Spin–spin coupling in 3b2 state of oxyallyl – A comparative study with trimethylenemethane

Internal splittings in the spectra are due to quantized angular momentum field of the molecule or atom, which couples through spin–spin and spin–orbit operators. These operators are subjected to recently observed close lying states of oxyallyl biradical and compared with the iso-electronic structure trimethylenemethane. With the multiconfigurational treatment of spin–spin coupling operator we predict reversal of the splitting parameter D ss of oxyallyl with reference to isoelectronic TMM spectra.