Auger-electron emission from slow, highly charged ions interacting with solid Cu targets

Secondary-electron energy spectra were measured for ${\mathrm{Ar}}^{\mathit{q}+}$ (q=9 and 16) and the H-like ions ${\mathrm{N}}^{6+}$, ${\mathrm{O}}^{7+}$, and ${\mathrm{Ne}}^{9+}$, incident on solid Cu surfaces at an angle of 10°. The impact energy was varied from 10q to 20q keV. Auger electrons were detected at various observation angles from 20° to 180° with respect to the incident beam. From the Doppler shift of the projectile Auger electrons, the L Auger electrons of argon and neon are found to be emitted from ions whose flight direction is parallel to the incident beam and the K Auger electrons of nitrogen, oxygen, and neon are observed to be emitted from deflected ions. Evidence is provided for incident ${\mathrm{Ne}}^{9+}$ and ${\mathrm{Ar}}^{16+}$ that the L shells are incompletely filled when the projectiles reach the surface. The data analysis is supported by model calculations.