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A Story That Covers Almost A Century
Published in Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff, Radiation and Radioactivity on Earth and Beyond, 2020
Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff
Chemists working with aqueous solutions of radioelements noticed peculiar changes which could be attributed to the chemical action of radiation, and the early days of radioactivity and radiochemistry were also those of radiation chemistry. F. Giesel (1852–1927) already reported in 1903 that a gaseous mixture of hydrogen and oxygen is constantly liberated from aqueous solutions of radium bromide, and that the solution becomes brownish because of the generation of bromine. In 1914, A. Debierne (1874–1949) proposed an explanation for the phenomena observed in aqueous solution: the passage of radiation through water produces ionized molecules which react and form oxidizing and reducing entities, i.e., OH and H. The latter are chemically very reactive species which attack the molecules present in an aqueous system and are responsible for chemical changes. The hypothesis was far ahead of its time. Some of the proposed reactions proved to be untenable but the basic idea was confirmed in the early 1940s. In the following 2 decades, the radiation chemistry of water was very thoroughly investigated not only since it is a main constituent of the biosphere, but because of its important role in reactor technology as a coolant and moderator and in nuclear processing as a solvent.
Electron Beam Processing of Rubber
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
Rajatendu Sengupta, Indranil Banik, Papiya Sen Majumder, V. Vijayabaskar, Anil K. Bhowmick
Evidence indicates [28,29] that in most cases, for organic materials, the predominant intermediate in radiation chemistry is the free radical. It is only the highly localized concentrations of radicals formed by radiation, compared to those formed by other means, that can make recombination more favored compared with other possible radical reactions involving other species present in the polymer [30]. Also, the mobility of the radicals in solid polymers is much less than that of radicals in the liquid or gas phase with the result that the radical lifetimes in polymers can be very long (i.e., minutes, days, weeks, or longer at room temperature). The fate of long-lived radicals in irradiated polymers has been extensively studied by electron-spin resonance and UV spectroscopy, especially in the case of allyl or polyene radicals [30–32].
Ion Beam Modification of Polyimides
Published in Malay K. Ghosh, K. L. Mittal, Polyimides Fundamentals and Applications, 2018
When an energetic particle penetrates materials, it loses energy, mainly through four mechanisms: inelastic collisions with atomic electrons, inelastic collisions with nuclei, elastic collisions with nuclei, and elastic collisions with atomic electrons. For the keV to MeV energy range that is of interest, our main concern is the first item, the electronic interactions, because they are of dominating importance for radiation chemistry, particularly for excitation and ionization, radical formation, and cross-linking. According to Bohr’s classic theory, the electronic stopping power or LET can be obtained by multiplying the cross section (α) by the energy loss to electrons in the atom (ε) and integrating it from minimum energy loss to the maximum energy loss,
A DFT study on the addition and abstraction reactions of thiourea with hydroxyl radical
Published in Journal of Sulfur Chemistry, 2018
Mwadham. M. Kabanda, Kemoabetswe R. N. Serobatse
Because of the various biological, electrochemical, photochemical and radio-protective properties of TU and its derivatives, a research on their reactions with oxygen-based radical species is likely to have multidisciplinary outreach and impact significantly on chemical sciences research areas such as radiation chemistry, biochemistry, biological physics and electrochemical science. For instance, researchers in radiation chemistry have widely investigated the reaction between TU and hydroxyl (OH) radical to essentially understand the intermediate species produced in the ensuing radiation chemical reaction [20], such studies are of current interest as these species are considered to be possible intermediates in redox reactions of sulfur and nitrogen containing biomolecules; researchers in biophysical chemistry have extensively investigated the radical scavenging reaction mechanism of TU with several oxygen-based radical species, with the aim of understanding the radical scavenging properties of TU and thereby be able to protect biological macromolecules (such as DNA and protein) against oxidative stress [21–25]; researchers in corrosion science have also shown that TU and related compounds are effective corrosion inhibitors for mild steel and zinc pigments in aqueous solutions [18,26], which is a result of the fact that the presence of the lone pair electrons in TU molecules facilitates the electron transfer from the inhibitor to the metal, forming a coordinate covalent bond [27].