Ion-solid interactions

Interactions among atoms, ions, and solid surfaces are not limited only to those in SIMS. They are also noted and even used in other analytical techniques with examples including  

Metastable De-excitation Spectroscopy (MDS), also known as Penning Ionization Electron Spectroscopy (PIES) and Metastable Quenching Spectroscopy (MQS) 

These are of interest as they simplify the ionization/neutralization processes active on an ion, atom, and/or molecule in close proximity to a solid s surface, by removing the sputtering event. In the case of LEIS, a low-energy ion beam is directed at a solid s surface such that electron interaction (that resulting in 

In these cases, the type and probability of the electron interaction taking place may depend on  

the interaction time as defined by the scattered atom/ion angle of incidence and velocity, 

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M. Nastasi, J. W. Mayer, and. K. Hirvonen, Ion Solid Interactions Fundamentals and Applications, Cambridge University Press, Cambridge, in press. 

Nevertheless, one has to keep in mind that during the complicated processes of the ion-solid interaction mixing or even ion bombardment induced chemical reactions may occur between the components of the islands and the substrate. In general, events following the impact of... 

The defects generated in ion—solid interactions influence the kinetic processes that occur both inside and outside the cascade volume. At times long after the cascade lifetime (t > 10-11 s), the remaining vacancy—interstitial pairs can contribute to atomic diffusion processes. This process, commonly called radiation enhanced diffusion (RED), can be described by rate equations and an analytical approach (27). Within the cascade itself, under conditions of high defect densities, local energy depositions exceed 1 eV/atom and local kinetic processes can be described on the basis of a liquid-like diffusion formalism (28,29). 

Simulations. In addition to analytical approaches to describe ion—solid interactions two different types of computer simulations are used Monte Carlo (MC) and molecular dynamics (MD). The Monte Carlo method relies on a binary collision model and molecular dynamics solves the many-body problem of Newtonian mechanics for many interacting particles. As the name Monte Carlo suggests, the results require averaging over many simulated particle trajectories. A review of the computer simulation of ion—solid interactions has been provided (43). 

The primary requirement for carrying out MD simulations is a suitable interatomic potential for the description of forces acting between atoms in the cascade. A general discussion on MD can be found (47) and detailed summaries of the use of MD in ion—solid interactions are also available (43,48). 

Ion—Solid Interactions. F. Ziegler, J. P. Biersack, and U. Littmark,17tf Stoppingand Range of Ions in Solids, Peigamon Press, Inc., New York, 1985. 

Figure 16 Representation of ion-solid interaction and sputtering process. (From Ref. 64.)...

Impregnation by Soaking, or with an Excess of Solution [2]. Excess liquid is eliminated by evaporation or by draining. Deposition of the active element is never quantitative. The quantity deposited depends on the solid/liquid ratio. Deposition is slow, requiring several hours or days. Extensive restructuring of the surface (loss of surface area, etc.) may occur. However, the method allows the distribution of the species to be very well controlled and high dispersions may be obtained. The method works best if ion/solid interactions are involved. 

Eckstein W., Computer Simulation of Ion-Solid Interactions, Vol. 10, Springers Series in Material Sciences (Springer, Berlin 1991)... 

Ion-solid Interaction Division Van de GraafT Group National Accelerator Centre P.O. Box 72... 

W. Eckstein, Computer Simulation of Ion Solid Interactions (Springer, 1991). 

Davies JA (1992) Fundamental concepts of ion-solid interactions Single ions, 10" seconds. Mater Res Soc Bull 17 26-29... 

Nastasi M, Mayer JW, Hirvonen JK (1996) Ion-Solid Interactions. Cambridge University Press, Cambridge, UK, 540 p... 

Nastasi, M. Mayer, J.W. Hirvonen, J. Ion-Solid Interactions Fundamentals and Applications Cambridge University Press UK, 1996. 

We analyze in this chapter recent developments in the area of ion-solid interactions, describing in particular the non-linear method to study the energy loss of ions in solids. We consider the non-perturbative scheme provided by quantum scattering theory, using self-consistent methods to... 

Collisions with atomic clusters represent a relatively new branch of collision physics as compared to the well established fields of ion-atom collisions [1] and ion-solid interaction [2]. The study of cluster collisions is of particular interest and importance because it offers the possibility, to tackle bridge-building questions (like the transition from individual excitations in the elementary ion-atom collision to the macroscopic stopping power in solids) as well as fundamental problems (like phase transitions in finite systems). 

In the SI (or MKS) system of units, the joule (J) is a unit of energy, but the electron-volt (eV) is the traditional unit used in ion-solid interactions we can define 1 eV as the kinetic energy gained by an electron accelerated through a potential difference of 1 V. The charge on the electron is 1.602 x 10 19 C, and a joule is a Coulomb-volt, so that the relationship between these units is given by... 

In ion-solid interactions it is convenient to use cgs units rather than SI units in relations involving the charge on the electron. The usefulness of cgs units is clear when considering the Coulomb force between two charged particles with Z, and Zq units of electronic charge separated by a distance r... 

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