[en] Two distinct radical species (AsO₄)^4- and (AsO₃)^2- created by irradiation in crystals of Nd₄D₂AsO₄ (DADA), clearly undergo (taking into account the deuterons) the following chemical reaction: AsO₃D^-+OD^-→AsO₄D₂^2-. The effects occurs at the antiferroelectric-paraelectric phase transition of the compound. Its essential feature is that the reaction is completely reversible i.e. that it can be reversibly triggered by the phase transition. This phenomenon is also observed on the same radicals in NH₄H₂AsO₄ (ADA)

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[en] Gamma irradiation of imidazole single crystals at 300 deg. K gives two radicals. Identification and detailed studies of their electronic and geometric structure have been made by ESR and ENDOR techniques. A study of the hydrogen bonded protons hyperfine tensor is made and let us conclude to the inexistence of movement and tunneling of these protons. The principal low temperature radical, produced by gamma irradiation at 77 deg. K has been also studied by ESR and a model has been proposed. (author)

[en] Two distinct radical species, (AsO₄)^4- and (AsO₃)^2-, created by gamma-irradiation in crystals of ND₄D₂AsO₄, undergo (taking into account the deuterons) the following chemical reaction: AsO₃D^-+OD^- reversible AsO₄D₂^2-. The effect occurs at the antiferroelectric-paraelectric phase transition of the compound. Its essential feature is that the reaction is completely reversible i.e. that it can be triggered by the phase transition, the direction of the reaction depending on the direction of passage of the Curie point. An analogy is presented with a biological process, namely the second step of the co-operative binding of oxygen on haemoglobin. (author)

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[en] This document gathers several study reports in the field of fundamental research. The first part contains studies which more particularly addressed nuclear physics: study of fission and fission products by fission product distribution measurement and nuclear spectroscopy, study of light nuclei by fast neutrons, study of the neutron electric dipolar moment). The second part concerns condensed matter physics: defects and effects of radiations in solids (pure metals, alloys, semiconductors, ionic crystals, molecular crystals or ferro-electric crystals with hydrogen bond), magnetism (study of magnetic properties of different materials such as transition element compounds and alloys, rare earth compounds and alloys, and actinides; studies of other magnetism-related issues: two-dimensional magnetic order, magnetic wall structure, critical phenomenon and phase transformation, crystalline field in refractory metals, influence of conduction electrons, free-radicals in solid phase; crystal structure and properties of transition element compounds, alloys and complexes; studies of semiconductor properties and behaviour). The third part deals with physical chemistry and biophysics: studies of steady free radicals, use of free-radical spin markers in biology, stereochemistry and conformation studies, studies of vegetal macromolecules, theoretical chemistry, chemically-induced nuclear polarisation, organic and analytic electrochemistry, studies of organic photochemistry, proton dynamics in the hydrogen bond, studies of molecular movement, studies of polymers. The fourth part concerns biology: protein structure and functions, biological membrane structure and functions, radiobiology, vegetal physiology, medical research. The last chapters address advanced techniques, general services (electronic paramagnetic resonance) and applied research (pollution study: purification kinetics of river water in its torrential regime)