Ab initio and variational transition state approach to atmospheric photooxidation: Mechanism and kinetics for the reaction of HN3 with OH radicals

Azide is readily protonated in the aqueous environment to yield volatile hydrazoic acid (HN3) that can then pose an airborne hazard. The reaction with OH radicals is likely tropospheric removal process of HN3. In this Letter, ab initio molecular orbital calculations have been employed to investigate the mechanism for the atmospheric photooxidation of HN3 by OH radicals. The rate constants have been deduced by canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) correction over a wide temperature range of 200–3000 K. The calculated results were in reasonable agreement with experimental measurement.