Time-resolved Raman observation of the aqueous O 3

A Raman study of the O −+O 2→O 3 − reaction in aqueous solution is reported. The reaction half-period was measured as ∼ 200 ns in oxygen saturated solution at room temperature. Spectroscopic evidence for the O 3 −-solvent coupled vibrations has been found. The harmonic frequency ( Ω e ) of the O 3 − symmetric stretch in aqueous solution, 1058 cm −1, is 30–40 cm −1 higher, and the anharmonicity constant ( Ω eχ e ), 9 ± 2 cm −1, about twice as large as compared to the O 3 −1 inbedded in crystalline matrices or bonded to a counter ion. The O 3 −→2O+O − dissociation energy is drastically lowered on hydration.