BRANCH INTENSITIES IN THE MAGNETIC DIPOLE ROTATION-VIBRATION SPECTRUM OF THE OXYGEN MOLECULE

The theory of branch line strengths for a magnetic dipole rotation-vibration spectrum in a (3) Sigma diatomic state is discussed in the context of the oxygen molecule. It is argued that, in contradistinction to the electric dipole case, magnetic dipole rovibrational transitions can occur only through indirect mechanisms. One possible mechanism, that of vibration-rotation interaction, is examined in detail and shown to be unimportant at least in a first-order calculation. The departure of the (3) Sigma state from a pure Born-Oppenheimer state is treated phenomenologically and shown to result in the appearance of two vibronic transition moments, M \ and M perpendicular to (the former arising only in the second order), in the branch line strength formulae. The available intensity data on O-2 are used to generate an intensity listing for lines in the fundamental band.