Petroleum pollution sensing at ppb level using quartz crystal resonators sputtered with porous polyethylene under photo-excitation

Radio-frequency (r.f.) sputtering of a porous polyethylene (PE) disk made b y sintering PE granules can be used to form hydrocarbon-polymer films appli ed as the chemical-sensing overlayers of quartz crystal resonator sensors t hat can detect petroleum hydrocarbon vapors at low parts-per-billion (ppb) levels. The vapor-sorption capabilities of these films are profoundly affec ted by the sputtering method used; they are enhanced by photo-excitation th rough irradiation using ultraviolet (UV) light, and reduced by carbonizatio n induced by long-term processing or by water-treatment. The RE films, espe cially photo-excited PE film, are characterized by a smooth surface, a high atomic density with a high hydrogen content, and dangling-bond longevity. Photo-excited RE film are capable of detecting linear hydrocarbon (> C-12) vapors below the ppb level. Pre-sorption with water vapor at 9% relative hu midity (RH) can enhance the sensing abilities of sensors for petroleum hydr ocarbons. The effect of this water treatment on petroleum hydrocarbon sorpt ion is especially prominent for D-phenylalanine-sputtered film. (C) 2000 El sevier Science S.A. All rights reserved.