Studies of ground-state 2P halogen atoms using atomic resonance absorption

Abstract

Known concentrations of ground-state Br, Cl and I ²P atoms can be formed by the rapid stoichiometric reactions: [graphic omitted] k₁, defined by –½[Br₂]^–1d ln[O]/dt, is reported as (8.7 ± 3.0)× 10^–12 cm³ molecule^–1 s^–1 at 298 K. These reactions provide simple absolute calibrations for resonance line absorption intensities with Br, Cl and I ²P atoms in discharge-flow systems. Photolysis of Br₂ and of ICl by H λ 121.6 nm radiation present in the atom resonance lamps leads to the formation of excited Br and I atoms. The effects of these phenomena on measurements of atom concentrations by resonance absorption are considered.