Direct Determination Method for Homogeneous Solid Samples in X-Ray Fluorescence Analysis

Abstract

The concept and theory of a direct determination method (DD method) and the procedure for carrying out the DD method for homogeneous solid samples are presented. The theory presented is general for homogeneous solid samples. A thin‐film sample, single layer on a substrate, coating multi‐layer on a substrate and bulk sample (including pieces, powder and fragments) can be regarded as special cases of the application of the theory. A practical application to 12 commercial iron‐based spray powder samples was studied and experimental data from literature were used to calculate the composition and thickness of thin‐film samples with the DD method. The analytical expressions of intensities of de Boer and Brouwer were modified and applied to the DD method. Two independent computer programs, written in BASIC, were used to calculate the numerical values for bulk and thin‐film samples. It is reasonable to expect that a common computer program for the DD method will soon be developed and will be applied to all sorts of homogeneous solid samples without specific sample preparation.

Quantitative X-ray fluorescence analysis of samples of less than ‘infinite thickness’: Difficulties and possibilities

“…(1) includes absorption and enhancement effects between all elements within thin layer and cannot be applied for the analysis of multilayers or single coating layer on a bulk substrate which can enhance atoms in the coating. Previously published comprehensive algorithms dedicated to analysis of multiple layer films [18,25,26] assume such effects as primary fluorescence, secondary fluorescence within the same layer, secondary enhancement between different layers (two cases: enhancing element underneath the analyte layer and enhancing element on top of the analyte layer) and also secondary enhancement from the bulk substrate. Analysis of multiple layer films can be seriously hampered if one element of unknown concentration is present in more than one layer.…”

Non-destructive analysis of small irregularly shaped homogenous samples by X-ray fluorescence spectrometry

“…If the calibration procedure is carried out for two different element lines i and k with standard samples having the same surface conditions, area and position in the sample holder, one can calculate a relative instrumental calibration factor in the same way as Wang [1] does:…”

“…These calibrations rely on constant measuring geometry and surface conditions between sample and calibration standards. Wang [1] published a method that does not pose requirements regarding shape and surface conditions to the unknown samples. The unknown samples should only be homogeneous and should fit in the sample holder.…”