Fluorescence and quenching of O2(1Δg) and [O2(1Δg)]2 in liquid oxygen

Liquid oxygen, oxygen/nitrogen, and oxygen/argon mixtures were excited by 1.060 μ radiation from a Nd:glass laser. The fluorescence decay was monitored at 6340 Å, 7030 Å, 1.27 μ, and 1.58μ. The quenching rate coefficient of O₂(a ¹Δ_g) by ${\mathrm{O}}_2{\mathrm{(X\hspace{0.17em}}}^3{\Sigma }_g^{-})$ was found to be 1.0±0.1×10⁻¹⁸ cm³/sec at 77°K. The temperature variation between 77 and 322°K is consistent with 2.2×10⁻¹⁸ (T/300)^1/2 cm³/sec. Quenching by N₂ and argon was at least an order of magnitude slower. In every case the decay of [O₂(¹Δ_g)]₂ was twice as fast as that of O₂(¹Δ_g) alone, indicating that even at liquid nitrogen temperature [O₂(¹Δ_g)]₂ is in rapid collisional equilibrium with O₂(¹Δ_g).