SIMS analysis of lead isotope composition in ancient Chinese metallic artefacts

An attempt on the use of secondary ion mass spectroscopy (SIMS) in studying ancient Chinese bronze is reported with an evaluation of the suitability o f SIMS for the provenance study of ancient bronze objects. The advantage of using SIMS in the study of the lead isotope ratio is the high sensitivity that enables the examination of small fragments of valuable relies that are often difficult to collect. The application of SIMS in this direction wide ns the sampling area, which is limited by the use of thermal ionization mas s spectroscopy (TIMS). The focus of the study has been placed on the precis ion of SIMS when compared to TIMS and the effect of sample matrices on the precision. Samples of Chinese bronze artefacts and a standard lead sample ( SRM 981) were tested for their lead isotope ratios using both SIMS and TIMS . A comparison of the data obtained using the two techniques showed that SI MS results have a relatively large standard deviation, which was attributed to the non-uniformity of the ancient samples and the single-isotope detect ion system of the SIMS set-up used, Matrix effects were found to be small a mong bronze samples of different compositions. Non-conducting samples can a lso be analysed when a specimen isolation technique is employed. Although S IMS gave higher uncertainties than TIMS, the SIMS technique can be applied easily to differentiate the high radiogenic lead in Shang bronze artefacts from common lead. Copyright (C) 2000 John Wiley & Sons, Ltd.