Ion beam interaction with matter

Figure 1 The relationship between properties of the ion beams interacting with matter and items of ion beam applications.

In this introductory chapter, we present the types and main properties of ionizing radiation and general description of its interaction with matter. In addition, taking into account that some other chapters of the present book are dedicated, in particular, to the synthesis of materials using P-particles and y-irradiation, here in the present chapter we will carry out the analysis of examples of more rare application of a-particles, x-rays, neutrons, protons, and ion beams for obtaining various materials, composites, and chemical compounds. 

The initial obvious statement is that, overall, neutrons interact with matter even less strongly than do X-rays. Table 10.8 summarizes the differences between the two probes. For both neutrons and X-rays, it is not as easy to direct the beam as it is with electrons or ions. In both cases, the experimental method involves measuring the intensity of the scattered beam as a function of scattering angle. 

It seems relevant to remind that this technique is based on recording the backscattered light (usually helium) ions occurred as a result of their interaction with the matter of a solid layered specimen (for more detail, see Ref. 124). Experimental data are presented as plots of intensity, /, against energy, E, of the beam of backscattered ions (Fig. 2.15). 

X-rays interact with electrons in matter. When a beam of X-rays impinges on a material it is scattered in various directions by the electron clouds of the atoms. If the wavelength of the X-rays is comparable to the separation between the atoms, then interference can occur. For an ordered array of scattering centres (such as atoms or ions in a crystalline solid), this can give rise to interference maxima and minima. The wavelengths of X-rays used in X-ray diffraction experiments therefore typically lie between 0.6 and 1.9 A. 

Inner-shell vacancies can also be a result of interactions with energetic particles (electrons, protons, etc.) thus, emission of characteristic X-rays and of Auger electrons also occurs when matter is irradiated with electron, proton, or heavier ion beams. These effects are employed in various methods for elemental analysis including PIXE mentioned earlier. 

Spectrometric methods are a large group of analytical methods that arc based on atomic and molecular spectroscopy. Spectroscopy is a general term for the science that deals with the interactions of various types of radiation with matter. Historically, the interactions of interest were between electromagnetic radiation and matter, but now spectroscopy has been broadened to include interactions between matter and other forms of energy. Examples include acoustic waves and beams of particles such as ions and electrons. Spectrometry and spectrometric methods refer to the measurement of the intensity of radiation with a photoelectric transducer or other type of electronic device. 

The weak interaction of X-rays with matter causes quasi none-destractiveness in comparison to other probes such as ions and electrons and thus allows for in situ or operando analysis. Nonetheless, radiation induced damage can become an issue especially for experiments which have a long exposure, or high radiation dose per area (focused beam) and can be non-neglectable. 

Parent L, Twiss MR and Campbell PGC (1996) Influences of natural dissolved organic matter on the interaction of aluminum with the microalga chlor-ella a test of the free-ion model of trace metal toxicity. Environ Sci Technol 30 1713-1720. Pejovic-Milic a, Arnold ML, McNeill FE and Chettle dr (2000) Monte Carlo design study for in vivo bone aluminum measurement using a low energy accelerator beam. Appl Radiat Isot 53 657-664. 

The mechanism of physical extraction for analytical purposes always involves the bombardment or irradiation of a sample with an ion or laser beam, respectively [58, 59]. These processes are typically known as sputtering and ablation, respectively [60]. The interaction results in the volatilization of matter, in the form of solid fragments, neutral particles, or ions. While solid fragments need to be further divided before being introduced into an analyzer, neutral or charged particles can be detected directly with the appropriate technology. Nonetheless, post-extraction... 

As noted earlier, the transmission of radiation in matter can be pictured as a momentary retention of the radiant energy by atoms, ions, or molecules folk)wed by reemission of the radiation in all directions as the particles return to their original state. With atomic or molecular particles that are small relative to the wavelength of the radiation, destructive interference removes most but not all of the reemitted radiation except the radiation that travels in the original direction of the beam the path of the beam appears to be unaltered as a consequence of the interaction. Careful observation, however, reveals that a very small fraction of the radiation is transmitted at all angles from the original path and that the intensity of this scanered radiation incretises with panicle size. 

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