Recoil ion

The energy of scattered or recoiled ions can be measured directly by means of an electrostatic energy analyser. If the TOF method is used, the relation between scattering energy E and TOF is expressed as... 

Shoji F, Kashihara K, Sumitomo K and Oura K 1991 Low-energy recoil-ion spectroscopy studies of hydrogen adsorption on Si(100)-2 x i surfaces Surf. Sc/. 242 422-7... 

A depth scale can be obtained from the energy of recoiled ions. If ions recoiled from a depth x are lower in energy by AE compared with ions recoiled from the surface, a simple relationship between AE and x can be found for thin layers, when constant stopping power is assumed ... 

As a second example, results from a TOP ERDA measurement for a multi-element sample are shown in Fig. 3.65 [3.171]. The sample consists of different metal-metal oxide layers on a boron silicate glass. The projectiles are 120-MeV Kr ions. It can be seen that many different recoil ions can be separated from the most intense line, produced by the scattered projectiles. Figure 3.66 shows the energy spectra for O and Al recoils calculated from the measured TOF spectra, together with simulated spectra using the SIMNRA code. The concentration and thickness of the O and Al layers are obtained from the simulations. 

The main experimental techniques used to study the failure processes at the scale of a chain have involved the use of deuterated polymers, particularly copolymers, at the interface and the measurement of the amounts of the deuterated copolymers at each of the fracture surfaces. The presence and quantity of the deuterated copolymer has typically been measured using forward recoil ion scattering (FRES) or secondary ion mass spectroscopy (SIMS). The technique was originally used in a study of the effects of placing polystyrene-polymethyl methacrylate (PS-PMMA) block copolymers of total molecular weight of 200,000 Da at an interface between polyphenylene ether (PPE or PPO) and PMMA copolymers [1]. The PS block is miscible in the PPE. The use of copolymers where just the PS block was deuterated and copolymers where just the PMMA block was deuterated showed that, when the interface was fractured, the copolymer molecules all broke close to their junction points The basic idea of this technique is shown in Fig, I. 

The surface structures of ionic liquids have been studied by direct recoil spectrometry. In this experiment, a pulsed beam of 2-3 keV inert gas ions is scattered from a liquid surface, and the energies and intensities of the scattered and sputtered (recoiled) ions are measured as a function of the incident angle, a, of the ions. Figure 4.1-16 shows a scheme of the process for both the scattered and sputtered ions. 

In the past few years there has been a very intense effort to understand the process of single ionization in ion-atom collisions. Experiments in this area have followed largely along three main paths recoil-ion momentum spectroscopy... 

In Section III we discuss the applicability of these models for kinematically complete experiments on target single ionization in ion-atom collisions, which have been performed using the technique of recoil-ion momentum spectroscopy. The examples illustrated will include the pioneering experiments [2,4,5] of... 

In this section we consider the final-state longitudinal momentum distributions of the ejected electron, recoil-ion, and projectile momentum transfer in the single... 

Normally these conditions are satisfied in fast highly charged ion-atom collisions. From Eq. (66) we can derive the equations for the singly differential cross sections with respect to the components of the longitudinal momentum distributions for the electron, recoil-ion, and projectile. The longitudinal electron momentum distribution da/dpe for a particular value of p, may be derived by integrating over the doubly differential cross section with respect to the electron energy Ek ... 

Figure 2. Same as Fig. 1 but for the longitudinal momentum distribution of the recoil ion. 

Figure 8. Longitudinal momentum distribution for single ionization of helium by 945-keV antiproton (data points) in comparison with proton collision (full curve), (a) Electron momentum data [26] (b) recoil-ion data [26], The theoretical calculations represent antiproton collisions dotted curve, CDW results [26] broken curve, CTMC result [26], Here pze and pzr are equivalent to the notation of pey and pRy of Figs. 1 and 2, respectively.

After several decades of systematic electron spectroscopy in ion-atom collisions by many groups (for recent reviews see Refs. 13 and 51), there are only two data sets of doubly differential experimental cross sections cfa/dE dfl for the emission of electrons with < 1 eV. It has been only recently that, with entirely new and extremely efficient electron spectrometers combined with recoil-ion momentum spectroscopy [52], doubly differential cross sections for ultralow -and low-energy electrons (1.5 meV < < 100 eV) have been obtained by... 

Figure 14. Double differential cross sections (ddcs — 2n dv v J for electron emission due to single, double, or triple ionization of Ar by 3.6-MeV/amu Au53+ ions. The DDCS for the specified recoil-ion charge states are added according to their relative contribution to the total cross section. CDW-EIS results (solid lines [73]) are shown along with the experimental data from Moshammer et at. [53], The experimental data are divided by 1.4. Cross sections at different ve are multiplied by factors of 10, respectively.

This review illustrates the complementary nature of recoil-ion momentum spectroscopy, projectile scattering measurements, and conventional electron emission spectroscopy in ion-atom ionizing collisions. We have examined recent applications of both the CDW and CDW-EIS approximations from this perspective. We have shown that both models provide a flexible and quite accurate theory of ionization in ion-atom collisions at intermediate and high energies and also allows simple physical analysis of the ionization process from the perspective of these different experimental techniques. 

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