Analytical techniques electron probe microanalysis

The complex of the following destmctive and nondestmctive analytical methods was used for studying the composition of sponges inductively coupled plasma mass-spectrometry (ICP-MS), X-ray fluorescence (XRF), electron probe microanalysis (EPMA), and atomic absorption spectrometry (AAS). Techniques of sample preparation were developed for each method and their metrological characteristics were defined. Relative standard deviations for all the elements did not exceed 0.25 within detection limit. The accuracy of techniques elaborated was checked with the method of additions and control methods of analysis. 

Analysis for traces of substances that act as catalysts for reactions can be both highly specific and sensitive. Calculations of the type carried out by Yatsimirskii indicate that, if the rate of a catalytic reaction can be measured spectrophoto-metrically with a change in concentration equivalent to 10 moles/1, and if the catalytic coefficient amounts to 10 cycles/min, the minimum concentration of catalyst that can be measured by following the reaction for 1 min is about 10 moles/1. Such sensitivities can be attained by few other analytical techniques. Tolg considers only mass spectroscopy, electron-probe microanalysis, and neutron-activation analysis methods applied to favorable cases to have better limits of detection than catalytic methods. 

The toxicity of the mineral is such that quantitative characterization of erionite is extremely important. Samples should be characterized by using one or more of the following techniques (1) powder X-ray diffraction, (2) electron probe microanalysis or inductively coupled plasma-mass spectroscopy, (3) scanning electron microscopy equipped with wavelength dispersive spectroscopy (WDS) and/or energy dispersive spectroscopy (EDS), (4) transmission electron microscopy equipped with WDS and/or EDS and selected area electron diffraction, and (5) similar or better analytical techniques. 

X-Ray Fluorescence Spectrometry Terms associated with the broad technique of X-ray fluorescence spectrometry are electron spectrometry. X-ray spectrometry, electron microscopy, analytical electron microscopy, scanning transmission electron microscopy (STEM), electron diffraction, electron probe microanalysis. Auger electron spectrometry. X-ray photoelectron spec-... 

With respect to other major literature on or related to XRE, are chapters in various analytical series and individual books. Two chapters are in the first edition of the famous Treatise on Analytical Chemistry. Comprehensive coverage of X-ray methods absorption, diffraction, and emission is provided by Liebhafsky et al. (1964) in a 90-page chapter in the section on Optical methods of analysis (E. J. Meehan, section advisor). This is immediately followed by the chapter by Wittry (1964) on X-ray microanalysis by means of electron probes. Chapters on relevant topics appearing in the other well known series on analytical chemistry. Comprehensive Analytical Chemistry, are by Beretka (1975) (Analytical applications of electron microscopy) with a brief mention of the XRF-based technique electron probe... 

Standard laboratory techniques are used to characterize samples for a failure analysis. These techniques include metallography, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), Fourier transform-infrared analysis (FTIR), and analytical chemistry. 

Optical microscopy (OM), polarized light microscopy (PLM), phase contrast microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) are the methods normally used for identification and quantification of the trace amounts of asbestos fibers that are encountered in the environment and lung tissue. Energy-dispersive X-ray spectrometry (EDXS) is used in both SEM and TEM for chemical analysis of individual particles, while selected-area electron diffraction (SAED) pattern analysis in TEM can provide details of the cell unit of individual particles of mass down to 10 g. It helps to differentiate between antigorite and chrysotile. Secondary ion mass spectrometry, laser microprobe mass spectrometry (EMMS), electron probe X-ray microanalysis (EPXMA), and X-ray photoelectron spectroscopy (XPS) are also analytical techniques used for asbestos chemical characterization. 

Many interesting studies have been published on the effects of a polluted atmosphere on stone with emphasis on the more chemical aspects [39,40,41]. The physical-chemical analytical techniques employed in the study of building materials provide very accurate qualitative and quantitative results on the alterations related to the patina or crust as well as the bulk chemistry of the exposed stone. Scanning electron microscopy (SEM), Electron probe X-ray microanalysis (EPXMA), Fourier-transform infrared analysis (FTIR), X-Ray diffraction (XRD), energy dispersive X-Ray fluorescence, Ion Chromatography, are the most used techniques for the studies of sulphate black crusts as well as to evaluate the effect of exposition time of the sample stone to weathering[42,43]. 

Routine inorganic elemental analysis is carried out nowadays mainly by atomic spectrometric techniques based on measurement of the energy of photons. The most frequently used photons for analytical atomic spectrometry extend from the ultraviolet (UV 190-390 nm) to the visible (Vis 390-750 nm) regions. Here the analyte must be in the form of atoms in gas phase so that the photons interact easily with valence electrons. It is worth noting that techniques based on the measurement of X-rays emitted after excitation of the sample with X-rays i.e. X-ray fluorescence or XRF) or with energetic electrons (electron-probe X-ray microanalysis or EPXMA) yield elemental information directly from solid samples, but they will not be explained here instead they will be briefly treated in Section 1.5. 

Linked with its qualities, assessed above, as an imaging and structural tool, the STEM assumes prime importance when considered as a microanalytical instrument. As pointed out in the introduction, the interaction of the fine probe in STEM with, potentially, only a small volume of the sample suggests the possibility of microanalysis on a scale hitherto unattainable. Two main areas will be considered here -the emission of characteristic A -rays by the sample, and the loss of energy from the primary beam in traversing the latter. Ideally, a fully equipped analytical electron microscope will utilize both techniques, since, as a result of the relative positions of A"-ray detector and the energy loss spectrometer in the electron optical column, simultaneous measurements are possible. However, for the sake of convenience we will consider the methods separately. 

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