ISSN:0049-8246    

DOI:10.1002/xrs.1300200402

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe geometrical properties of the x‐ray fluorescence (XRF) intensity related to the α‐parameterization were confirmed experimentally. A special sample stage was built to allow the rotation of the sample with the propagation plane (the plane defined by the incident and take‐off beam directions) and was coupled to an energy‐dispersive spectrometer. The device and the way in which it was carefully aligned with the collimated x‐ray beams are described. The fluorescence spectra of three NBS standard samples were measured for 16 different positions of the α angle. The incident and take‐off angles were both 45° for sample rotations between α = 0 and the maximum angle of 86°. XRF intensities from non‐enhanced lines do not show any dependence on α as predicted by theory. Enhanced lines, on the contrary, decrease in intensity when α increases, allowing the isolation of the primary emission by extrapolation to the l

ISSN:0049-8246    

DOI:10.1002/xrs.1300200403

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe difficulties that have been encountered in the electron probe microanalysis of Y3Al3O12garnet (YAG) insulator (bandgap width = 7 eV) are discussed. Although alumina (Al2O3), whose bandgap width is closed to 10 eV, should be a suitable standard for Al measurements, the experimental results are affected by large errors. Pure Al used as a standard provides very accurate results. Such a strange behaviour can be understood by assuming that a strong increase in the electrical conductivity of YAG occurs under irradiation. This hypothesis is corroborated by the occurrence of electrical breakdowns under certain beam conditions. The presence of an electric field within Al2O3can be revealed by the evolution of the Al Kα signal with irradiation time at low accelerating voltage (5 ke V). This evolution corresponds to a decrease in the internal field strength with a thermally induced increase in the electrical conductivity of the insulator

ISSN:0049-8246    

DOI:10.1002/xrs.1300200404

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

年代:1991

数据来源: WILEY

摘要:

AbstractA method for the energy‐dispersive x‐ray fluorescence analysis of geological materials in borax glasses without standards is described. The usefulness of the procedure was demonstrated by analysing five certified sedimentary rock reference materials for Al2O3, SiO2, CaO, TiO2, MnO and Fe2O3. The experimental results show reasonable agreement with the certified values. The method has a theoretical precision of 2% when dilution ratios of 6 and 12 are used. The actual precision of the method ranges from 4 to 15% for these element oxides. For the major oxides considered, the procedure can be useful when certified or well characterized geological standards are not availa

ISSN:0049-8246    

DOI:10.1002/xrs.1300200405

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

年代:1991

数据来源: WILEY

摘要:

AbstractA rapid procedure for the energy‐dispersive x‐ray fluorescence analysis of geological materials in borax glass beads for Al2O3, SiO2, CaO, TiO2, MnO and Fe2O3is presented. The method involves the addition of an internal standard, ZnO, to obtain approximate concentrations for the desired element oxides. Refined concentrations are then obtained through corrections for matrix and third‐element effects from theoretically calculated binary influence coefficients and third‐element correction factors using the binary coefficient approach combined with Tertian's correction algorithm. Data are presented for the determination of these major oxides in six Sedimentary Rock Reference Materials. A reasonable agreement between the experimental results and the certified values was obtained in mos

ISSN:0049-8246    

DOI:10.1002/xrs.1300200406

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe representation in Δω, Δ2θ space of the components of diffraction associated with a single‐crystal reflection is proposed as an alternative to the DuMond diagram. The capabilities of this representation in relation to one‐ and two‐crystal spectrometry are discussed. It is shown that these two types of system have close similarity and can be integrated within a general treatment using Δω

ISSN:0049-8246    

DOI:10.1002/xrs.1300200407

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

年代:1991

数据来源: WILEY

摘要:

AbstractAccurate tail‐to‐peak intensity ratios are extracted from the spectra produced in a Si(Li) detector by x‐rays of energies 2–10 keV. The widely used model of a surface layer of incomplete charge collection fails to explain the energy dependence of these data. The model is augmented to include loss of photoelectrons travelling back into the ICC layer from an interaction in the active silicon region; this gives excellent agreement with experiment. It is shown that the detection efficiency in the region of low x‐ray energy may be deduced from the tail‐to‐peak ratios, together with measurement of the thicknesses of the beryllium window and the metal contact; a potential source of error in measuring the latter by the popular fluorescence technique is

ISSN:0049-8246    

DOI:10.1002/xrs.1300200408

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe importance of the analysis of the green mix in the operation of sinter plants in integrated steel plants is described. The application of XRF in process control of sinter plants was investigated. The results suggest the replacement of time‐consuming wet chemical methods by a combination of XRF and IR absorption technique

ISSN:0049-8246    

DOI:10.1002/xrs.1300200409

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

年代:1991

数据来源: WILEY

摘要:

AbstractX‐ray fluorescence analysis was applied to the determination of the concentration of trace elements in the growth rings of trees. Some of these mineral elements can affect the growth and development of the plant. The results of the analytical measurements can provide information concerning the geochemical and atmospheric environment to which the tree has been exposed. It has been demonstrated that conventional x‐ray fluorescence equipment is adequate to perform such measurements but, more important, the high intensity available from synchrotron radiation is an ideal source to probe the spatial variation in the low‐level concentrations which can be transposed to an absolute temporal scale knowing the history of the tree. The ability to aperture or focus the synchrotron radiation to submillimeter size allows several points within individual rings to be analyzed, permitting a study of differences within a single growing season.Concentrations of mineral elements were determined in two types of tree samples, a cross‐section of the trunk of a small sassafras tree and an incremental core from a red oak. Two experimental arrangements were employed, a special energy‐dispersive x‐ray analyzer with a primary beam size of 0.5 mm and a beam line at the National Synchrotron Light Source where the radiation was focused and apertured to 50 μm × 1 mm. Concentrations as low as 1 ppm were determined for nine elements. Major year‐to‐year variations were observed, implying that cross‐ring elemental migration is slow (possibly negligible). The x‐ray technique is fast and non‐destructive, permitting the sample to be retained

ISSN:0049-8246    

DOI:10.1002/xrs.1300200410

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

年代:1991

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300200411

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

年代:1991

数据来源: WILEY