QUANTIFICATION OF SULFUR IN COPPER BY SECONDARY-ION MASS-SPECTROMETRY(SIMS)

Secondary Ion Mass Spectrometry (SIMS) measurements were performed for oxygen-free copper-base alloys with various sulfur concentrations fro m 0.02 to 14.0 mass ppm, and the influence of molecular ions O-16(2)- on the analysis of sulfur was studied, The secondary ion yield ratios of S-34(-) to S-32(-) were nearly the same as their isotopic abundance ratio in the analyzed sulfur concentration range. The secondary ion y ield ratio of O-16(2)- to O-16(-) decided by the high mass resolution analyses was 1.3 +/- 0.5 x 10(-3), which suggested that only 3% of the secondary ions of the 3Zm/e signal, where rn is the mass number and e is the electric charge, would come from O-16(2)- ions in the most dil ute alloy case. From these facts, the interference by O-16(2)- ions ca n be neglected as far as oxygen-free copper concerns. The determinatio n limit on the measurement of S-32(-) ions was less than 0.02 mass ppm , and that on the measurement of S-14(-) ions was 0.02 mass ppm with t he normal resolution analyses.