ISSN:0049-8246    

DOI:10.1002/xrs.1300150102

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

年代:1986

数据来源: WILEY

摘要:

AbstractA set of particulate monolayer samples with a δ‐distribution of particle sizes has been produced on Lawsan membrane filters by means of a cascade impactor. The accuracy of a proposed equation for characteristic x‐ray intensity from particulate monolayers of various chemical and granular compositions has been experimentally confirmed. x‐ray spectra of Fe and PbTiO3powders have been examined following excitation by monochromatic p

ISSN:0049-8246    

DOI:10.1002/xrs.1300150103

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

年代:1986

数据来源: WILEY

摘要:

AbstractTrace amounts of heavy metals were preconcentrated on discs of polyurethane (PU) foam loaded with ammonium diethyldithiocarbamate (DDTC), to increase the sensitivity of XRF. Since the diameter of the cavities in the open‐cell PU foams reaches 30–300 μm, considerable heterogeneity effects might occur, which could reduce the accuracy of the method. The possible systematic error introduced by considering the sample to be homogeneous is calculated using the Berryet al.model. The calculations show that the underestimation of the absorption correction factor when considering the sample as being homogeneous is less than 2% for high‐Z elements when the sample thickness is at least 2 mm. The detection limits are also around the minima for this thi

ISSN:0049-8246    

DOI:10.1002/xrs.1300150104

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

年代:1986

数据来源: WILEY

摘要:

AbstractA comparison of four methods for the determination of barium, lanthanum, cerium and neodymium in lateritic materials from Brazil is presented. Three of the methods were based on x‐ray fluorescence (XRF) spectroscopy: two by radioisotope excitation (Co‐57 and Am‐241) and one by secondary target XRF (a molybdenum target with a tungsten anode). The other method was based on neutron activation analysis employing both a Ge(Li) coaxial detector and a high‐purity germanium detector.The results from these four methods were similar for lanthanum, cerium and neodymium, but for barium at low concentrations (<500 ppm) the neutron activation and the secondary target XRF methods were not suitable. Data on the precision and accuracy of these methods using a series of standard reference rocks are given. The advantages and limitations of each of these methods with respect to the analysis of lateritic materials are di

ISSN:0049-8246    

DOI:10.1002/xrs.1300150105

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe complexes of Co and Cu with 2‐thiopyrrole‐1,2‐dicarboximide andN‐carbamoylpyrrole‐2‐thiocarboxyamide were studied by recording the x‐ray K‐absorption edge and the extended structure. The nature of the metal to ligand chemical bond has been interpreted in terms of the effective

ISSN:0049-8246    

DOI:10.1002/xrs.1300150106

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

年代:1986

数据来源: WILEY

摘要:

AbstractAn increase of an order of magnitude in the precision of the balanced filters method is achieved by using a low‐power x‐ray tube and measuring the ionization current, without increasing the measurement time. A simultaneous change of excitation and detection is essential: the measurement of the ionization current makes possible a dead‐time free detection of the high intensities excited by the x‐ray tube, and leads to a decrease in the statistical error. The standard deviations obtained with a portable analyser utilizing this method in the determination of the Cr and Mn contents of low‐alloy steels in the concentration range 0–1.5% are 0.02 and 0.03%, r

ISSN:0049-8246    

DOI:10.1002/xrs.1300150107

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

年代:1986

数据来源: WILEY

摘要:

AbstractAnalytical approximations for mass attenuation coefficients have been derived in an energy range adapted to x‐ray spectrometric analysis (2–40 keV). Approximation parameters have been calculated using a recent compilation of photon interaction cross‐sec

ISSN:0049-8246    

DOI:10.1002/xrs.1300150108

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

年代:1986

数据来源: WILEY

摘要:

AbstractA new empirical mathematical method for inter‐element effect corrections in XRF analysis is presented. It is based on a special theoretical description of XRF phenomena called OMX (operator model of x‐ray fluorescence), presuming a discrete layer model of the sample structure and using mathematical operators to describe the interaction between sample layers and exciting radiation. The operators formed generally as spectral distributions may be simplified into the matrix form for practical application. The effectiveness of the proposed method was verified experimentally by analysing samples of glass and glass raw materi

ISSN:0049-8246    

DOI:10.1002/xrs.1300150109

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

年代:1986

数据来源: WILEY

摘要:

AbstractEnergy‐dispersive x‐ray fluorescence (EDXRF) analysis of manganese compounds has been carried out. A significant dependence of the Mn Kα and Kβ x‐ray yields per incident photon and of the Kβ/Kα ratio on the valence state of manganese in these compounds was observed. The measurement of attenuation coefficients of these compounds, which are used in absorption corrections in XRF analysis, also showed similar effects. These results imply that the EDXRF elemental analysis results have inherent inaccuracies of the ord

ISSN:0049-8246    

DOI:10.1002/xrs.1300150110

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

年代:1986

数据来源: WILEY

摘要:

AbstractRapid and high‐quality major and trace element data can be obtained by automated x‐ray fluorescence (XRF) analysis of pressed rock powder pellets. The sample preparation procedure is simple, quick and can be done well with minimal supervision. Analysis of the rock pellet for 22 elements requires about 1 h of machine time. The system is calibrated by use of multiple international rock standards and employs a ratio standard for all measurements. Most calibrations are simple linear fits between intensity and concentration. The precision of the major element results are generally better than ±1% of the amount determined, whereas the trace element precisions are generally less than 5%, except when the value determined is close to the detection limit. Accuracies are comparable to those of other published XRF rock analysis proced

ISSN:0049-8246    

DOI:10.1002/xrs.1300150111

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

年代:1986

数据来源: WILEY