[en] The measurement of gamma-radiation quantities, e.g., absorbed dose in materials such as water, plastics, foodstuffs, is a convenient means of quality assurance in radiation processing. A new dosimetry system, called the “Opti-Chromic” dosimeter, is commercially available in large batches for use as a routine measurement system in the absorbed dose range 10 to 2 x 10⁴ Gy. This dose range covers most food irradiation applications. A statistical evaluation was made of the reproducibility of this dosimeter for measuring doses appropriate for the disinfestation and shelf-life extension of many foods, namely 10 to 2 x 10³ Gy. In addition, the small dosimeters were used to map absorbed dose distributions in boxes of foods having four different bulk densities (grapefruit, lemons, peanuts, and wheat bran). It is demonstrated that the dosimeters are rugged and stable enough to be used over a wide temperature and humidity range, and, in fact, can be placed in such environments as the inside of citrus fruits without adverse effects on their ability to give satisfactory dose assessment. (author)

[en] It is shown that using simple trial functions for describing the inhibition processes of positronium formation, in the framework of the spur model, can lead to some quantitative information regarding both the reactivity of solutes towards damp and dry electrons or positrons and the solvation properties of solvents. The solutes used as probes are the chloride, bromide, iodide and nitrate ions and the solvents investigated include water, methanol, ethanol, N-ethylacetamide, dimethylsulphoxide and hexamethylphosphorotriamide. (author)

No abstract available

[en] Irradiation of an electrochemical cell with a semiconductor (TiO₂, SrTiO₃) anode, a metal cathode, and an aqueous electrolyte solution with ionizing radiation (accelerated electrons with the energy 4 MeV, X-radiation 70 keV, γ radiation, and neutron radiation of a nuclear reactor) stimulates the process of electrochemical decomposition of water resulting in O₂ evolution at a semiconductor anode. The radiation-electrochemical process is caused by generation in the semiconductor of minority carriers (holes) necessary for anodic oxidation of water. The possibility of converting by radiation-electrochemical means the energy of ionizing radiation into chemical energy has been thus demonstrated. (author)

[en] Transient intermediates formed on γ-radiolysis of CHI₃ in 3-methylpentane glass at 77 K were characterised from the study of absorption spectra, changes induced by different scavengers, matrix viscosity, optical bleaching, photoionization of NNN'N'-tetramethyl-p-phenylenediamine, and identification of stable end products. Variation of stable products yields and intensity of absorption bands with solute concentration has been explained by solute aggregation at 77 K. It is concluded that the optical absorption bands at 450 and 600 nm are due to CHI₃⁺ and CHI₂, respectively. (author)

[en] The radicals formed on γ radiolysis of N-acetyl-L-valine in the polycrystalline state at 77 K, at ambient temperature (303 K), and on subsequent warming over the range 77 to 440 K are reported. Radical anions CH₃C(O^-)NHCH(CH(CH₃)₂)COOH and neutral radicals CH₃CONHCH(CH(CH₃)₂), believed to be decomposition products of radical cations, were observed at 77 K. On warming the radical anions decay to nonparamagnetic species while the neutral radicals abstract hydrogen from parent molecules to produce the radicals CH₃CONHC(CH(CH₃)₂)COOH and CH₃CONHCH(C(CH₃)₂)COOH. The α-carbon radicals are the predominant radical species at room temperature. Further warming causes these radicals to decay over the temperature range 350 to 440 K. A mechanism for the radiation degradation is suggested, based upon the identification of the radical intermediates and the measurement of their concentrations, and the observation that the major volatile product is carbon dioxide. (author)

[en] A narrow single line superimposed on radical-cation spectra has been observed by the ODESR technique in X-irradiated squalane solutions of durene and triethylamine. This line has been ascribed to electrons participating in the primary pair recombination based on: (i) the narrow width of the line, (ii) its disappearance on addition of electron acceptors, (iii) the characteristic temperature dependence of the line intensity. (author)

[en] Reference is made to the paper by Buehler about the transients observed in electron irradiated pure liquid CCl₄. It was concluded that the 340 nm transient should be assigned to a CCl₂ radical and the 475 nm species mainly to CCl₃⁺ and an ion pair (CCl₃⁺ --- Cl^-). The present paper concludes, from charge transfer reactions to scavengers and formation kinetics considerations, that the UV-transient should be assigned to the radical cation CCl₄⁺ and that the visible band is due to a solvent separated ion pair (CCl₄⁺ --- Cl^-) formed by geminate (fast part) and free (slow part) ions. (U.K.)

[en] The efficiency of the reaction of the pre-solvated electron with selected solutes in various polar media has been correlated to three parameters: the ratio of the ion-pair recombination distance (rsub(c)) to the electron thermalization length (r₀), their difference (r₀) - rsub(c) and the solvent trapping frequency. (author)

[en] Absorption spectra of the anion radical of decafluorobenzophenone (DFB) obtained on γ-radiolysis in various matrices were found to be blue shifted on warming. Spectra of the anion is blue shifted by as much as 0.32 eV in MTHF matrix containing 0.7 M ethanol (EtOH). In nonpolar 3 MP matrix containing 0.5 M isopropylalcohol (iPrOH) the extent of blue shift was found to be much lower, viz. 0.12 eV. Ketyl radical absorption obtained on warming results from protonation of the anion radical. The fact that warming of the matrix is a prerequisite for the ketyl radical formation seems to indicate that proton involved must be arising out of an ion-molecule reaction rather than the matrix itself. The formation of anion radical of DFB in 3 MP was found to be possible only in the presence of solute such as isopropylalcohol and triethylamine (TEA) where the positive hole is concomitantly trapped by the solute. (author)