Kinetic study of the reactions of hydrogen and deuterium atoms with HBr and DBr by time-resolved resonance fluorescence

Abstract

We describe a kinetic investigation of H and D atoms in their electronic ground states by the method of time-resolved Lyman-α resonance fluorescence in the vacuum ultraviolet following pulsed photochemical generation of the atoms. The method involved repetitive pulsing, photon counting and signal averaging. Absolute rate constants (k/cm³ molecule^–1 s^–1, 300 K) are reported for the following reactants; H + H₂S, (8.6 ± 0.5)× 10^–13; D + D₂S, (7.9 ± 0.4)× 10^–13; H + HBr, (6.0 ± 0.1)× 10^–12; D + HBr, (4.1 ± 0.1)× 10^–12; H + DBr, (4.7 ± 0.1)× 10^–12; D + DBr, (2.7 ± 0.1)× 10^–12. The rates for the reactions with HBr and DBr are compared with values previously derived from e.p.r. measurements on H and D in a flow discharge system.