The chemical response of the photo-electric aerosol sensor (PAS) to different aerosol systems

A comparative study of the response of a photo-electric aerosol sensor (PAS) to different PAH aerosol systems is presented. The photo-electric activity of pure PAH particles as well as of PAH-coated graphite particles (sub-monolayer up to multi-layer coating) is determined with a miniaturized UV irradiation apparatus. The growth of layers is measured by observing the increased penetration through a screen diffusion battery. The results indicate that an analytically useful response is only obtained as long as a monolayer coating is not exceeded. Beside the extent of the π-electron system of the PAH, the molecular packing of the PAH-molecules governs the photo-electric activity.