Time-resolved Raman observation of the aqueous O3−

A Raman study of the O−+O2→O3− 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 O3−-solvent coupled vibrations has been found. The harmonic frequency (Ωe) of the O3− symmetric stretch in aqueous solution, 1058 cm−1, is 30–40 cm−1 higher, and the anharmonicity constant (Ωeχe), 9 ± 2 cm−1, about twice as large as compared to the O3−1 inbedded in crystalline matrices or bonded to a counter ion. The O3−→2O+O− dissociation energy is drastically lowered on hydration.