Femtosecond reaction dynamics of OClO in a supersonic molecular beam are reported. The system is excited to theAthinsp;2A2state with a femtosecond pulse, covering a range of excitation in the symmetric stretch betweenv1=17 tov1=11(308ndash;352 nm). A timehyphen;delayed femtosecond probe pulse ionizes the OClO, and OClO+is detected. This ion has not been observed in previous experiments because of its ultrafast fragmentation. Transients are reported for the mass of the parent OClO as well as the mass of the ClO. Apparent biexponential decays are observed and related to the fragmentation dynamics: thinsp; OClO+hngr;rarr;(OClO)Dagger;ast;rarr;ClO+O thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;thinsp;rarr;Cl+O2thinsp;. thinsp; Clusters of OClO with water (OClO)n(H2O)mwithnfrom 1 to 3 andmfrom 0 to 3 are also observed. The dynamics of the fragmentation reveal the nuclear motions and the electronic coupling between surfaces. The time scale for bond breakage is in the range of 300ndash;500 fs, depending onv1; surface crossing to form new intermediates is a pathway for the two channels of fragmentation: ClO+O (primary) and Cl+O2(minor). Comparisons with results ofabinitiocalculations are made.
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