Synchrotron x-ray fluorescence on ancient gold coins: how trace elements can give insight into the Roman Empire

X-Rays are a non-destructive, element specific probe of great potential for cultural heritage. Furthermore, synchrotron radiation sources provide high intensity leading to extraordinary sensitivity. These capabilities were exploited for studying four ancient gold coins dating back to the IV and V century A.D.. Combining the complementary information obtained by X-Ray Fluorescence and Photoemission Spectroscopy, we determined the chemical composition of the coins and we assess the speciation of the chemical contaminants providing information about historical situation of the minting period of the specimens and the metallurgic knowledge available at the time.