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Journal of Thermal Analysis and Calorimetry
Authors: A. Sykuła-Zając, E. Łodyga-Chruścińska, B. Pałecz, R. E. Dinnebier, U. J. Griesser, and V. Niederwanger

instrumental methods such as differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and polarized light microscopy (PLM). The present thermal and X-ray analysis was performed on the currently most popular racemic mixture of BupiHCl

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Abstract  

A theoretical model of the enhancement effect in non-dispersive X-ray analysis is proposed. The considerations relate to a point source and detector localized in the same place (which is an approximation of the conditions of compact geometry). The results obtained in this work are different from those of other authors. Possibilities are suggested for the elimination of the influence of the enhancement effect on the results in non-dispersive X-ray fluorescence analyses.

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Surface contaminations on silicon slices and contaminations in surface layers deposited on thick silicon substrates were investigated by means of ion induced X-ray analysis. Sensitivity limits of foreign atoms are given for proton and nitrogen impact in dependence of projectile energies. They were derived using calculated K-shell ionization cross-sections as well as measured X-ray and γ-ray background spectra. The validity of the model used for characteristic cross-section calculations was proved by comparing the theoretical with experimental results. Some examples are given for the analysis of the basic material for the production of semiconductor electronic devices.

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Proton induced X-ray analysis has been studied by the 5 MV Van de Graaff of Tohoku University emphasizing on backing materials and angular dependence of background. The method has further been applied to analyses of some environmental samples. From experimental results, it was found that 4 μm Mylar foil among Formvar, Mylar and carbon gives sufficiently low background spectrum, high sensitivity and good mechanical strength. The detection limit is much improved at the backward direction with respect to the incident beam comparing with that at 90° which has usually been adopted. The analytical results on soil and aerosol samples were compared with those by the Atomic Absorption Spectrophotometrical method (AAS). Vanadium can easily be analysed by this method, but not by the AAS method. Milk and human milk were also analysed.

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Light output and response duration of isovalently doped zinc selenide single crystals depend on their element composition as well as on the dopant content and its distribution. For monitoring of these parameters, X-ray analysis suits best of all and was developed here. The ratio of Kα line intensities of Se and Zn was derived for the determination of ZnSe(Te) stoichiometry by taking into account the contribution of secondary excitation. The linear dependence of the TeKα intensity on the Te content was used for determining the latter. An annular 109Cd source was used for the excitation of Zn and Se Kα-lines and the Kα line of Te was excited by three 241Am sources. The measurement error (Sr) of ZnSe elemental composition was 0.01. The measurement error of the Te content was 0.06-0.09 in the range of 0.01-0.5% Te.

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X-ray analysis can be used to determine the quality of seeds, showing the cause of bad germination. X-ray images provide information on the internal structure and morphology of seeds, mechanical damage, percentage of empty and filled seeds, microfractures, possible embryo deformations and insect infestation. These techniques has been developed in Cuba for different X-ray sets. In this article we describe the suitable working conditions for 32 agricultural and forestry species. We also explained the main damages to seeds and their consequences for germination. If affected by insects, it could reduce the storage ability of grains.

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In this work we shall discuss the preliminary results of employing eleven different radionuclides for elemental X-ray analysis using a new analytical technique. This new technique mixes the radioisotope directly with the sample and this source sample is directly placed on the detector window which is protected by a thin plastic film from contamination. An equal atomic mixture of eight elements (Ti, Mn, Zn, Br, Zr, Ag, Sn and Ag) was prepared and doped separately with the eleven different isotopes (Pm-147, S-35, Ni-63, Na-22, Co-137, Co-57, Cd-109, I-125, Am-241, Zn-65 and Fe-55). The spectrum of each is shown herein with a discussion of the background, signal to noise ratio, corrected peak intensities, etc. Finally, the possible future applications of this technique with some of the isotopes are presented.

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Abstract  

Some theoretical aspects and limitations of XRF are discussed, including information depths in layered materials, characterization of inhomogeneous specimens, light element analysis, and radiation damage. Worked examples of applications of XRF and XRD are pigment analysis in delicate Chinese Paper, corrosion of glass, and leaching effects in soil-buried medieval coins.

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This work describes the thermal decomposition behaviour of cerium oxy-carbonate. DTA, TG, DTG and X-ray examinations were performed.

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Theoretical consideration concerning some possibilities for the elimination of matrix effects in non-dispersive X-ray fluorescence and absorption analysis are discussed. The theoretical treatment is concerned with the following methods: (a)  double-channel absorption edge analysis, (b)  concentration increase and dilution method in fluorescence analysis, (c)  fluorescence-absorption method, (d)  emission-transmission method, (e)  fluorescence-Compton scattering method, (f)  method of multicomponent analysis. On the basis of the derived formulas, nomographic methods of interpretation of the data are given. Using these methods it is possible to determine unambiguously the concentration of the relevant element. The formulas are also convenient for numerical interpretation. The introduction of the concept of “generalized sensitivity” allows the comparison of various radiometric methods.

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