Portable X-ray diffractometer equipped with XRF for archaeometry

Abstract

A portable X-ray diffractometer equipped with an X-ray fluorescence spectrometer was improved so as to get a diffraction pattern and a fluorescence spectrum simultaneously in air from one and the same small area on a specimen. Here, diffraction experiments were performed in two modes, i.e. an angle rotation mode and an energy dispersive mode. In the latter a diffraction pattern and a fluorescence spectrum were simultaneously recorded in a short time, 100 s or less, on one display. The diffractometer was tested in the field to confirm its performance. Targets chosen for this purpose were a bronze mirror from the Eastern Han Dynasty (25–220), and a stupa and its pedestal which are part of the painted statue of “Tamonten holding a stupa” from the Heian Period (794–1192), enshrined in the Engyouji temple founded in 996. The bronze mirror was identified as a product of the Han Dynasty from its chemical composition and the existence of the δ phase in the Cu–Sn alloy. The stupa and its pedestal were decorated with gold powder and gold leaf, respectively. From the XRF data of the pedestal, the underlying layer of gold leaf seems to have been painted with emerald green.