Microsonde de Castaing

La microsonde de Castaing (en anglais electron probe microanalyser, EPMA) est une méthode d'analyse élémentaire inventée en 1951 par Raimond Castaing. Elle consiste à bombarder un échantillon avec des électrons et à analyser le spectre des rayons X émis par l'échantillon sous cette sollicitation. Généralités Lors du bombardement d'un échantillon, certains électrons cèdent une partie de leur énergie cinétique à l'atome, provoquant l'éjection d'un électron de l'atome ; l'atome est dit « excité ». Si l'électron éjecté est proche du cœur, un électron d'une couche périphérique va descendre vers une couche d'énergie plus faible (l'atome se désexcite), et ce faisant, il va émettre un photon. Du fait de l'énergie de transition, ce photon va appartenir au domaine des rayons X. Il existe des microsondes seules (qui ne servent que pour l'analyse élémentaire), mais souvent, les microsondes sont couplées à un microscope électronique à balayage. L'analyse du spectre X peut se faire : *

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Géologie

vignette|Discordance angulaire de Siccar Point (Écosse) où des couches peu pentées de grès rouges du Dévonien recouvrent les formations verticalisées de grauwackes du Silurien. vignette|Carte mondiale

Minéralogie

La minéralogie est une science multidisciplinaire qui a pour objet les minéraux, leurs identifications, leurs caractérisations et descriptions, leurs analyses, leurs variétés et habitus, leurs class

Spectroscopie des rayons X

La spectroscopie des rayons X rassemble plusieurs techniques de caractérisation spectroscopique de matériaux par excitation par rayons X. Trois familles de techniques sont le plus souvent utilisées.

Weekly to monthly time scale of melt inclusion entrapment prior to eruption recorded by phosphorus distribution in olivine from mid-ocean ridges

Lukas Baumgartner, Stéphane Laurent Escrig, Mélina Manzini, Anders Meibom

Melt inclusions (MIs) hosted in euhedral olivine have been proposed to represent droplets of primary melt, protected from processes occurring near Earth's surface during eruption. The complex zoning of phosphorus (P) in some olivines and the presence of a P-depleted zone around MIs indicate a complex history for the host-MI system. We analyzed P in olivine and MIs from two mid-oceanic ridge basalt (MORB) samples from the Mid-Atlantic Ridge (MAR) by electron probe microanalyzer, secondary ion mass spectrometry (SIMS), and NanoSIMS. Phosphorus dendrites in olivine suggest an initial fast olivine growth followed by a stage of slower growth. Dissolution textures around some MIs were identified and were probably caused by adiabatic decompression melting. Based on diffusion modeling of P in olivine, we infer that olivine beneath the MAR remains in the system (1) for days to weeks after crystallization of P-rich lamellae, and (2) for a few hours after recrystallization of dissolved olivine. Dissolution and reprecipitation of olivine containing boundary layers suggests that most MIs might be affected by late post-entrapment processes.

Geological Soc Amer, Inc2017

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Experimental study and thermodynamic description of the Au-Cu-Ge system

Shan Jin, Christian Leinenbach

Phase equilibria in the Au-Cu-Ge ternary system, including the solid state phase relations at 450 degrees C as well as four vertical sections, were studied by means of scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Based on the present experimental results and the available information in the literature, a thermodynamic description of the Au-Cu-Ge ternary system has been developed using the CALPHAD (CALculation of PHAse Diagram) method. A consistent set of thermodynamic parameters for each phase was derived. The calculated phase diagrams and thermodynamic properties are in reasonable agreement with the experimental data obtained in the present study as well as those reported in the literature. (C) 2013 Elsevier B.V. All rights reserved.

Elsevier Science Sa2014

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Experimental investigation and thermodynamic modeling of the Au-Ge-Ni system

Shan Jin, Christian Leinenbach

Phase equilibria in the Au-Ge-Ni ternary system were studied by means of scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and differential scanning calorimetry. The phase relations in the solid state at 600 A degrees C as well as a vertical section at Au72Ge28-Ni were established. No ternary compound was found at 600 A degrees C. On the basis of the experimental phase equilibria data, a thermodynamic model of the Au-Ge-Ni ternary system was developed using the CALPHAD method. Thermodynamically calculated phase diagrams are shown at 600 A degrees C, in two vertical sections and the liquidus projection. Reasonable agreement between the calculations and the experimental results was achieved.

Springer Wien2012

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PHYS-405: Experimental methods in physics

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CIVIL-510: Quantitative imaging for engineers

First 2 courses are Tuesday 16-19h!This course will arm students with knowledge of different imaging techniques for practical measurements in many different fields of civil engineering. Modalities will range from satellite and drone imaging all the way down to x-ray microscopy with practical session