title: Heterogeneous reactivity of chlorine atoms with ammonium sulfate and ammonium nitrate particles.
abstract: In this laboratory study, model particles of ammonium sulfate (AS) and ammonium nitrate (AN) were exposed to chlorine atoms and uptake experiments were performed in a coated wall flow tube reactor coupled to a molecular beam mass spectrometer. The reactive surfaces were prepared by coating the inner surface of the reactor using two different methods: either by depositing size-selected particles on the halocarbon wax or by spray depositing thin films using a constant output atomizer. The observed uptake coefficients vary for (NH(4))(2)SO(4), ranging from γ(Cl)(AS)≈ 1 × 10(-3) for size-selected particles to γ(Cl)(AS)≈ 6 × 10(-2) for thin films prepared by spray. An uptake coefficient of γ(Cl)(AN)≈ 2.5 × 10(-3) of Cl˙ on size-selected NH(4)NO(3) particles was measured. A heterogeneous recombination of Cl atoms to from Cl(2) molecules was observed for the two surfaces. Furthermore, an ageing process was observed for AS particles, this phenomenon leading to the formation of new chlorine species on the solid substrate.
authors.affiliation: Laboratoire de Physico-Chimie des Processus de Combustion et de l'Atmosphère, UMR CNRS Lille, Université Lille1-Sciences et Technologies, France.
authors.forename: Raluca
authors.initials: R
authors.lastname: Ciuraru
authors.forename: Sylvie
authors.initials: S
authors.lastname: Gosselin
authors.forename: Nicolas
authors.initials: N
authors.lastname: Visez
authors.forename: Denis
authors.initials: D
authors.lastname: Petitprez
mesh_terms: D000645:Ammonium Sulfate / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D009566:Nitrates; D002713:Chlorine; D000645:Ammonium Sulfate; C006568:ammonium nitrate