Surface enhanced characterization of complex stratified materials using synchrotron radiation at grazing incidence excitation conditions

A. KARYDAS; JUAN JOSÉ LEANI; A. MIGLIORI; R. PADILLA-ALVAREZ; M. BOGOVAC; R. KAISER; C. CALIRI; P. ROMANO

Catania

Congreso; TECHNART 2015 − Non-destructive and Microanalytical Techniques in Art and Cultural Heritage.; 2015

Laboratori Nazionali del Sud

The requirement for depth sensitive non-destructive analysis is very often imposed when archaeological and historical materials with stratified structure need to be characterized. These materials might be the intentional result of a particular manufactured process or simply the consequence of the alteration of the original surface due to surface enrichment phenomena or environmental factors (exposure in burial conditions or/and in atmosphere). Analytical methodologies such as confocal X-ray microscopy (CXM) have been developed and applied offering depth resolved elemental and speciation analysis up to few hundreds micrometers depending on the nature of the investigated material [1]. However, the depth sensitivity of CXM is mainly hampered by the technological restraint imposed by the X-ray focusing elements performance which can achieve an optimum spatial resolution close to 10 um. Thus, the quantitative characterization of surface layers with a thickness of very few tens of micrometers remains a challenging task, in particular when the same elements are present in different layers.Angular resolved elemental and speciation analysis using synchrotron radiation at grazing incidence conditions is a promising analytical methodology for investigating with enhanced depth resolution surface layers of few micrometers thickness. The IAEA has recently developed a multipurpose end-station facility at the XRF beamline of Elettra Sincrotrone Trieste that offers the required degrees of freedom for scanning measurements and precise positioning of the sample surface at different incident angles [2]. The present work explores the new possibilities for surface characterization of cultural heritage materials that the new experimental facility could offer by means of Monte Carlo simulations using the XMI-MSIM package [3]. Different examples of samples, commonly encountered in the archaeometrical and conservation research, including decorated and glazed ceramics, gilded gold alloys and silver coins, are presented and discussed.