Photodissociation of CSCl_2 at 235 nm: Kinetic energy distributions and branching ratios of Cl atoms and CSCl radicals

摘要

The photodissociation dynamics of thiophosgene (CSCl_2) and the respective branching ratios of both dissociation products Cl and CSCl have been studied by 3D imaging of the photodissociation product chlorine in its ground state ~2P_(3/2)[Cl] and excited spin-orbit state ~2P_(1/2) [Cl~*] employing the resonance enhanced multiphoton ionization and time-of-flight technique at a dissociation wavelength of about 235 nm. A novel technique is applied where the complete three-dimensional (3D) molmentum vector of a reaction product is directly determined. The kinetic energy distribution (KED) for Cl~* is observed for the first time. The obtained KEDs of Cl and Cl~* are different in the low kinetic energy range due to the correlating state of the partner fragment CSCl. In the case of ground state Cl the CSCl partner radical is produced in the ground X, A, and B states with a contribution of 4 +- 0.5%, 60 +- 5%, and 36 +- 3% respectively. In the case of Cl~* the corresponding CSCl is produced with a contribution of 7.5 +- 0.5% in the ground X, 71.5 +- 5.5% in these A, and 21 +- 1.5% in state B. The yield of Cl~*, PHI(Cl~*) = P(Cl~*)/[P(Cl) + P(Cl~*)], was found to be 0.47. No significant velocity dependence of the anisotropy parameter bete could be observed. The mean value + 0.03 suggests a decay on the B (A_1) surface.