摘要:

AbstractTypical optical defects in glasses with a high lead content were examined by backscattered electron imaging (BSI), quantitative energy‐dispersive x‐ray spectroscopy (EDS) and windowless EDS (WEDS) in a scanning electron microscope (SEM) and by quantitative wavelength‐dispersive spectroscopy (WDS) in an electron probe micro‐analyser (EPMA). Most of the images were obtained by using a backscattered electron (BSE) detector of high efficiency and excellent atomic number (Z) resolution (ΔZ= 0.3). The observations showed the presence of cords of varying shape, diameter (10–200 μm) and composition, spherical inclusions and fractures; the fractures were found to be associated with regions of materials of lowZwhich have developed gas under electron beam irradiation. Quantitative WDS and EDS microanalyses performed on the cords showed the presence of about 3 wt.% of Al2O3and 2 wt.% of ZrO2, originating from the interaction, at the interface, of the glass and the refractory material used to hold the melted glass, and a lead content lower than the matrix. A high lead content was found, however, in the spherical inclusions. WDS and WEDS showed the presence of carbonates in the low‐Zregions, which probably developed CO2under electron beam irradiation. These morphological and microchemical results are of great importance in clarifying the origin, and hence finding the means of avoidance, of def

ISSN:0049-8246    

DOI:10.1002/xrs.1300210302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe relative L‐shell x‐ray intensities of Sm, W, Ir, Au, Hg, Pb and U were measured using a Cd‐109 radioisotope source and a Si(Li) detector. The measured relative intensities were compared with the theoretically calculated values due to Scofield, computed for the present excitation energy of 22.6 keV. The experimental results were found to agree with theory in most

ISSN:0049-8246    

DOI:10.1002/xrs.1300210303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA significant shift from the theoretical position of the Compton peak was observed in a graphite sample using Rh Kα radiation. The magnitude of the Rh KαComptonpeak shift depends on both the thickness of the graphite sample and the x‐ray beam diaphragm used. The larger the specimen thickness or the beam diaphragm size, the greater is the magnitude of the Compton peak shift. This Compton peak shift is interpreted as being due to the change in the ‘effective’ scattering angle, and it occurs with very light elemen

ISSN:0049-8246    

DOI:10.1002/xrs.1300210304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractEnergy‐dispersive x‐ray fluorescence (EDXRF) analysis using the fundamental parameters approach was used for the multi‐elemental analysis of Prestea (Ghana) gold ore (mill‐head samples). A model was obtained for the analysis based on the determination of the average total absorption in the ‘dark matrix’ (elements present but unable to be determined with the EDXRF spectrometer) of characteristic x‐rays of elementiper percentage of the dark matrix (a −Di%). The analytical procedure was validated using the reference sample IAEA SOIL‐7. There was good agreement between the model and

ISSN:0049-8246    

DOI:10.1002/xrs.1300210305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractEstablished methods for measuring the incident angle related to XRF when radioisotope annular sources are involved are briefly discussed. As an alternative technique, a direct measurement of the incident angle from the measured spectrum of the Compton scattered energy was developed. Analysing published experimental data, the limit of validity of this new approach is defined and it is established that for the sensitivity determination only the spectral data are required.

ISSN:0049-8246    

DOI:10.1002/xrs.1300210306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe variation in the value of the mass attenuation coefficient of x‐rays in aluminium was studied by counting photons under various positions in the photopeak employing a proportional counter spectrometer system with a good geometrical set‐up. The effect of (small angle) scattering was also examined using three different sets of collimators of diameter 9, 6 and 3 mm and employing both a pure x‐ray source (55Fe) and a mixed radiation source (57Co). The μmvalues obtained at the FWHM position for each set of collimators agree closely with the theoretical

ISSN:0049-8246    

DOI:10.1002/xrs.1300210307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractInvestigations by means of x‐ray photoelectron spectrometry, electron probe microanalysis, x‐ray fluorescence analysis, imaging x‐ray fluorescence analysis, x‐ray diffraction and secondary ion mass spectrometry were performed to quantify thin GexCyOz: H films. The films were prepared by r.f. plasma deposition of tetraethylgermanium in a parallel‐plate system and in a two‐rod discharge system with magnetron enhancement. The results of these investigations indicated that depth profiling delivers a homogeneous composition, with the exception of the outermost surface. At a constant flow‐rate of tetraethylgermanium, the film density and the Ge/C atomic ration increase with increasing r.f. power density towards a maximum of 3.5 g cm−3and 0.5, respectively. The hydrogen content does not change significantly. At low r.f. power densities there is a considerable increase in oxygen. There is no evidence for crystalline germanium carbide. Magnetron enhancement causes an increasing deposition rate and an inhomogeneous deposition in the lateral directi

ISSN:0049-8246    

DOI:10.1002/xrs.1300210308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractEnergy‐dispersive x‐ray fluorescence was used to analyse aerosol particles deposited on glass‐fibre filters. The blank filter contained several elements that interfered with trace elements found on the particles. The loaded filters were studied for composition and particle distribution of the few elements that can be analysed, which include lead. Samples provided by the Costa Rican Ministry of Health were analysed and the results pres

ISSN:0049-8246    

DOI:10.1002/xrs.1300210309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe accuracy of the results of steel x‐ray fluorescence (XRF) analysis using certain computation algorithms, differing in the way in which they consider the dependence of α coefficients on sample composition, was compared by means of the determination of chromium in steel standard samples, the chemical compositions of which represent possible compositional variations of 456 different types of high‐speed, high‐, medium‐ and low‐alloy steels. It is shown that in the XRF analysis of steels, the best accuracy is provided by algorithms in which this dependence is based on real variations in the concentration of interfering elements. Algorithms using constant influence coefficients may also give acceptable accuracy of XRF results provided that more exact calculation of equation parameters, by which the values of reduced element concentrations are obtained, are found. Recommendations for increasing the accuracy of these parameter calculations

ISSN:0049-8246    

DOI:10.1002/xrs.1300210310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300210311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY