Proton backscattering

Fig. 12. Angular distribution of protons backscattered from polycrystalline Nb target into different energy ranges74)...

Particle- or proton-induced. X-ray emission (PIXE) is another modern powerful yet non-destructive elemental analysis technique used to determine the elemental make-up of a sample material. When a material is exposed to a particle or proton beam, atomic interactions occur that give off electromagnetic radiation of wavelengths in the X-ray part of the electromagnetic spectrum characteristic of an element. Three different types of spectra can be collected from a PIXE experiment an X-ray emission spectrum, a Rutherford (proton) backscattering spectrum and a proton transmission spectrum. 

XPS only gives information on the cationic Ce species. To obtain information on the anion species, as seen above, vibrational techniques can be used but for this particular experiment they did not provide much information on the reaction with the surface. This may in part be due to the thicker oxides that were on the surface that may have obscured the anionic inhibitor phase. In this instance, Rutherford back-scattering spectroscopy (RBS) was used. RBS is a nuclear technique which relies on measuring the energy of either a-particles or protons backscattered from nuclei in the sample. This higher atomic number species will generally have greater sensitivity. 

Within the last 5—10 years PIXE, using protons and helium ions, has matured into a well-developed analysis technique with a variety of modes of operation. PIXE can provide quantitative, nondestructive, and fast analysis of essentially all elements. It is an ideal complement to other techniques (e.g., Rutherford backscattering) that are based on the spectroscopy of particles emitted during the interaction of MeV ion beams with the surface regions of materials, because... 

Figure 4 Angular distribution of backscattered protons from clean and S-covered...

Figure 4 Spectrum of diffusion in the mineral olivine ((Mg, Fe)2 SiO ) taken using nonresonant profiling technique with the reaction (p, a) Both the a particles resulting from the nuclear reaction and backscattered protons are collected. Inset shows expanded region of the spectrum, where a yield indicates diffusion of into the material.

The use of nuclear techniques allows the determination of C, N, H, O, and heavier contaminants relative fractions with great accuracy, and of the elements depth profile with moderate resolution (typically 10 nm). Rutherford backscattering spectroscopy (RBS) of light ions (like alpha particles) is used for the determination of carbon and heavier elements. Hydrogen contents are measured by forward scattering of protons by incident alpha particles (ERDA) elastic recoil detection analysis [44,47]. 

Ion beam probes are used in a wide range of techniques, including Secondary Ion Mass Spectroscopy (SIMS), Rutherford backscattering spectroscopy (RBS) and proton-induced X-ray emission (PIXE). The applications of these and number of other uses of ion beam probes are discussed. 

Figure 13.4. Energy distribution of backscattered protons from a glass substrate after immersion in a PdCl2 bath and subsequent deposition of a thin carbon layer. Contributions due to the backscatter yield from different species are indicated. (From Ref. 2, with permission from the Electrochemical Society.)...

Figure 13.4 illustrates the energy distribution of backscattered protons off a glass substrate after immersion in PdCl2 bath. The various atomic species present are indicated. 

The neutron backscatter technique is best performed with hydrogen-containing products. Both the source of a slow neutron and the receiver are located in the same box. The slow neutrons bounce off of protons (hydrogen ions) and are reflected back. The rate at which these neutrons are reflected back is measured, and corresponds to the hydrocarbon density in the vessel. This measurement is not affected by steel components inside—or outside—the vessel. 

If the thin-film or surface target consists of two or more atomic species, the energy distribution function of the backscattered protons shows some structure. The... 

Pt-Re Coimpregnated on A1203./ - / sulfided Proton induced X-ray emission, Rutherford backscattering, electron microscopy. 

X-ray photoelectron spectroscopy (XPS), SIMS (Secondary Ion Mass Spectroscopy) and nuclear-reaction-based analyses (like RBS - Rutherford Backscattering -, and PIXE - Proton Induced X-ray Emission) have already proven their complementary potentialities. 

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