POTENTIAL AND KINETIC ELECTRON-EMISSION FROM CLEAN GOLD INDUCED BY MULTICHARGED NITROGEN-IONS

Total electron yields have been determined from electron emission stat istics measured for impact of N4+, N5+ and N6+ under normal incidence on clean polycrystalline gold. The projectile velocities were varied f rom 2 X 10(4) m/s, where potential emission (PE) is the exclusive elec tron emitting mechanism, over the threshold for kinetic emission (KE) at about (2-3) X 10(5) m/s, up to 10(6) m/s, where KE has become the d ominant contribution. Separation of the respective PE- and KE contribu tions led to two remarkable results. (i) Comparison with measurements for inclined ion incidence from Hughes et al. (Phys. Rev. Lett. 71 (19 93) 291) suggests that the resulting PE yields not only depend on the given ''vertical impact velocity'', presumably due to different condit ions for the subsurface part of PE. (ii) The KE yields increase the st ronger with impact velocity the lower the primary ion charge, which is explained from a similar projectile charge dependence of the leading electron production mechanism for the KE process.