Complete chemical transformation of a molecular film by subexcitation electrons (<3 eV) -: art. no. 213201

The potential of slow electrons to act as a soft tool to control a chemical reaction in the condensed phase is demonstrated. By setting the energy of a well defined electron beam to values below 3 eV, the surface of a thin film of 1,2-C2F4Cl2 molecules can completely be transformed into molecular chlorine (and by-products, possibly perfluorinated polymers). At higher energies (>6 eV) some equilibrium state between product and educt composition can be achieved, however, accompanied by a gradual overall degradation of the film. The effect of complete transformation is based on both the selectivity and particular energy dependence of the initial step of the reaction which is dissociative electron attachment to C2F4Cl2, but also the fact that the initial molecule is efficiently decomposed by subexcitation electrons while the product Cl-2 is virtually unaffected.