PHOTOLYSIS OF OZONE AT 693 NM IN SOLID OXYGEN - ISOTOPIC EFFECTS IN OZONE REFORMATION

The photodissociation of O-18(3) (fully substituted ozone or 888) in t he visible region has been studied in a natural oxygen matrix at 10 K combining 693 nm laser irradiation with infrared absorption spectrosco py. Ozone 888 is converted to the (unsymmetrical and symmetrical) 668 and 686 species which are further converted to the normal 666 species through the exchange of O-18 with O-16 atoms. The overall photodissoci ation of 888 is a first-order process and a reasonably simple model is proposed which reproduces satisfactorily the observed kinetic results . The value of the photolytic kinetic rate constant suggests an increa se in the absorption cross section for the visible band with respect t o that measured in the gas phase, The experiments suggest an enhanced formation rate of the unsymmetrical 668 species with respect to the sy mmetrical species 686 during the O-18 oxygen atom recombination with t he matrix O-16(2) molecules. (C) 1997 Elsevier Science B.V.