A theoretical model is developed to study the energy loss of heavy ions specularly reflected on a solid surface at a glancing angle using the dielectric response theory and the specular reflection model. A local-field correction and a plasmon-pole approximation for dielectric function are employed in the low- and highvelocity regimes, respectively. Also, the Brandt-Kitagawa model is used to express the distribution of the electrons bound to the projectiles. We obtain analytical expressions for the position-dependent stopping power and the surface image potential. The energy losses, dependent on the charge state of the ions and the incident angles, are calculated and compared with the corresponding experimental results.

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 theorywhich 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 ofmotion 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 ofmultiple 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. (Some figures in this article are in colour only in the electronic version)

A hydrodynamic model is established to study the interactions of a dust particle with a radio-frequency (rf) sheath, taking into account the influence of the spatial inhomogeneity of the ~rf! sheath, as well as the influence of the ion-neutral collisions. Numerical results are obtained for the charge on the dust particle and for the spatial distribution of the induced potential around this particle, based on a self-consistent modeling of the sheath parameters such as the sheath electric field, the ion velocity, and the ion and electron densities. The induced potential exhibits the familiar oscillatory structure of a wake potential, which is, however, strongly damped due to the collisional effects. The spatial inhomogeneity of the rf sheath gives rise to a further damping of the induced potential, as well as to a reduction of the oscillations at large distances from the dust particle.

A hybrid theoretical model, capable of describing the characteristics of a collisional sheath driven by a sinusoidal current source and determining the energy and angular distributions of ions incident onto the substrate, is proposed. The model consists of one-dimensional time-dependent fluid equations coupled with the Poisson equation determining spatiotemporal evolution of the sheath and the Monte Carlo simulation predicting the energy and angular distributions of ions striking the electrode, in which charge-exchange collisions between ions and neutrals are included. Additionally, an equivalent circuit model in conjunction with the fluid equations is adopted to self-consistently determine the relationship between the instantaneous potential at a rf-biased electrode and the sheath thickness. It is found that the collisional effects would influence the height of the energy peaks in the ion energy distributions and the ion angular distributions.

A self-consistent fluid model is proposed for describing collisionless radio-frequency ~rf! sheaths driven by a sinusoidal current source. This model includes all time-dependent terms in ion fluid equations, which are commonly ignored in some analytical models and numerical simulations. Moreover, an equivalent circuit model is introduced to determine self-consistently the relationship between the instantaneous potential at a rf-biased electrode and the sheath thickness. The time-dependent voltage wave form, the sheath thickness and the ion flux at the electrode as well as the spatiotemporal variations of the potential, the electric field and the ion density inside the sheath are calculated for various rf powers and ratios of the rf frequency to the ion plasma frequency. The ion energy distributions ~ IEDs! impinging on the rf-biased electrode are also calculated with the ion flux at the electrode. The numerical results show that the frequency ratio is a crucial parameter determining the spatiotemporal variations of the rf sheath and the shape of the IEDs.