Classical Dynamics Calculations Research Articles

Preferential sputtering of binary compounds: A model study

A model classical dynamics calculation has been performed to ascertain the effect of atomic mass and surface binding energy on preferential sputtering in binary systems. We find the mass effect not to have a simple dependence on the ratio of the masses of the two components. Rather, for two binary systems, both with a mass ratio of ~ 3, the ejection yield of the lighter component can vary from being the same as that of the heavier component to being 100% larger. Over a limited range of surface binding energies the ejection yield is inversely proportional to the binding energy. In addition, we suggest that the effective scattering sizes should be considered as a possible cause for preferential sputtering.

A study of the friction force dependence of the heavy-ion fusion cross sections

A systematic study of the dependence of fusion cross sections on the strength of the friction force has been performed by carrying out classical dynamical trajectory calculations for a number of heavy-ion target-projectile systems. On comparing the calculations with the available experimental data on fusion excitation functions for few typical light-heavy-ion systems, it was seen that in the high-energy region, where the fusion cross sections depend sensitively on the strength of the friction force, there appears to be a trend in the data, that is not easily explained by a simple linear velocity-dependent friction force. However, even in this region, the paucity of experimental data prevents one from drawing any definite conclusions.

Azimuthal Anisotropies of Dimer Ions Ejected from Ion Bombarded Ni(001)

The angular distributions of ${\mathrm{Ni}}^{+}$ and ${\mathrm{Ni}}_{2}^{+}$ ejected from Ni(001) by bombardment with 2-keV ${\mathrm{Ar}}^{+}$ have been shown to exhibit large azimuthal anisotropies. The experimental results have been well reproduced by classical dynamical calculations of the ion impact event. For the dimers, the peak in the distribution arises from a unique ejection mechanism such that the atoms in the dimer are known to form from specific surface locations relative to the ion impact position.

Evidence for a recombination mechanism of cluster emission from ion bombarded metal surfaces

Abstract Classical dynamical calculations of the momentum dissipation of 600–20 000 eV Ar + in clean metal single crystals indicate that the experimentally observed cluster species form by a recombination mechanism in the near surface region. The dependence of cluster yields on primary ion energy has been computed and matches well the shape of the experimental curve for Ni 3 + /Ni 2 + . The results suggest that a simple power law based on the yield of monomers is not sufficient to predict accurate cluster yields.