ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The dynamics of the 266 nm photoinitiated reaction of 16O3 and H218O were studied using 16O3⋅H218O van der Waals dimers to orient the initial reagents. In the absence of perturbations, the geometry of the 16O3⋅H218O dimer is such that 266 nm photolysis of cluster-bound ozone initiates glancing O+H2O trajectories, with a 3 A(ring) impact parameter. Laser induced fluorescence probes show that 81±7% (2σ) of the "new''-16OH and essentially all of the "old''-18OH products were formed with v=0, with a slight preference for the Π(A') Λ doublets, and average rotational energies of 900±130 and 760±80 cm−1, respectively. Approximately 19% of the "new''-16OH products form with v=1 and average rotational energy of 930±210 cm−1. No significant OH scattering anisotropy or other vector correlations were observed. Sub-Doppler resolution experiments showed average kinetic energies for new-16OH(v=0) products about 19% higher than for old-18OH(v=0) products in the same rotational levels; increasing from values of about 500 cm−1 at low rotational levels, to about 1500 cm−1 at the highest rotational levels populated. Similar OH internal and kinetic energies were observed when the clusters were photolyzed at 281.5 nm. These dimer results are very different from those observed for the bimolecular O(1D)+H2O→2OH reaction, photoinitiated in gas phase mixtures of 16O3 and H218O. The gas phase O(1D)+H2O→2 OH reaction produces OH with pronounced recoil anisotropy, these OH products carry far more internal energy than seen in the cluster products, and there is greater disparity between the internal energies of the gas phase 16OH and 18OH products. Evidently, cooperative effects in the cluster environment result in a significant change in reaction path.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.466304
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