Radiation applications in art and archaeometry: X-ray fluorescence applications to archaeometry. Possibility of obtaining non-destructive quantitative analyses

Abstract

The possibility of obtaining quantitative XRF analysis in archaeometric applications is considered in the following cases: (i) Examinations of metallic objects with irregular surface: coins, for instance. (ii) Metallic objects with a natural or artificial patina on the surface. (iii) Glass or ceramic samples for which the problems for quantitative analysis rise from the non-detectability of matrix low Z elements. The fundamental parameter method for quantitative XRF analysis is based on a numerical procedure involving he relative values of XRF lines intensity. As a consequence it can be applied also to the experimental XRF spectra obtained for metallic objects if the correction for the irregular shape consists only in introducing a constant factor which does not affect the XRF intensity relative value. This is in fact possible in non-very-restrictive conditions for the experimental set up. The finenesses of coins with a superficial patina can be evaluated by resorting to the measurements of Rayleigh to Compton scattering intensity ratio at an incident energy higher than the one of characteristic X-ray. For glasses and ceramics the measurements of the Compton scattered intensity of the exciting radiation and the use of a proper scaling law make possible to evaluate the matrix absorption coefficients for all characteristic X-ray line energies.