Fig. 2.

Conceptual model for distribution of S MIF in products of sulfur photochemistry. Arrows may represent complex, multistep reaction pathways rather than single reactions. S MIF in the photoproducts and in the residual SO₂ are shown in red. At wavelengths less than ∼220 nm, SO₂ dissociates and photoproducts are fractionated by a factor, E^D. Photoexcitation at wavelengths greater than ∼260 nm and subsequent reaction of the excited SO₂ may lead to a variety of final products. These photoproducts are fractionated by a different factor, E*. SO₃ (and subsequently H₂SO₄) may form by direct oxidation of SO₂, in which case the oxidation products will carry S MIF similar to the SO₂. The fractions of H₂SO₄ and S₈ formed by reaction of photoexcited SO₂ are denoted and , respectively.