Collision induced absorption in the a1Δ(v = 2) ← X3Σ−g(v = 0) band of molecular oxygen

Using cavity ring-down spectroscopy we measured the collision induced absorption spectrum associated with the a1Δ(v = 2) ← X3Σ−g(v = 0) band of oxygen near 922 nm both in pure oxygen and in mixtures of oxygen and nitrogen. For pure oxygen, we report for this band an integrated absorption of (1.56 − 0.04/+0.40) × 10−5 cm−2 amg−2. We find that collisions between oxygen and nitrogen do not result in any measurable CIA signal. At 1 bar of oxygen, this collision induced transition is much stronger than the allowed magnetic dipole and electric quadrupole transitions.