The formation of ClOO following the photoexcitation of aqueous OClO studied by two-color, time-resolved resonance Raman spectroscopy

The photochemistry of chlorine dioxide (OClO) is investigated by two-color time-resolved resonance Raman spectroscopy. Pump and probe wavelengths of 3 90 and 260 nm, respectively, are used to monitor photoproduct formation fol lowing aqueous OClO photoexcitation. Depletion and subsequent recovery of t he OClO scattering intensities is observed consistent with subpicosecond re formation of OClO via geminate recombination of the primary photoproducts. Intensity is observed at 1442 cm(-1) consistent with ClOO formation that ap pears and decays with time constants of 27.9 +/- 4.5 ps and 398 +/- 50 ps, respectively. The results presented here represent the first direct evidenc e for ClOO formation following the photoexcitation of aqueous OClO. (C) 200 0 American Institute of Physics. [S0021-9606(00)52302-2].