Study of the secondary negative ion emission of copper and several of its alloys by impact with Cs+ ions

Secondary ion emission studies have been undertaken using Cs+ as the primary ion beam. A good vacuum (ca. 10-8 torr) is needed to eliminate contamination by residual gases. Negative ion emission of pure copper is compared with its alloys. The thermodynamic equilibrium model of Andersen is discussed. For low element concentrations, the experimental data show enhancement in negative emission of P, Al, Fe, Sn, Ni, and attenuation for Zn, Pb. The order of magnitude of ionic efficiency S- for copper is evaluated at 10-4. (Auth.)