F-12 Glancing Incidence XRF for the Analysis of Early Chinese Bronze Mirrors

Abstract

The composition of ancient Chinese bronze mirrors has been determined by X-ray fluorescence measurements. The mirrors were archived to be from either 200 BCE-200 CE and from approximately the 800 CE period. Glancing incidence X-Ray excitation proofed highly useful for obtaining the elemental composition from the fluorescence measurements. Measurements of the tin L/K X-ray fluorescence ratio as a function of the glancing incidence angle showed that this ratio became independent of the glancing angle for angles less than 5°. Glancing X-ray fluorescence measurements made at 2° were then calibrated to known standards to give highly accurate compositions for major elements in the Chinese bronze mirrors. X-Ray diffraction measurements were used to test for composition segregation or crystal structure changes near the surface of the mirrors. The X-ray diffraction angles were found to be independent of the glancing angle indicating that surface composition segregation was not observed. Changing relative intensities of the observed diffraction reflections indicated that the crystal texturing changed near the surface.