ION MICROPROBE TRACE-ELEMENT ANALYSIS OF SILICATES - MEASUREMENT OF MULTIELEMENT GLASSES

At present, ion microprobe determination of trace elements in silicates is dependent upon the availability of homogeneous well-characterised standards of similar major-element composition to the unknown. Our ability to predict yields where no standard is available and finally move towards standardless quantitative analysis requires modelling of ion yield behaviour. A table of ion yield data for low- and high-energy ions of > 60 elements measured in the NBS 610 standard glass is presented, and includes ion yields for doubly charged and oxide ions. The variations in ion yield with atomic number give relatively smooth patterns especially for high-energy ion yields. Notably, a periodic relationship exists in ion yield behaviour. Variations which occur under different analytical (beam density?) conditions are related to the mass of the ion. Corrections can be applied to remove these effects. Unfortunately Si+, while being the most obvious element to use for normalisation in silicates to remove operator/laboratory artifacts, is one of the most sensitive elements to changes in analytical conditions. © 1990.