Multistep cascade model for the deexcitation of highly charged ions impinging on a solid surface.

Abstract

We introduce a multistep cascade model for the deexcitation of highly charged ions in the presence of a solid. We apply this model to analyze the yield of the KLL-Auger peak as measured in angular resolved electron energy spectra. The calculation makes use of three probability densities, one for the time distribution of the Auger decay, one for the transport of the ions through the first atomic layers of the target, and the last one for the transport of the electrons from the source to the detector. Each of these probabilities is discussed and modeled. The calculations are compared to measurements of KLL-Auger electrons from low-energy ${\mathrm{Ne}}^{9+}$ ions impinging on solid Al. The results support previous estimations that the L-shell sidefeeding of the projectile depends on the incident velocity. For ion energies greater than 1000 eV, the mean path length needed to capture an electron is found to be approximately equal to the next-neighbor distance in the Al lattice. We estimate the yield of KLL electrons emitted from Ne ions with 2,3,...,8 electrons in the L shell. The mean depth of emission of the KLL electron is determined.