Quantum yields for Cl(²P_{3/2, 1/2}), ClO and O(³P) in the photolysis of chlorine nitrate at 308 nm

Quantum yields have been measured for chlorine nitrate photolysis at 308 nm using resonance fluorescence to detect Cl and O(³P). The addition of NO allowed ClO to be detected as Cl atoms. The quantum yields were determined to be: Cl 0.80 ± 0.20, O(³P) ≤0.05 and ClO 0.28 ± 0.12. Approximately one third of the chlorine atoms are formed in the excited spin-orbit state Cl(²P_1/2). A large proportion of the ClO radicals were found to be formed in excited vibrational states which react more slowly with NO than ground-state ClO, and are quenched slowly by N₂. The yields of Cl and ClO were found to be independent of total pressure up to 100 Torr. Rate coefficients were also measured for the reactions of chlorine nitrate with Cl atoms, k₃ = (9.1 ± 1.2) × 10^-12 cm³ molecule^-1 s^-1 and O atoms, k₄ = (2.4 ± 0.4) × 10^-13 cm³ molecule^-1 s^-1.