Photodissociation Processes of Ozone in the Huggins Band at 308−326 nm: Direct Observation of O(1D2) and O(3Pj) Products

Both O( 1 D) and O( 3 P j ) atoms produced in the photodissociation of O 3 were directly detected, using a vacuum ultraviolet laser-induced fluorescence technique. The photofragment yield spectra of the O( 1 D) and O( 3 P j ) atoms were recorded at 298 K, scanning the photodissociation laser wavelength across the range 308−326 nm in the Huggins band system of O 3 . The photofragment yield spectrum for O( 3 P j ) has the vibrational structure as appearing in the absorption spectrum in the Huggins band, while the spectrum for O( 1 D) is smooth and has no structure. The wavelength dependence of the quantum yield for O( 1 D) from the O 3 photolysis exhibits a dip at every peak of the vibrational structure in the absorption spectrum in the Huggins band. The partial cross sections for the O( 1 D) production process in the photoabsorption of O 3 were determined. The existence of the tail around 315 nm in the wavelength dependence of the quantum yield of O( 1 D) produced from O 3 photolysis was verified. Our results indicate that the tail arises predominantly from the hot-band excitation of O 3 .