MATRIX EFFECTS ON THE RELATIVE SENSITIVITY FACTORS MEASURED BY LASER MICROPROBE MASS-SPECTROMETRY

Analyses using a LIMA-2A laser microprobe of Fe3Al 3 at.% X and metal oxide samples are reported. The results are compared to the local ther modynamic equilibrium (LTE) model in which the relative sensitivity fa ctor (RSF) is predicted to depend on the ionisation potential. The RSF depended on the ionisation energy for metals in Fe3Al 3 at.% X as exp ected, but not for non-metals. The agreement for non-metals was enhanc ed if they were plotted at a corrected ionisation energy given by the ionisation energy of the element in the same row of the periodic table with the electronic configuration (noble gas+s2+one electron) i.e. fo r silicon the corrected ionisation energy is that of aluminium. A poss ible explanation of this is that the metallic sea of electrons in the Fe3Al has altered the electronic state of the dopant element X if X is not itself a metal. Analyses on metal oxides with differing oxidation states showed that the RSF depended on the electronic state of the me tal. Thus lending weight to the hypothesis that the production of ions from a sample depends on the electronic structure of the element in t he matrix rather than in isolated form.