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A new user end-station is under construction at the ESRF with collaboration between the Micro-Fluorescence, Imaging and Diffraction beamline (ID22) and the Micro and Trace Analysis Center (MITAC) of the University of Antwerp. The new end-station is dedicated to quantitative micro-fluorescence measurements. The analytical characteristics (degree of polarization of the incoming beam, absolute and relative detection limits) of the new set-up were investigated during preliminary experiments by using a temporary experimental set-up. Copyright © 2001 John Wiley & Sons, Ltd.

The various application possibilities of microscopic x-ray fluorescence and associated methods for the characterization and provenance analysis of objects and materials of cultural heritage value are discussed by means of a number of case studies. They include the trace analysis of historic glass, the analysis of corroded coins and statues in bronze and silver and the study of inks on historical documents. These studies are conducted by means of micro-XRF instruments installed at synchrotron beamlines and by means of laboratory equipment, some of which is easily transportable to the museum or archaeological site where the objects of interest are located. Copyright © 2000 John Wiley & Sons, Ltd.

The functionality of the computer package AXIL (Analysis of X-ray spectra by Iterative Least squares), suitable for the evaluation of energy-dispersive X-ray spectra, has been extended in a number of ways. First, a background modelling algorithm, based on the use of mutually orthogonal polynomials was introduced to replace the linear or exponential polynomials employed previously. Second, the Gaussian photopeak model employed in previous versions of the program was extended to include the non-Gaussian parts of the characteristic peaks and related background contributions. Both innovations are shown to improve the performance of the spectrum evaluation procedure. Third, the user-friendliness of the evaluation program was enhanced (a) by allowing a PC plug-in MCA card to be directly controlled from within the program and (b) by extending the command-interface to allow for repeated execution of series of commands by means of control loops. A brief description of these changes is given; as an application, the accurate evaluation of micro-XRF images is discussed.

Information included in auxiliary signals, i,e. incoherently and coherently scattered signals and transmitted beam intensities in x-ray fluorescence analysis (XRF), a selected channel in the scattered white synchrotron radiation and in the contents of selected hremsstrahlung channels in electron microprobe analysis (EMPA), can be extracted and exploited to complete the results of analyses. Such additional information is much more detailed when the devices are operating in the microprobe mode; however, this is not a necessary condition. The theoretical basis for the use of the auxiliary signals, in the sense proposed in this paper, is discussed. In situations where the main component is of essentially constant chemical composition but with variable density through the sample (wood of living trees, petrified wood, stalactites, coral structures-in general natural periodic structures) or with inclusions inside, the application of two kind of signals is preferable in XRF: the transmitted and scattered signal. For light organic matrices (cellulose, plastics), the information included in the Rayleigh or Compton signal is reversed in relation to the information from the transmission signals. The selected hremsstrahlung signal or the signal from the secondary electron spectrum can serve the same purpose if EMPA analysis is performed. In general, these signals provide auxiliary knowledge about the density of objects. An especially interesting situation is when the object is a chemical negative of the original, such as the distribution of silica in some kinds of petrilied wood with respect to the distribution of the cellulose in the original wood. Many original results of analyses are shown. Intercomparisons of the transmission images with the reversed scattered scans in light matrices are still scarce, while the observation of bremsstrahlung or secondary electron scans (in EMPA) and their scattered or transmission analogues (in XRF) for objects and their chemical negatives is demonstrated for the first time. Comprehensive results of the analyses of petrified wood and stalactites (EMPA and XRF) are presented.

The combined use of principal component analysis (PCA) and K-means clustering (KMC) for the segmentation and (semi-)quantitative calibration of multivariate μ-XRF data sets is proposed and evaluated. The usefulness of the method is compared with that of using PCA or KMC separately by discussing image sets derived from geological and archeometric samples.