ZBL Potential Research Articles

Scattering potential investigation in highly charged ion-surface interactions

We present measurements of the variation of the scattered ion yield from 10 keV and 16 keV N 6+ ions and 10 keV N 4+ ions scattered along the [1 1 0] direction of a single crystal Al(110) surface, depending on the angle of incidence. The reflected N 1+ ions were detected under θ = 35° relative to the incoming beam. The radius of the shadowcone formed behind a target atom and thus the variation of the scattered ion yield depends on the interaction potential. Monte Carlo simulations were performed to simulate the particle flux at the shadowcone edge and the scattered ion yield depending on the angle of incidence. From a comparison with the experimental data, information on the scattering potential is deduced. The experimental results can be reproduced using the ZBL potential with significantly smaller, charge state dependent screening lengths.

Giant focusing peak and potential dependence observed in a transition from axial to planar channeling in Si

A detailed study has been made of energy spectra of 1 MeV He ions, scattered elastically under grazing exit conditions, in silicon at a temperature of 164 K. The spectra, measured during an angular scan through the <110> axis, in a (211) plane, show a very rich structure. Most notable is a very strong focusing peak with a height of 2.5 times the random level, that occurs at a tilt angle of 1° with the <110> axis. The shape and the intensity of each of the spectra were compared with simulations, using two independently developed Monte Carlo simulation programs. The analysis showed that details of the spectra are quite sensitive to the assumed ion—atom potential. Major discrepancies occur when the ZBL potential is used. A considerable improvement is obtained by the use of a Hartree—Fock potential. A few other models of the ion—atom potential were also tried, and the results compared.

Simulation analysis of ion channeling spectra: thermal vibrational amplitude in Si

Abstract Energy spectra for 1 MeV He ions scattered by a Si single crystal over an angle of 58° were measured for incident directions along the 〈110〉 string and a number of directions 4° off the string: {100}, {110} and {111} planes as well as three non-channeling directions. The measurements were performed at a temperature of 164 K, under glancing-exit-angle conditions. The experimental spectra were reproduced by Monte Carlo simulation, and a x 2 analysis procedure was developed to determine the thermal vibrational amplitude in Si. Two ion-atom potentials used in the calculations (the ZBL potential and a Hartree-Fock potential) yielded essentially the same amplitude of 0.066(2) A. The corresponding Debye temperature of 490(15) K agrees well with recent determinations by other methods.