Infrared spectroscopy and photochemistry at 266 nm of the ozone dimer trapped in an argon matrix

Infrared spectroscopy has been coupled with the matrix isolation technique. First, to identify the ozone dimer isolated in solid argon, and second, to investigate the mechanism of its photodissociation at 11 K using the 266 n m laser line. Identification of dimers, which are trapped in two different sites, was performed through the observation of the nu (3) asymmetric stret ching modes. By absorption of one photon, dimers are photodissociated with a high photolysis rate when compared with that of ozone monomers, suggestin g the absence of cage recombination of the photofragments. Experimental obs ervations suggest that the major pathway after photolysis is the formation of an excited transient species O-4*, which fragments into O+O-3. A two-ste p mechanism, involving the subsequent reaction of O(D-1) with O-3 formed in a first step appears unlikely. (C) 2001 American Institute of Physics.