ISSN:
0049-8246
Schlagwort(e):
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Physik
Notizen:
Sub-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 used in the analysis.
Zusätzliches Material:
12 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/xrs.1300190605
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