Synthesis of Cl2 induced by low energy (0–18 eV) electron impact to condensed 1,2-C2F4Cl2 molecules

Abstract

The interaction of low energy electrons (0–18 eV) with C₂F₄Cl₂ molecules condensed in multilayer amounts on a cryogenically cooled Au substrate generates Cl₂, as can be seen from the energy and temperature dependence of the Cl⁻ desorption signal. The cross section for Cl₂ formation exhibits two pronounced resonant features with maxima near 0 and 10 eV, dropping to essentially zero in the energy range between the resonances (near 3 eV). The energy dependence of the reaction cross section qualitatively follows that of Cl⁻ desorption, which itself can be correlated to dissociative electron attachment (DA) processes in the gas phase. While at 10 eV excited negative ion resonances and electronically excited states of neutral C₂F₄Cl₂ may be involved in the process, in the low energy region (<2 eV) the reaction can only be initiated by dissociative electron attachment. Possible reaction pathways are discussed.