Oxidation of polystyrene aerosols by VUV-photolysis and/or ozone.

Aerosols of submicron polystyrene particles were oxidized by either vacuum-ultraviolet (VUV) irradiation in the presence of molecular oxygen (O(2)) and/or by ozone (O(3)). Different degrees of oxidation and oxidative degradation were reached by VUV-photolysis depending on radiant energy, O(2) and H(2)O concentrations in the bulk gas mixture as well as on particle diameter. The same functionalization was obtained by exposing the aerosol to O(3), however, oxidation, in particular oxidative degradation, was less efficient.

Fragmentation and bond strength of airborne diesel soot agglomerates.

Background: The potential of diesel soot aerosol particles to break up into smaller units under mechanical stress was investigated by a direct impaction technique which measures the degree of fragmentation of individual agglomerates vs. impact energy. Diesel aerosol was generated by an idling diesel engine used for passenger vehicles.