Formation of HCN+ in Heterogeneous Reactions of N2+ and N+ with Surface Hydrocarbons

A significant increase of the ion yield at m/z 27 in collisions of low-energy ions of N2(+) and N(+) with hydrocarbon-covered room-temperature or heated surfaces of tungsten, carbon-fiber composite, and beryllium, not observed in analogous collisions of Ar(+), is ascribed to the formation of HCN(+) in heterogeneous reactions between N2(+) or N(+) and surface hydrocarbons. The formation of HCN(+) in the reaction with N(+) indicated an exothermic reaction with no activation barrier, likely to occur even at very low collision energies. In the reaction with N2(+), the formation of HCN(+) was observed to a different degree on these room-temperature and heated (150 and 300 °C) surfaces at incident energies above about 50 eV. This finding suggested an activation barrier or reaction endothermicity of the heterogeneous reaction of about 3-3.5 eV. The main process in N2(+) or N(+) interaction with the surfaces is ion neutralization; the probability of forming the reaction product HCN(+) was very roughly estimated for both N2(+) and N(+) ions to about one in 10(4) collisions with the surfaces.