A couple of years before my retirement from Analytical Chemistry at the University of Twente I entered the field of X-Ray Fluorescence Analysis (XRF). At that time quantitative analyses were carried out in our laboratory mainly by using dilution techniques to obtain straight calibration lines over limited concentration ranges for the intensity versus concentration relationship.
A literature study soon revealed that in the last 40 years quantitative XRF has seen the development of numerous methods based on empirical and fundamental equations for the relationship between measured fluorescence intensities ans sample concentrations. Even so, much debate is still going on [1,2] about the merits of the various approaches. So called fundamental parameter methods are prevalent nowadays.
We have developed a set of computer programs that can be used to make a choice from various existing methods and added some new elements in the iteration procedures for obtaining sample compositions from measured intensities. [3-5].
Although I am retired now, I still maintain these programs and you can freely download them from this site under the GNU General Public License of the Free Software Foundation.
M.Bos - Enschede April 26th 2003.
In its standard form XRFCOMBI cannot be used for spectrometers with polycapillary optics. A separate version (POLYXRFCOMBI) has now been developed that uses a tabulated excitation spectrum instead of Pella's algortihm to generate it. This allows the user to correct the tube spectrum for the wavelength dependent transmission of the polycapillary optics, or to use a measured excitation spectrum.
POLYXRFCOMBI can be downloaded from this link:
polyxrfcombi.zip
Instructions for its use can be found in the subdirectory docs after unzipping the archive.
M.Bos - Enschede, December 20th 2008
In March 2004 the program xrfcombi was extended with corrections for the contribution of second order processes comprising one scattering event and one photoelectric absorption based on the work of Tirao and Stutz [6]. Included are (1) Rayleigh scattering of the tube radiation followed by photoelectric absorption giving rise to the measured fluorescence line, (2) Compton scattering of the tube radiation followed by photoelectric absorption given rise to the measured fluorescence line and (3) Rayleigh scattering of the fluorescence radiation towards the detector. Rayleigh scattering is calculated with data from the RTAB database of L.Kissel. Compton scattering is handled by an equation based on the Thomas-Fermi model.
M.Bos - Enschede March 16th 2004
The xrfcombi program features functions for
Here are the files:
xrfmul is a barebones commandline program that can be used to calculate compositions and thicknesses of the layers of a multilayer sample from the relative intensities of its elements and the qualitative composition of the sample for all its layers.
The files are now included in the xrfcombi package. The executable is in the ~/combiscat/bin directory.
The program xrfmul uses input files to get the pertinent data, the results are presented on screen (stout), but can be redirected to a file if wanted.
The program simmul can be used to calculate fluorescence intensities from multilayer samples. It is used from the (dos) commandline and uses input files to specify the multilayer structure, the layer compositions and theicknesses and the names of the fluorescence lines of which the intensities should be calculated. The results are presented on the screen (stdout) but can be redirected to an output file.
The files are now included in the xrfcombi.tgz package. The executable can be found in ~/combiscat/bin.