The relative importance of the various intermediate species in olefin removal reactions in photochemical smog.

Abstract

Abstract Computer simulations have been made of the chemical changes which occur in smog chamber experiments employing NO-NO2-trans-2-butene-air mixtures. The results indicate that significant differences are expected between experiments carried out with steady illumination and with periods of illumination punctuated with relatively long dark periods. In particular the ozone, olefin, NOX concentration-time profiles are altered appreciably by using the alternative irradiation techniques. When proper account is taken of the effect, an excellent match is had between the present computer simulation and the experimental studies of Tuesday in which a light-dark period cycle was employed. The computer simulation of this system with steady illumination provides a basis for judging the relative importance toward olefin attack of the various possible reactive intermediates in this system. O(3P), O3, and OH species all seem to be important during some stage of the olefin-NO-photo-oxidation sequence. HO2 and CH3O rad...