Summary Nuclear microprobe analysis has been used to study the aqueous sorption of cadmium and selenium at different solution pH values onto hydroxyapatite. By coupling Particle Induced X-ray Emission (PIXE) and Rutherford Backscattering (RBS) microanalyses, we have quantified the concentration and modeled the depth distribution of Cd and Se in particles of calcium hydroxyapatites (HAP). No cadmium precipitation was observed for those experiments in which the initial concentration was greater than the solubility of Cd(OH)2 and CdCO3 at solution pH=9 and 12. The observation of the solid by transmission and scanning electron microscopies, SEM and TEM, showed the polycrystalline nature of the particles; these particles were constituted by aggregated nanocrystals. This additional information allowed us to interpret the incorporation of Cd and Se into the apatitic substrate as a penetration in the intra-particle porosity generated by this aggregation of crystals and probably not as diffusion in the solid structure.

The coupling of X-ray photoelectron spectroscopy XPS) and nuclear microprobe analysis (NMA) using resonant reactions O-16(alpha,alpha)O-16 and C-12(p,p)C-12 at 3.05 and 1.725 MeV, respectively, is particularly adapted to the characterization of thin oxidation layers onto pyrites. XPS pen-nits to determine both oxidation state and chemical environment of S and Fe. NMA gives an information about spatial distribution and chemical composition heterogeneity of oxidation products. Pyrites oxidized in acidic medium produce few solid components. Only Fe-II sulfate is detected on the oxidized pyrite surface. In carbonate medium, oxidation layer is more complex, Iron is mainly with a (+II) oxidation state under siderite or Fe-II, sulfate form. As illustrated by the comparison of Fe3p and Fe2p(3/2) peaks, iron has an (+III) oxidation state to a minor extent under alpha -FeOOH and Fe-III sulfate forms from the first oxidized pyrite layers. Sulfur oxidation induces intermediate species (polysulfides and sulfoxyanions as S2O32- also evidenced in solution) indicating that oxidation occurs at solid state. NMA has shown that oxidation occurs only on localized points of pyrite surface, with oxidation layers showing spatial distribution and thickness heterogeneities. (C) 2001 Published by Elsevier Science B.V.

The evolution of the passivating layer (during the first reduction/reoxidation cycle, in function of the number of reduction/reoxidation cycles and with the storage of the electrode in the electrolyte) formed at the surface of a lithiated carbon electrode in LiCF3SO3/carbonates mixture electrolyte has been followed by using 1 MeV 4He+ induced Rutherford Backscattering Spectrometry (RBS). Two RBS simulation codes "RUMP" and "PERM" , whose approaches are different, have been applied to the treatment of the RBS data and have allowed to obtain informations about the structure (thickness and atomic elemental composition) of the passivating layer. These two codes provide similar results. The passivating layer has a thickness in the range 20-30 nm. Its structure appears to be complex with the presence of two different sublayers respectively composed of the reduction products of the salt in the inner sublayer (with the main presence of fluorine and sulphur indicating the possible existence of LiF and Li2S) and reduction products of the solvents in the outer sublayer (with a high concentration in oxygen indicating the presence of Li2CO3 and RCO3Li where R is an alkyl radical).

We studied the influence of the anion of lithium salts dissolved in a solution based on propylene carbonate (PC), ethylene carbonate (EC) and dimethyl carbonate (DMC) on the electrochemical properties of a petroleum coke (LONZA) and on the petroleum coke/electrolyte interface. We explored a correlation between the electrochemical properties and the surface chemistry of this coke using infrared spectroscopy, Rutherford backscattering spectrometry, fluoride selective electrode and standard electrochemical techniques. The different techniques show that LiF is a major product of the reduction of LiAsF6 and LiBF4 and a minor product of the reduction of LiCF3SO3 and LiTFSI. Alkyl carbonates are generated by reductions of the carbonate solvents to an extent which is independent of the anion of the lithium salt. Electrochemical behaviour of the coke is discussed with regard to the composition of the passivating layer. We found better cycling behaviour and greater lithium stability with LiCF3SO3 and LiTFSI.

Stoichiometric local characterizations of YBaCuO oxides have been performed using a 1.4 MeV deuteron microbeam. A beam with a size of 10 × 15 μm2 allows the observation of variations of x = 0.2 in sintered YBa2Cu3O7−x. Local variations of oxygen stoichiometry in a melt-textured sample, correlated with the microstructure, have been observed. In spite of the degradation of the sample under the beam, oxygen measurements seem to remain significant for doses above 1018 ions/cm2.

The improvement of the oil production forecast and the recovery strategy is closely related to a better understanding of the oil reservoir wettability. As there is a need of a description of the spatial distribution of wettability down to the pore scale, new tools allow to enhance very fine scale wettability contrasts and to evidence the importance of mineralogy. Among them, we propose to use the nuclear microprobe analysis (NMA) for the qualitative and quantitative study of the organic matter/mineral interactions i.e. the description of the reservoir rock wettability. NMA, field emission SEM and AFM techniques are used to image and study the mechanisms and kinetics of the sorption of the organic matter on model samples: the organic film thicknesses and the major elemental contents (carbon and nitrogen) are measured.

Nuclear microprobe analysis is used to quantitatively characterize fluid inclusions in halite. We show the presence of three types of fluid inclusions located near the surface of rocksalt sections: hydrocarbon, brine + hydrocarbon and brine-rich inclusions. The elemental salt and and inclusion stability has been verified under microbeam investigation with a beam current density up to 26 pA/smm2. Oxygen and carbon detection limits of 10−4 molcm−3 were achieved. Moreover, the composition of these fluid inclusions appears to be strongly inhomogeneous.

Grazing angle neutron reflectometry, optical and mechanical roughness profilometry techniques have been used to study the effects of the polishing operations on the surface of Borkron Schott glass (special borosilicate glass for neutron optics applications) as the polishing tool pressure P and the mean grain size of the polishing powder PHI. The neutron reflectivity investigations have shown that there is formation of a layer at the surface glass substrate. This layer is less dense than the bulk substrate and its thickness is around 60 angstrom. The optical and mechanical profilometry measurements have shown that both roughness and waviness decrease with P and PHI. All the experimental results show a good correlation between the neutron refractive index, the thickness and the roughness of the surface layer and the waviness of the glass surface with the two mechanical polishing parameters. The previous techniques have been completed by secondary ion mass spectroscopy and atomic force microscopy measurements.

Instrumental neutron activation analysis (INAA) of the bones of a 6th century case ( AD ) of hypertrophic osteoarthropathy (HOA) showed high levels of Zn, Mn and K in the periosteal new bone. The concentration of Zn in the periosteal new bone appeared to be biogenetic in origin and connected with active mineralization processes in the abnormal bone tissue. Manganese and potassium concentrations were, at least partly, related to diagenetic processes.

Grazing angle neutron reflectometry, optical and mechanical roughness profilometry techniques have been used to study the effects of the polishing operations on the surface of Borkron Schott glass (special borosilicate glass for neutron optics applications) as the polishing tool pressure P and the mean grain size of the polishing powder Ф.

The physico-chemical characteristics of the pigments used in oil paintings supply valuable informations concerning the age of the work and sometimes even the geographic origin of the ores used.

Thick targets (mica) and thin hydrogen layers obtained by ionic implantation of protons in silica are used to establish the excitation function of the nuclear resonant reaction1H (15N, α γ)12C. Two main resonances in the energy gap explored were observed. Their FWHM and the cross section at ER are specified. The experimental conditions required and the performances allowed, using this reaction to determine hydrogen depth profiles in the near surface region of solids, are presented. Examples concerning borosilicates, leached in aqueous medium, are given.

The method used is briefly described. It is based on direct observation of the following resonant nuclear reactions: 1H(15N, αγ)12C, 23Na(p, αγ)20Ne and 27Al(p, γ)28Si. The possible performances of these techniques, in the non-destructive exploration of the first few microns of the glass surface, are presented. The choice of appropriate experimental conditions required for the investigation of concentration profiles without secondary effects is discussed. A few examples, showing the profiles obtained after aqueous leaching of glasses with different temperature and time conditions, are given.

Abstract  Thin targerts obtained by sodium implantation in a layer of silica were used to establish the true excitation functions of the nuclear reactions in question. Many resonances are observed in the energy range explored and their half-widths and the cross-section values at the maxima have been evaluated. The potential performances allowed by these resonant nuclear reactions are examined from the viewpoint of their application to measurements of sodium concentration profiles in the surface region of solids.

RESUME.~ Après une description sommaire des techniques nucléaires d'analyse ba­ sées sur l'observation directe de réactions résonnantes et sur la rétrodiffusion élastique de particules chargées,des exemples de profils de concentration se rapportant à des verres lixiviés en milieu aqueux sont présentés. ABSTRACT.- Nuclear analytical techniques based on direct observation of resonant reaction and charged particle backscattering are briefly described.Few depth profile examples concerning leached glasses are shown.