MULTISTEP CASCADE MODEL FOR THE DEEXCITATION OF HIGHLY-CHARGED IONS IMPINGING ON A SOLID-SURFACE

We introduce a multistep cascade model for the deexcitation of highly charged ions in the presence of a solid. We apply this model to analyz e the yield of the KLL-Auger peak as measured in angular resolved elec tron energy spectra. The calculation makes use of three probability de nsities, 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. T he calculations are compared to measurements of KLL-Auger electrons fr om low-energy Ne9+ ions impinging on solid Al. The results support pre vious estimations that the L-shell sidefeeding of the projectile depen ds on the incident velocity. For ion energies greater than 1000 eV, th e mean path length needed to capture an electron is found to be approx imately equal to the next-neighbor distance in the Al lattice. We esti mate the yield of KLL electrons emitted from Ne ions with 2, 3,...,8 e lectrons in the L shell. The mean depth of emission of the KLL electro n is determined.