DETERMINATION OF SURFACE COMPOSITION OF BRONZE MIRRORS BY ENERGY DISPERSIVE X-RAY FLUORESCENCE ANALYSIS.

The excitation source used for the present study is 241Am of 500 mCi, and molybdenum metal is used as second target. The intensities of Ka of copper, La+β of tin and Lβ of lead coming from the object are determined, and then its composition can be calculated by experience coefficient method. Six bronze mirrors are determined for contents of copper, tin and lead. The results show that the ratio of Sn/Cu is lower with the increase of depth within 100μm but the ratio of Pb/Cu does not obviously vary in this range. These two ratios become constant when the detection depth is more than 100μm. It can be expected that the surface composition of bronze mirror at certain depth will be able to represent the composition of mirror body when the X-ray fluorescence analysis technique is used.