Formation of translationally hot ethene by dissociative electron capture of adsorbed 1,2-dichloroethane

Irradiation of sub-monolayer and 4 layers of adsorbed 1,2-dichloroethane (DCE) on Cu(111) at 110 K with a pulsed 2 keV electron beam causes hot ethene desorption with translational temperatures of 2350 ± 100 K (sub-monolayer), and 2540 ± 200 K and 320 ± 50 K (4 layers). DCE undergoes electron attachment from hot secondary electrons, dissociating to form a short-lived ClCH2CH2 radical which decomposes, generating the high temperature (2350 and 2540 K) ethene. The translational motion is thought to come from part of the heat liberated in the formation of the CuCl bond. The 320 K peak is assumed to arise from radical decomposition at the surface of DCE crystallites.