Hjm Hans Heijligers

PROZA96: An improved matrix correction program for electron probe microanalysis, based on a double Gaussian phi(rz) approach

A new bulk matrix correction program for quantitative electron probe microanalysis based on a double Gaussian φ(ρz) approach is presented. The independent input parameters for this new model are α (decay rate in the righthand Gaussian), surface ionization φ(0), peak position (ρz m ) and integral of φ(ρz) (FI). The Gaussian exponent in the left-hand branch (β) is calculated through an iterative procedure. The resulting program is completely modular in structure, which means that all vital independent input parameters can freely be changed without disrupting the mathematical functioning of the model. The increased flexibility of this new model (PROZA96) leads to superior performance over its predecessor (PROZA), especially for the analysis of ultra-light elements.

Nonconductive Specimens in the Electron Probe Microanalyzer—A Hitherto Poorly Discussed Problem

Electron probe microanalysis and scanning electron microscopy of nonconducting specimens usually present the operator with problems. Many of these problems are related to the image quality: nonconducting specimens usually yield highly unstable images, often characterized by extremely bright areas at locations with the worst electrical conductivity and sudden shifts in the image with respect to the specimen from time to time. The bright areas in the image are the result of an excessive production of secondary electrons which in turn leads to a very poor resolution of surface details by the production of a halo.

Experimental determination of the surface ionisation in electron probe microanalysis

An experimental procedure is described for measuring the surface ionisation values φ(o) using thin-film measurements on a wide variety of substrates. The φ(o) values are determined by establishing the ratios of the film element X-ray intensities emitted from supported and unsupported thin films for a number of different film thicknesses and extrapolating towards a film thickness approaching zero. A number of 180 φ(o) data each for Al Kα and Pd La X-radiations between 4 and 30 kV, on substrates ranging from beryllium up to bismuth, have been collected in this way. The purpose of this work was to provide a systematic database on which a variety of existing expressions for φ(o) could be tested. In the final assessment procedure, in which we also included 108 data from literature, we compared the performance of the various expressions from literature for φ(o), as well as a newly developed one of our own. Our final conclusion is that there is little to be chosen between the three highest-ranking expressions.

Wavelength‐ and energy‐dispersive Electron Probe Microanalysis (EPMA) measurements with non‐perpendicular incidence of the electron beam

A database of 416 wavelength‐ and energy‐dispersive EPMA measurements on tilted specimens of NiAl, TiO2 and Ti3Al is presented. The analyses were performed between 10 and 30 kV and the tilt angles were varied between 0° and 60° in seven steps. The necessary hardware modifications for the specimen holder are discussed, as well as the various focusing techniques used in the measurements. A comparison between the experimental data, the calculations of our proza96t program and the results of Monte Carlo simulations shows that up to 50° tilt the predictions of our software are more than satisfactory. At larger tilt angles some deviations become noticeable. The Monte Carlo simulations appear to produce deviations at a somewhat earlier stage already, for reasons as yet unknown.