Interactions of fast C₂₀clusters with solids: Coulomb explosions, charge states and energy losses

Abstract

The dielectric response formalism is used to evaluate the dynamically screened interaction potential among the ions in a fast C20 cluster passing through a solid target. This potential is further used to calculate the individual ion charge states in the cluster by means of a statistical–variational theory which takes into account the effects of the vicinity of the neighbouring ions. Coulomb explosion and the energy losses of the cluster are simulated by solving equations of motion for individual ions while taking into account, in a self-consistent manner, the variation of ion charges in the course of explosion. Moreover, a Monte Carlo method is used to simulate the effects of multiple scattering of cluster constituent ions on target atoms. It is found that, owing to the wake-like asymmetry of the inter-ionic potential, both the distribution of ion charges in the cluster and the Coulomb explosion patterns exhibit strong spatial asymmetries in the direction of motion. It is also shown that the cluster energy losses exhibit characteristic interferences due to the vicinity effects, which diminish after long dwell times.

Origin of nonlinear sputtering during nanocluster bombardment of metals

“…The droplet model shows that at least the main features of the cascade development can be explained without considering special coherent interactions of the cluster atoms when they move through the material or coherent effects such as Coulomb explosion in the cascade. [31][32][33][34] In the interaction model used in the simulations, the attractive interatomic forces depend solely on the approximated electronic density induced by the neighbor atoms without any excitations or electronic correlation effects. The short distance repulsive forces are calculated using the ZBL approximation, 14 which describes single ion collisions with a target.…”

“…Interactions between closely moving cluster atoms, known as vicinage effects, introduce even more complicated interactions than the sheltering effect, and these effects are under discussion. 34,[36][37][38] The droplet model is based on several approximations which are valid in target elements similar to gold. In many respects, the model is very general and we suppose it is valid for all dense materials, which do not have structure that distorts collision cascades spatially.…”

Coulomb Explosion and Energy Loss of Energetic C 20 Clusters in Dense Plasmas

“…Coulomb explosion is an interesting phenomenon for fast clusters travelling in plasmas, especially for larger clusters such as C 20 . In solids, the coulomb explosions of C 20 clusters have been reported in an Al target [8] and oxides (Al 2 O 3 , SiO 2 ). [9] For molecular ions in plasma targets, we have studied H 2 , N 2 and C 60 clusters, [10−12] the results show that the explosion patterns exhibit strong asymmetries due to the wake effect after long penetration times.…”