ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Translational energy (Et ) spectra of Cl and HCl fragments from vinylchloride, trans-dichloroethylene, cis-dichloroethylene, and 1,1'-dichloroethylene have been measured for the π*←π excitation at 193 nm. Et distribution and angular dependence of the Cl fragment indicate that the two-center dissociation occurs in a time faster than a rotation period and the recoiling organic radical (the counter fragment) is highly vibrationally excited. In dichloroethylenes, the presence of a second channel producing Cl atoms has been confirmed and attributed to the dissociation from the lower (n,σ*) state through a (π,σ*) state. The Et distribution of HCl fragments is nonstatistical and found to converge to null population at an energy less than half of the total available energy. This convergence point coincides with the value of the local available energy for the elimination reaction (activation energy —ΔH0reaction ). The yield of HCl molecules relative to Cl atoms is estimated to be ∼1.1 for vinylchloride. High efficiency of the HCl elimination is attributed to a rapid internal conversion from the (π,π*) state to the lowest (π,σ*) state from which the pathway to the transition state for HCl elimination is opened in ground electronic manifolds.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.449403
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