Secondary-ion emission from vanadium as a function of incident ion mass and energy in the range25–275keV

Measurements of the intensities of low-energy secondary ions emitted from clean and oxidized polycrystalline vanadium surfaces under (25–275)-keV ${\mathrm{He}}^{+}$, ${\mathrm{Ne}}^{+}$, ${\mathrm{Ar}}^{+}$, and ${\mathrm{Kr}}^{+}$ bombardment are reported. Whereas the intensities of the metallic-ion species are observed to be proportional to the sputtering yield of vanadium and, therefore, dependent on elastic energy deposition, the intensities of ${\mathrm{O}}^{+}$ ions are not. Rather, they increase linearly with increasing projectile velocity in a manner similar to the electronic stopping power or, equivalently, to the yield of secondary electrons. While the production of metallic ions may be described adequately by a number of the proposed models of secondary-ion emission, that of ${\mathrm{O}}^{+}$ cannot. The possibility that ${\mathrm{O}}^{+}$ is produced by a mechanism similar to electron-stimulated desorption is discussed.