Multireference configuration interaction (MRCI) calculations have been performed for the dipole transition moments of the Noxon band, b ¹ Σ _g ⁺ –a ¹ Δ _g , and for the red and IR atmospheric emission bands, b ¹ Σ _g ⁺ –X ³ Σ _g ^- and a ¹ Δ _g –X ³ Σ _g ^- , in O ₂ in collision complexes with different solvent molecules. The spin–orbit coupling between the b ¹ Σ _g ⁺ and X ³ Σ _g ^- (M _S =0) states does not change after collision so the a–X transition borrows intensity from the collision-induced Noxon band b–a, and the b–X band borrows electric dipole transition probability from the collision-induced difference dipole moments of the b and X states. The calculations show that the b–a, a–X and b–X transition probabilities are enhanced by ca. 10 ⁵ , 10 ³ and 1.2 times by O ₂ +H ₂ collisions. An additional order of magnitude enhancement for all three transitions is possible for solvent molecules with larger polarizability than that of molecular hydrogen. The collision-induced b–a transition dipole moment depends not only on the intermolecular distance, but also on the internuclear O–O distance. Since a–X and b–a transition moments are directly connected (D _a,X =0.013iD _b,a ), the strong dependence on the O ₂ bond length leads to an additional enhancement of the (0,1) vibronic band intensity of the a ¹ Δ _g –X ³ Σ _g ^- transition. The dipole moments of the b and X states are also shown to depend on the O ₂ bond length in the collision complex, which leads to additional collision-induced enhancement of the (0,1) band of the b–X system.