Radiation processing, role

Radiation processing plays an important role in industry, health care, agriculture and environmental technology. It involves the use of large radionuclide (gamma-radiation) sources and electron accelerators in industrial and institutional facilities. Quality assurance is vital for the success of this technology. In fact, it is indispensable for... 

In blends, alloys, composites and even in the multicomponent recycled polymers an extremely important, specific role is played by the interface between the components. Here is, where radiation processing offers a very specific tool of engineering [7],... 

Radiation processing plays a major role in nanotechnology [118], as structures as small as 10 nm can be generated with the aid of electron beams, ion beams or X-rays. lon-track-polymer membranes with track diameters between 10 and 100 nm (created by swift heavy ions penetrating the membrane) are used as... 

The Goeppert-Mayer two- (or multi-) photon absorption, mechanism (ii), may look similar, but it involves intennediate levels far from resonance with one-photon absorption. A third, quasi-resonant stepwise mechanism (iii), proceeds via smgle- photon excitation steps involvmg near-resonant intennediate levels. Finally, in mechanism (iv), there is the stepwise multiphoton absorption of incoherent radiation from themial light sources or broad-band statistical multimode lasers. In principle, all of these processes and their combinations play a role in the multiphoton excitation of atoms and molecules, but one can broadly... 

The decay of radioisotopes iavolves both the decay modes of the nucleus and the associated radiations that are emitted from the nucleus. In addition, the resulting excitation of the atomic electrons, the deexcitation of the atom, and the radiations associated with these processes all play a role. Some of the atomic processes, such as the emission of K x-rays, are inherently independent of the nuclear processes that cause them. There are others, such as internal conversion, where the nuclear and atomic processes are closely related. 

The principal components of atmospheric chemical processes are hydrocarbons, oxides of nitrogen, oxides of sulfur, oxygenated hydrocarbons, ozone, and free radical intermediates. Solar radiation plays a crucial role in the generation of free radicals, whereas water vapor and temperature can influence particular chemical pathways. Table 12-4 lists a few of the components of each of these classes. Although more extensive tabulations may be found in "Atmospheric Chemical Compounds" (8), those listed in... 

Ionizing radiation is unselective and has its effect on the monomer, the polymer, the solvent, and any other substances present in the system. The radiation sensitivity of a substrate is measured in terms of its G value or free radical yield G(R). Since radiation-induced grafting proceeds by generation of free radicals on the polymer as well as on the monomer, the highest graft yield is obtained when the free radical yield for the polymer is much greater than that for the monomer. Hence, the free radical yield plays an important role in grafting process [85]. 

Radical chemistry has undergone something of a renaissance in recent years. The phenomenon of CIDNP has played an important part in this. The growing interest in the role of radical processes in biological systems may stimulate the application of CIDNP in even wider fields in the future. The development of a practical device for radiofrequency amplification by the stimulated emission of radiation (RASER) may well be one such application. 

Along with atom particles and radicals, ions and electrons play an important role in radiation and plasma chemical processes. Ions and electrons are being produced and interact actively with irradiated matter both in gases and, especially, at the surfaces of solids (vessel walls, adsorbents, etc.). 

Excited particles (molecules, atoms, and ions) also play an important role in plasma and radiation chemical reactions. These particles interact actively with components of a gas (liquid) phase and with the adsorbed layer. These processes are discussed in detail in the next Chapter. 

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