[en] The gas phase Co⁶⁰ radiolysis of mixtures of HBr and H₂S has been studied at room temperature. In agreement with earlier studies HBr enhanced the hydrogen yield from H₂S by reacting with thermal electrons. However, using SF₆ as a competitive electron scavenger it was shown that (HBr)₂ dimers are not the only species reacting with electrons to form hydrogen. The excess capture rate was first order in both [HBr] and [H₂S]. Reaction mechanisms are proposed. From this and earlier studies the reactions of (H₂S)₂ species appear to be relatively slow. (author)

[en] A summary is presented of experiments on the use of alpha sensitive plastic films for uranium exploration and prospecting. The simulation experiments were performed both in the laboratory and in the field, and it was found that this new tool can be used very profitably. The applied work has helped in locating a few new regions of high radon activity. Also, the experiments indicate a higher efficiency of exploration than is achieved using the conventional gamma detection technique. (author)

[en] 1,1-Diphenylethylene (DPE) has been irradiated with 20 ns pulses of 15 MeV electrons at room temperature in dichloromethane solution and at 77 K in a 1:1-n-buty-chloride-isopentane matrix with ⁶⁰Co-γ-rays. A comparison of the results led to the following conclusions. Associated dimer radical cations (M)₂⁺ (absorbing at 395 nm and between 1000 nm and 1200 nm) are generated within the pulse. They form an equilibrium (M)₂⁺=sup(ksub(e)) M⁺+M(k sub(e)=(2.0+-0.4) x10⁶s^-1). The decay of the radical cations follows first order kinetics (k₀=(1.1+-0.3)x10⁵ s^-1) probably due to a reaction with traces of an impurity. Thereby free radicals are formed, absorbing between 300 nm and 350 nm (peak at 335 nm). The radicals decay according to a second order process ((2k/epsilon) = (3.2+-0.3) x 10³cm s^-1) by mutual deactivation. Ethanol causes a diminution of the initial spectrum, since it competes with DPE for solvent radical cations S⁺ Ethanol reacts with M⁺ with (ksub(EtOH+M⁺)= 1 x 10⁸M^-1 s^-1 (author)

No abstract available

[en] The yields of various products formed in γ-irradiated nitrate ices, viz NO₂^-, H₂O₂, O₂ and H₂, have been measured at different nitrate concentrations. Daniel's method of partition of yields has been employed to evaluate the direct and indirect effect contributions to the yields of the first three products. G(H₂) is close to zero at all nitrate concentrations above approximately 0.5 mol dm^-3. The mechanism of product formation has been discussed in the light of various reactions put forth to explain the radiolysis of fluid aqueous nitrate solutions. The effect of various scavengers for the primary species on the product yields has also been investigated. From this it is inferred that nitrate is able to scavenge both the reducing species, viz. H and e^-sub(m) giving nitrite and possibly also the holes (h⁺sub(m)) giving O₂, and excited water molecules (H₂O*) giving H₂O₂ and additional nitrite. (author)

[en] The radiolysis of N₂O saturated-aqueous solutions of benzene-¹⁴C has been examined using radio-liquid chromatographic methods to follow the quantitative aspects of the reactions of hydroxycyclohexadienyl radicals. In the absence of a radical oxidant, at least five important products are produced. The total yield of 5.8 observed for the incorporation of benzene into products accounts for essentially all of the radicals initially produced from the water. Dimeric products predominate with a total yield of 4.1. Phenol is produced with a yield of only 0.8 indicating a disproportionation/ combination ratio for hydroxycyclohexadienyl radicals of < = 0.4. In the presence of 2mM ferricyanide the hydroxycyclohexadienyl radicals are quantitatively oxidized to phenol with no trace (< 1%) remaining of dimeric or other high molecular weight products. The initial yield for phenol formation (6.0 molecules/100 eV) provides a measure for OH production in N₂O saturated aqueous solutions. (author)

[en] In this review some examples are used to show that ion implantation may be a useful tool in the study and application of colour centres and radiation damage in insulating materials. Examples include the diagnostic use of implantation to examine the role of trace impurities in the complex personnel dosimeter system of LiF:Mg:Ti:O. Academic studies to test colour centre models in alkali halides are presented in which the extremes of radiation flux obtainable by ion and molecular ion implantation have been compared to distinguish between alternative defect models. Finally, it is shown that ion implantation may be used to make optical waveguides in insulators. In the work presented using silica glass most of the increase in refractive index results from radiation damage rather than chemical effects of implantation. (author)

[en] Radiation effects on Fischer-Tropsch synthesis has been examined using high dose rate electron beams and Fe-Cu-diatomaceous earth catalyst. Yields of saturated hydrocarbons were found to increase by irradiation, but the yields of these compounds were decreased by raising reaction temperature without irradiation, suggesting the presence of radiation chemical process in catalytic reactions. (author)

[en] The subject is reviewed under the following headings: radiation sources; major research and development centres; radiation sterilization of medical products; food preservation; radiation chemical processing (including: cross-linking, fibre-polymer composites); other polymerization processes (including: grafting). (U.K.)

[en] The formation of positronium in aqueous solutions of halides, sulfide and thiocyanate has been investigated. Inhibiting and enhancing reactions of positronium formation are found. The results are discussed in terms of the spur model. (author)