham's treatment of ¹Σ diatomic molecules is used. The J dependence of the spin‐orbit coupling constants is included in the discussion. Vibrational wavefunctions (including rotation—vibration interaction) and matrix elements are discussed. Additional corrections arising from the Λ doubling and from the spin—rotation interaction ΓN·S are briefly considered. A comparison of the results of this work with experimental spin doublet separation leads to better agreement between theory and experiment for the examples treated.