Rutherford Backscattering RBS

Rutherford scattering is an elastic event, that is, no excitation of either the projectile or target nuclei occurs. However, due to conservation of energy and momentum in the interaction, the kinetic energy of the backscattered ion is less than that of the incident ion. The relation between these energies is the kinematic factor, K, which is given by the expression 

A geometry that allows detection of the scattered ct particles at very large angles is usually selected. 

The probability or cross section for Rutherford scattering (Chapter 10) is given (Segre, 1977) as  

Another important application of this technique has been to determine the elemental composition of the lunar and Martian surfaces. Turkevich et al. (1969) constructed a rugged device to measure the backscattering of a particles from the lunar surface, which flew on three Surveyor missions in 1967-68 and yielded the first complete and accurate analysis of the lunar surface. The a particles came from a radioactive source (242Cm) that was part of the instrument package. The results of these experiments, which showed an unexpected and comparatively high abundance of Ti, were confirmed by laboratory analysis of lunar samples gathered in the Apollo missions. Since then, this technique has been used to study Martian rocks and soil. 

For each of the following analyses, indicate what role, if any, activation analysis could or should play. Be sure to clearly state the reasons for your choice. 

---

Rutherford Backscattering (RBS) provides quantitative, nondestructive elemental depth profiles with depth resolutions sufficient to satisfy many requirements however, it is generally restricted to the analysis of elements heavier than those in the substrate. The major reason for considering depth profiling using FIXE is to remove this restrictive condition and provide quantitative, nondestructive depth profiles for all elements yielding detectable characteristic X rays (i.e.,Z> 5 for Si(Li) detectors). 

SALI compares fiivorably with other major surface analytical techniques in terms of sensitivity and spatial resolution. Its major advantj e is the combination of analytical versatility, ease of quantification, and sensitivity. Table 1 compares the analytical characteristics of SALI to four major surfiice spectroscopic techniques.These techniques can also be categorized by the chemical information they provide. Both SALI and SIMS (static mode only) can provide molecular fingerprint information via mass spectra that give mass peaks corresponding to structural units of the molecule, while XPS provides only short-range chemical information. XPS and static SIMS are often used to complement each other since XPS chemical speciation information is semiquantitative however, SALI molecular information can potentially be quantified direedy without correlation with another surface spectroscopic technique. AES and Rutherford Backscattering (RBS) provide primarily elemental information, and therefore yield litde structural informadon. The common detection limit refers to the sensitivity for nearly all elements that these techniques enjoy. 

As NRA is sensitive only to the nuclei present in the sample, it does not provide information on chemical bonding or microscopic structure. Hence, it is often used in conjunction with other techniques that do provide such information, such as ESCA, optical absorption. Auger, or electron microscopy. As NRA is used to detect mainly light nuclei, it complements another accelerator-based ion-beam technique, Rutherford backscattering (RBS), which is more sensitive to heavy nuclei than to light nuclei. 

Rutherford backscattering (RBS) He 4He 30 nm heavy atoms jim — movement of markers... 

Secondary Ion Mass Spectrometry (SIMS) Secondary Neutral Mass Spectrometry (SNMS) Rutherford Backscattering (RBS)... 

In addition to the techniques already discussed, aspects of MC formation in LB films have been investigated by Rutherford backscattering (RBS) (65) and fluorimetry (17,49,50.76,79,81,83,84). The results from the RBS analysis of H2S-exposed CdAr films provided evidence for the formation of spheroidal CdS particles. Investigations of the fluorescence properties of MC particles in LB films are discussed later. 

Blends of this copolymer with polystyrene were analysed by contact angle measurements and Rutherford backscattering (RBS) both of which showed that the surface was silicone rich. 

Techniques based on the interaction of ions with solids, such as secondary ion mass spectrometry (SIMS) and low-energy ion scattering (LEIS) have undoubtedly been accepted in catalyst characterization, but are by no means as widely applied as for example X-ray photoelectron spectroscopy (XPS) or X-ray diffraction (XRD). Nevertheless, SIMS, with its unsurpassed sensitivity for many elements, may yield unique information on whether or not elements on a surface are in contact with each other. LEIS is a surface technique with true outer layer sensitivity, and is highly useful for determining to what extent a support is covered by the catalytic material. Rutherford backscattering (RBS) is less suitable for studying catalysts, but is indispensable for determining concentrations in model systems, where the catalytically active material is present in monolayer (ML)-like quantities on the surface of a flat model support. 

Fig. 4.14 Schematic representation of Rutherford backscattering (RBS). (a) The incident ions are directed such that they either scatter back from surface atoms or channel deeply into the crystal, (b) The ions scatter back from target atoms throughout the outer micrometers and suffer inelastic losses, causing the energy of the backscattered ions to tail to zero, (c) Scattering from the heavy outer layer gives a sharp peak separated from the spectrum of the substrate as in (b).

Fig. 9.28 Rutherford backscattering (RBS) proves that chromate can indeed desorb from the model catalyst during thermal activation. A wafer with 10 Cr nm 2 loading features 7.0 Cr nm-2 after calcination at 550 °C. The desorbing chromate readily re-adsorbs on an empty silica surface placed opposite to the loaded wafer. (Adapted from [99]).

In situ methods permit the examination of the surface in its electrolytic environment with application of the electrode potential of choice. Usually they are favored for the study of surface layers. Spectroscopic methods working in the ultra high vacuum (UHV) are a valuable alternative. Their detailed information about the chemical composition of surface films makes them an almost inevitable tool for electrochemical research and corrosion studies. Methods like X-ray Photoelectron Spectroscopy (XPS), UV Photoelectron Spectroscopy (UPS), Auger Electron Spectroscopy (AES) and the Ion Spectroscopies as Ion Scattering Spectroscopy (ISS) and Rutherford Backscattering (RBS) have been applied to metal surfaces to study corrosion and passivity. 

On top of the newly developed supports a steam-stable intermediate layer was coated. The preparation of these layers is treated in detail in chapter 5. After this, the permselective silica layer was applied, which should be resistant against high temperature and steam-containing environments as well. The experimental procedure together with some transport and Rutherford BackScattering (RBS) studies are described in chapter 6. 

In this study modified silica layers were applied on undoped, flat Y-AI2O3 membranes, as described in chapter 5. Rutherford Backscattering (RBS) on some selected doped membranes was used to reveal the location of the dopants in the membrane structure. 

Rutherford backscattering RBS Similar to ISS, except the main focus is on depth profiling and Composition... 

Figure 7.40. Rutherford backscattering (RBS) spectrum of a LiNiV04 film (thickness of 240( 5) A) on a carbon substrate. The open squares represent the experimental RBS data, and the continuous fine is the simulated data. Reproduced with permission from Reddy, M. V. Pecquenard, B. Vinatier, R Levasseur, A. J. Phys. Chem. B 2006,110,4301. Copyright 2006 American Chemical Society.

Miscellaneous other UHV methods are of minor importance only. Norton et al. (54) attempted to monitor the hex 1 x 1 phase transition of Pt(lOO) during CO/O2 oscillations by Rutherford backscattering (RBS), but the results were not very conclusive. RBS, however, might reveal information about the faceting of the Pt(llO) surface during the course of oscillations. Some other UHV methods, such as XPS, have also been applied to obtain the steady-state information necessary for the interpretation of oscillatory results (69). 

Thin films of Cu, Co and Ni on Si were prepared from different aqueous electrolytes containing sulfates of the respective metals as well as some supporting electrolyte/additive. Voltammetry and current transients were used to analyze the electrochemical aspects of the deposition. The electrodeposited layers were investigated by scanning electron microscopy (SEM), Rutherford backscattering (RBS), magnetooptical Kerr effect (MOKE), X-ray diffractometry (XRD) as well as by electrical measurements. 

Surface Analysis Attenuated Total Internal Reflectance (ATIR), EDX, Rutherford Backscattering (RBS), Electron Spectroscopy for Chemical Analysis (ESCA) also known as X-ray Photoelectron Spectroscopy (XPS), Secondary Ion Mass Spectrometry (SIMS), Ion Scattering Spectroscopy (ISS)... 

---