Theory of the radiative lifetime of the 3B1 state of SO2

Interchange and many-body perturbation theory are applied to the calculation of the radiative lifetime of the ³B₁ state of SO₂. The radiative lifetime of ³B₁ SO₂ is predicted to be 7.6 msec, in excellent agreement with the experimental collision-free phosphorescence lifetime. As a separate calculation, interchange perturbation theory is used to determine the radiative lifetime of the ¹A₁ state of CH₂.