| Autor: |
Chichinin, Alexei, EinfeldPresent address: BASF AG, Tina S., Ludwigshafen, 67056, Germany., Gericke, Karl-Heinz, Grunenberg, Jörg, Maul, Christof, SchäferPresent address: Max-Planck-Institut für biophysikalische Chemie, Lars V., Göttingen, 37070, Germany. |
| Zdroj: |
Physical Chemistry Chemical Physics (PCCP); 2004, Vol. 7 Issue: 2 p301-309, 9p |
| Abstrakt: |
New theoretical and experimental results for the ultraviolet photodissociation dynamics of thionyl chloride SOCl2 are presented and combined with existing data from a variety of sources in order to provide a unified view of the photodissociation dynamics of SOCl2. Time-dependent density functional theory on the basis of the hybrid-type B3LYP functional was employed to calculate vertical excitation energies for the SOCl2parent molecule up to 6.3 eV. Three-dimensional 3D imaging of photofragments was performed for a dissociation wavelength of 235 nm. Atomic chlorine fragments were observed in the 2P32ground state Cl and the 2P12excited spin–orbit state Cl by employing resonance enhanced multi-photon ionization REMPI and time-of-flight TOF techniques. State-specific speed distributions and the speed dependence of the βanisotropy parameter were obtained from the full 3D momentum vector distribution by appropriate projection methods. Bimodal speed distributions for both spin–orbit states are evidence of a competition between the radical SOCl2→ SOCl ClCl and the three-body decay channel SOCl2→ SO 2 ClCl. No evidence of the molecular fragmentation channel SOCl2→ SO Cl2 was found. With increasing fragment speed the βanisotropy parameter increases from 0.1 to 0.85 and 0.68 for Cl and Cl, respectively, suggesting fragmentation viaan excited A′ state for slow fragments and viaan A″ state for fast fragments. The calculations allow for the first time to interpret all previous and new experimental data for the ultraviolet photodissociation of SOCl2by assuming simultaneous excitation of several excited electronic states giving rise to competing dissociation channels. |
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