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An Experimental Evaluation of the Atomic Number Effect

Published online by Cambridge University Press:  06 March 2019

L. Parobek
Affiliation:
Faculty of Engineering Science and Centre for Interdisciplinary Studies in Chemical Physics, The University of Western Ontario, London, Canada
J. D. Brown
Affiliation:
Faculty of Engineering Science and Centre for Interdisciplinary Studies in Chemical Physics, The University of Western Ontario, London, Canada
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Abstract

A method for measuring the atomic number effect is developed using a sandwich sample technique. The depth distributions of x-ray production, ϕ(ρz) curves, have been measured for a zinc tracer in aluminum, copper, silver and gold matrices at 30, 25, 20 and 15 keV. The ϕ(ρz) curves were measured using a Cambridge Microscan 5 in which the electron beam is normal to the sample surface and the x-ray take-off angle is 75°.

Samples of the low concentrations of copper (∼1 Weight %) in aluminum, nickel, silver and gold were prepared. For each alloy system (for example, Cu - Al), three different concentrations of copper were prepared. The intensity ratios from the sample to the pure element (standard) for each system have been plotted against concentration. At such low concentrations of copper the relation between this ratio and concentration is linear. The slopes of the curves have been compared to the equivalent factors obtained as ratios of the area under F(ρz) curves for aluminum, silver and gold to the area under F(ρz) curve for copper, respectively. The F(ρz) curves are obtained from ϕ(ρz) curves; F(ρz) = ϕ(ρz) exp(-μρz csc ψ) where μ is mass absorption coefficient.

Comparisons are made between these experimental data and the current methods of calculating the atomic number effect.

Type
Research Article
Copyright
Copyright © International Centre for Diffraction Data 1973

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