Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals Université de Lyon, Lyon, 69626, France; université Lyon 1, Lyon, 69626, France; CNRS, INSU, UMR5256, IRCELYON, Institut de recherches sur la catalyse et l'environnement de Lyon, Villeurbanne, 69626, France
Received: 12 Feb 2009 – Published in Atmos. Chem. Phys. Discuss.: 24 Mar 2009 Abstract. The interactions between triplet state benzophenone and halide anion species
(Cl, Br and I have been studied by
laser flash photolysis (at 355 nm) in aqueous solutions at room temperature.
The decay of the triplet state of benzophenone was followed at 525 nm.
Triplet lifetime measurements gave rate constants, kq (M−1 s), close to diffusion controlled limit for iodide (~8×109 M−1 s), somewhat less for bromide (~3×108 M−1 s) and much lower for chloride (<106 M−1 s). The halide (X−) quenches the triplet state;
the resulting product has a transient absorption at 355 nm and a lifetime
much longer than that of the benzophenone triplet state, is formed. This
transient absorption feature matches those of the corresponding radical
anion (X2). We therefore suggest that such
reactive quenching is a photosensitized source of halogen in the atmosphere
or the driving force for the chemical oxidation of the oceanic surface micro
Revised: 09 Jun 2009 – Accepted: 12 Jun 2009 – Published: 02 Jul 2009
Citation: Jammoul, A., Dumas, S., D'Anna, B., and George, C.: Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals, Atmos. Chem. Phys., 9, 4229-4237, doi:10.5194/acp-9-4229-2009, 2009.