ISSN:0049-8246    

DOI:10.1002/xrs.1300220403

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

年代:1993

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300220404

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

年代:1993

数据来源: WILEY

摘要:

AbstractX‐ray spectroscopy has been widely used for chemical analysis since its discovery in 1895. X‐ray fluorescence (XRF) has been used for over 60 years for identifying the elemental composition in most kinds of samples and in combination with modern semiconductor detector technology XRF has developed into a versatile, multi‐element method. With the high X‐ray flux attainable from the synchrotron source, new spectroscopic techniques have become available, such as extended x‐ray absorption fine structure (EXAFS) and x‐ray absorption near‐edge spectroscopy (XANES), for studying the chemical states of the different elements. With the use of high‐intensity x‐ray microbeams all of these different analytical methods can be performed on a microscopic level. By scanning the microbeam over a sample, the distribution of different elements can be determined. A description of the basic principles of x‐ray microbeam spectroscopy, and the historical background, is given and comparisons with other techniques are discussed. Different techniques for focusing of x‐rays, detection and image reconstruction are described. Examples of applications and future perspectives are discussed with particular emphasis on capi

ISSN:0049-8246    

DOI:10.1002/xrs.1300220405

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe principles of sampling, sample storage and sample preparation prior to energy‐dispersive x‐ray spectrometry with special attention paid to the methods of obtaining representative samples of heterogeneous materials such as soil, biological and geological specimens are presented. Problems occur with losses of elements to be determined and also contamination of the sample. Sample preparation prior to analysis of environmental, biological and geological materials with and without chemical pretreatment is discussed. The procedure of sample digestion followed by preconcentration and separation of the elements to be determined is discussed. Reference materials are needed for testing the applied procedu

ISSN:0049-8246    

DOI:10.1002/xrs.1300220406

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

年代:1993

数据来源: WILEY

摘要:

AbstractRadioisotop‐excited x‐ray fluorescence is advantageously applied to many specific analytical problems. It is a method of choice forin situand on‐line analysis. There is a growing need forin vivodeterminations of many elements; radioisotope excitation offers some interesting possibilities. In addition to a review of published applications, current XRF activities in IAEA Laboratories are briefly desc

ISSN:0049-8246    

DOI:10.1002/xrs.1300220407

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe scattering of either the exciting or the characteristic radiation enhances and reduces the XRF intensity. The resultant enhancement has been calculated using exact differential scattering cross‐sections and employing an arithmetic integration. By using radioactive sources the scattering corrections for some thick pure targets were determined experimentall

ISSN:0049-8246    

DOI:10.1002/xrs.1300220408

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe method of total reflection in conical glass capillaries has been used for several decades for obtaining high‐intensity x‐ray microbeams of small spot size. A general problem with this technique is the small critical angle, which is energy dependent. There is a certain loss of intensity if many reflections occur in the capillary. Assuming parallel monoenergetic x‐rays, a simple relationship has been derived for the intensity enhancement as a function of the reflectivity of the glass and the number of reflections. The relationship was used to derive conditions for optimum intensity enhancement. Also for suboptimum conditions the relationship can be used to design entrance and exit diameters and length of the capillary. The model was also applied to a wedge‐shaped slit that consists of two total reflection

ISSN:0049-8246    

DOI:10.1002/xrs.1300220409

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

年代:1993

数据来源: WILEY

摘要:

AbstractX‐ray emission techniques for bulk and individual particle analysis (EDXRF, EPXMA, micro‐PIXE) were combined and applied in atmospheric research on the North Sea area as part of a field‐study on air‐sea exchange processes of particulate matter. The atmospheric loading for a number of elements was determined by EDXRF, yielding bulk concentrations for Mg, Al, Si, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Br and Sr. From these EDXRF data, deposition rates were derived and, based on a classical multivariate statistical approach, different aerosol sources were identified. Complementary to this work, EPXMA combined with automated image analysis was applied to individual size‐segregated aerosol particles to determine their inorganic composition, physical size and shape. Also, the first results of micro‐PIXE analyses on individual North Sea aerosol particles, particularly their large‐size fraction, are discussed and compared with the corresponding EPXMA results. In summary, such a joint approach with the use of different x‐ray emission techniques contributed to the resolution of the mixed structure of the lower North Sea troposphere and to the determination of the atmospheric supply of material to the North

ISSN:0049-8246    

DOI:10.1002/xrs.1300220410

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

年代:1993

数据来源: WILEY

摘要:

AbstractA description of the x‐ray microbeam spectrometer at Chalmers University of Technology is given with particular emphasis on the mapping and imaging features. The application of the microbeam technique to the analysis of bone specimens is also describe

ISSN:0049-8246    

DOI:10.1002/xrs.1300220411

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

年代:1993

数据来源: WILEY

摘要:

AbstractA number of examples of the use of a detailed Monte Carlo (MC) simulation program for EDXRF spectrometers is discussed. The MC code is employed to predict the complete spectral response of a polychromatic EDXRF spectrometer using different excitation conditions. With respect to quantification of steel samples in which significant enhancement and self‐absorption occur, the usefulness of the code in simulating spectra corresponding to calibration standards is demonstrated. An extension of the program that deals with simulating the interaction of polarized radiation with matter is used to estimate the analytical qualities of currently operating and future mono‐and polychromatic synchrotron radiation XRF spectromet

ISSN:0049-8246    

DOI:10.1002/xrs.1300220412

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

年代:1993

数据来源: WILEY