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Paper
Phys. Chem. Chem. Phys., 2006, 8, 2506 - 2512, DOI: 10.1039/b602704k
Ozonolysis and photolysis of alkene-terminated self-assembled monolayers on quartz nanoparticles: implications for photochemical aging of organic aerosol particles
Jiho Park, Anthony L. Gomez, Maggie L. Walser, Ao Lin and Sergey A. Nizkorodov
Photolysis of alkene-terminated self assembled monolayers (SAM) deposited on Degussa SiO2 nanoparticles is studied following oxidation of SAM with a gaseous ozone/oxygen mixture. Infrared cavity ring-down spectroscopy is used to observe gas-phase products generated during ozonolysis and subsequent photolysis of SAM in real time. Reactions taking place during ozonolysis transform alkene-terminated SAM into a photochemically active state capable of photolysis in the tropospheric actinic window (
> 295 nm). Formaldehyde and formic acid are the observed photolysis products. Photodissociation action spectra of oxidized SAM and the observed pattern of gas-phase products are consistent with the well-established Criegee mechanism of ozonolysis of terminal alkenes. There is strong evidence for the presence of secondary ozonides (1,3,4-trioxalones) and other peroxides on the oxidized SAM surface. The data imply that photolysis plays a role in atmospheric aging of primary and secondary organic aerosol particles.
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