摘要:

AbstractUsing a 30‐cm bent crystal transmission spectrograph in Canchois geometry, the x‐ray K‐absorption edges of cobalt and nickel were recorded using both pure metal foils and electrodeposited films on a copper foil substrate. For nickel, electrodeposition was also done in the presence of an externally applied magnetic field of 52 G in order to obtain a magnetized film. This film revealed only a slightly different EXAFS spectrum. A chemically plated amorphous film of nickel containing 8% phosphorus was also studied. All the EXAFS were subjected to Fourier transform analysis, which revealed how the nearest neighbouring atom distances change in different films compared with those in pure metal

ISSN:0049-8246    

DOI:10.1002/xrs.1300190602

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe parameters ϕ0and γ0of the Gaussian model for the depth distribution of characteristic x‐ray production ϕ(ρz) were evaluated using an analytical expression for the energy distribution of backscatrered electrons. The expressions obtained were compared with those which do not take into account this distribution. A test of the usefulness of both models was performed for microanalysis correc

ISSN:0049-8246    

DOI:10.1002/xrs.1300190603

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe analytical expression for the total backscattering coefficient of a double‐layer solid system was obtained by the Niedrig combined model. Calculated results are given for the backscattering of a bulk target, free film and film on substrate at normal incidence, and also for a double‐layer structure at oblique incidence. These results are compared with experimental data and Monte Carlo calculations taken from the literat

ISSN:0049-8246    

DOI:10.1002/xrs.1300190604

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

年代:1990

数据来源: WILEY

摘要:

AbstractSub‐micron spheres of pure materials prepared by electrohydrodynamic atomization were used to determine experimentally the x‐ray distribution function, ϕ(ρz), for spheres using a dedicated HB501 scanning transmission electron microscope at 100 keV. The materials chosen were W, Pd, Ni, V and Al thin spheres. ϕ(ρz) was measured experimentally using a tracer technique. The thin film tracers used were Ir, Ag, Cr, Cu and SiO2, respectively. ϕ(ρz) for the above materials was also calculated using a Monte Carlo trajectory simulation modeled for the tracer technique. The experimental tracer ϕ(ρz) results show a pronounced scatter, especially for large‐diameter spheres. Local variations in the tracer film thicknesses appear to be the reason for such scatter. The trends in the experimental and Monte Carlo results, however, are simple and show a strong dependence on the atomic number of the target material. A general expression for ϕ(ρz) for thin spheres is presented which fits the experimental tracer results. The Monte Carlo results agree well with the fitted data for elements of low atomic number and/or small‐size spheres. For elements of higher atomic number (Pd and W), however, the Monte Carlo ϕ(ρz) curves peak too early with mass thickness. This problem may be due to inadequacies of the scattering cross‐section models

ISSN:0049-8246    

DOI:10.1002/xrs.1300190605

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

年代:1990

数据来源: WILEY

摘要:

AbstractA rapid method for the simultaneous determination of potassium and calcium in milk powder by energy‐dispersive x‐ray fluorescence (EDXRF) spectrometry was developed. The measurement system consists of a Si(Li) detector, an x‐ray tube coupled with titanium as a secondary target, a DEC‐350 computer and a nonlinear fitting least‐squares program. The methods of calibration and standard preparation are discussed. Milk powder was analysed as pressed pellets using counting times of 100 s. Concentrations were determined by a standard calibration graph method using synthetic standards. The minimum detection limits are 0.011% and 0.007% for potassium and calcium, respectively. The accuracy was ascertained by analysing standard reference materials from the International Atomic Energy Agency. Good agreement was found between the certified and measured values. Potential applications of this method are

ISSN:0049-8246    

DOI:10.1002/xrs.1300190606

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

年代:1990

数据来源: WILEY

摘要:

AbstractAll currently known changes in the values of the α coefficients in the Lachance‐Traill equation occurring under the influence of different factors are considered. These factors include the change in composition in connection with the enhancement phenomenon, the change in radious of grains (or lamellae) in a non‐homogeneous environment and the change of angle of the analytical surface slope relative to the ideal flat surface. Changes in the α coefficients are found to be always of hyperbolic character. A new version of the Lachance‐Traill equation has been

ISSN:0049-8246    

DOI:10.1002/xrs.1300190607

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

年代:1990

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300190608

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

年代:1990

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300190609

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

年代:1990

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300190601

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

年代:1990

数据来源: WILEY