Isotopic ratio measurements with laser ablation coupled to mass quadrupole spectrometry

Abstract

Physical analyses by laser ablation coupled to a mass quadrupole spectrometry technique on different metallic samples (standards of calibration, minerals and old bronze coins) have been undertaken. Laser ablation induces controllable surface layer removal in high vacuum. Contemporary mass spectrometry analyzes mass elements, mass compounds and isotopic relative content. A comparison between the experimental isotopic ratios and the expected values from the natural abundance is presented. The differences are discussed in terms of the technique's limitations and of the fluctuations due to geographic areas of the material's provenience. Measurements of stable isotopic ratios in copper, lead and tin have been performed in old Egyptian coins. Results confirm that the minerals contained in the coins come from different geographical locations and mines. Results are presented and discussed from the point of view of the physical technique, geological areas and archaeological aspects of peculiar investigated samples.