Photochemical ozone and nitric oxide formation in air--nitrogen dioxide mixtures containing sulfur dioxide or chlorine.

Experiments were performed to investigate the effects of sulfur dioxide (O-10 ppm) and chlorine (O-15 ppm) on ozone and nitric oxide concentrations in irradiated mixtures of nitrogen dioxide (1-5 ppm) and air. The mixtures were irradiated by ultraviolet fluorescent lamps while flowing at a steady speed through a 9 m long, 15.2 cm i.d. Pyrex tube. The presence of sulfur dioxide produced no measurable change in the ozone and nitric oxide con~ntrations. The addition of small quantities of chlorine increased the ozone con~ntration in much the same manner as the addition of a hydr~rbon. A reaction model was developed for the chlorine-nitrogen dioxide-air mixtures. The observed increase in ozone concentration could only be predicted if the following two reactions were included : Cl00 + NO -+ NO2 + Cl0 and Cl00 + NO -+ GINO + OZ. Significant quantities of unexpected condensation nuclei were also observed in the chlorine-nitrogen dioxide-air mixtures.