Electron probe microanalyzer EPMA

In electron-optical instruments, e.g. the scanning electron microscope (SEM), the electron-probe microanalyzer (EPMA), and the transmission electron microscope there is always a wealth of signals, caused by the interaction between the primary electrons and the target, which can be used for materials characterization via imaging, diffraction, and chemical analysis. The different interaction processes for an electron-transparent crystalline specimen inside a TEM are sketched in Eig. 2.31. 

Electron-phonon interaction, 23 804 Electron probe microanalyzer (EPMA), 16 484, 488... 

Diffusion was promoted by heating the samples in a vacuum of about 6.5X10 Pa at 2000 2300 K in order to form a composition gradient between the molybdenum substrate and the rhenium layer. The composition gradient was investigated using an electron probe microanalyzer (EPMA). 

The compositions of both matrix powders pyrolyzed at different temperatures and composites were characterized by XRD. Mechanical properties of composites were measured by three-point-bending tests with 5mmx2mmx40mm specimens in an lnstron-5566 machine, operated at a crosshead speed of 0.5mm/min and a span of 24mm. The microstructures of composites both with and without boron were observed by electron probe microanalyzer (EPMA, JXA-8IOO, JEOL, Tokyo, Japan). 

For quantitative X-ray analysis, electron probe microanalyzers (EPMA, EPA, or EMMA) are able to determine the elemental concentration by X-ray emission from the microvolume of paint samples where a static electron beam interacts. However, due to inhomogeneity of paint samples nonquantitative... 

X-ray fluorescence (XRF) spectroscopy is a technique for the determination of elemental composition of materials, for elements greater than atomic number 11, present above 0.05% concentration [54-56]. The technique is similar to the electron probe microanalyzer (EPMA), and x-ray analysis in the electron microscope (see Section 2.7.1), except that the EPMA is used for local analysis, whereas XRF is a bulk technique. Exposure of the sample to an x-ray beam causes electrons to be ejected and outer shell electrons to fall into the vacancies, emitting x-rays of discrete energy. Characteristic energies are associated with specific elements, and the x-ray intensities are related to the concentration of the element in the sample. There are problems with this direct association of x-ray intensity and concentration, due to absorption by the matrix, but standards and software programs are available to calculate elemental... 

WDS is another technique utilized for elemental chemical analysis in reverse engineering. EDXA and WDS are usually used in conjunction with SEM, or an electron probe microanalyzer (EPMA). EPMA is a nondestructive elemental analysis technique, similar to SEM but with a more focused analysis area. It works by rastering a micro volume of the sample with an electron beam typical of an energy level of 5 to 30 keV. It then collects the induced X-ray photons emitted by the various elemental species and quantitatively analyzes the spectrum with precise accuracy, up to ppm. In contrast to EDXA, WDS analyzes the electron diffraction patterns based on Bragg s law and has a much finer spectral resolution and better accuracy. WDS also avoids the problems associated with artifacts in EDXA, such as the false peaks and the background noise from the amplifiers. The noise intensity that appears in... 

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