LOW-ENERGY ELECTRON DRIVEN PROCESSES IN ICES: SYNTHESIS REACTIONS AND SURFACE FUNCTIONALIZATION

Low-energy electrons, and subexcitation energy electrons in particular, have the ability to induce efficiently chemical modifications within condensed molecular films and at substrate surfaces. By taking advantage of the Dissociative Electron Attachment (DEA) process, which leads to selective bond cleavages, the induced reactivity can be controlled solely by the electron energy. Two illustrative examples of induced reactivity and substrate functionalization achieved by low-energy electron processing of condensed molecules studied by means of High Resolution Electron Energy Loss Spectroscopy (HREELS) are reviewed, and special interest is given to the possibility of proposing overall reaction mechanisms. The resonant decarboxylation reaction in condensed films of trifluoroacetic acid CF3COOH induced by electrons at ~1 eV involves the formation of the transient species (CF3COOH) # - and the further formation of CO2 by a concerted mechanism. Diamond substrate functionalization by CH2CN organic groups through Cdiam—C and Cdiam—N bonds is performed by 2 eV electron irradiation of condensed acetonitrile CH3CN and involves reactants formed by DEA, that are neutral radicals Hand molecular anions (H2CCN) - .