The Use of Focussed X-Ray Beams for Non-Destructive Characterization of Historical Materials

Abstract

In this work, the use of X-ray micro beams for non-destructive characterization of historical, archaeological and artistic materials will be described. Only the use of X-ray micro beams generated in dedicated beam lines of synchrotron storage will be discussed. Attention will be devoted to two methods of analysis:.t-XRF (X-ray fluorescence analysis) [1] and µ-XANES (X-ray absorption near-edge spectroscopy) [2]. The former method allows quantitative trace-level micro-analysis of a variety of materials while the second permits to extract information on the valence of (trace) metals in these materials. µ-XRF may be practised at synchrotron beam lines, where the polarized nature of the radiation can be used advantageously for lowering the scatter background level in the energy-dispersive X-ray spectra, leading to improved detection limits. When suitable focussing devices are employed,.t-XRF measurements can also be performed by means of compact and/or portable laboratory equipment. The latter kind of instrumentation allows for in-situ measurements (for example in a gallery, a museum etc.). In view of the requirement to employ highly monochromatic radiation, tXANES is a method that only can be employed at synchrotron facilities. The use of these methods for characterization of historical glass fragments and handwritten paper documents is briefly described.