Characterization of metal-complex-containing organic polymeric films by secondary ion mass spectrometry

The SIMS technique has been successfully applied as an analytical tool for the chemical and spatial analysis of metal-complex-doped polymeric films. The polymeric matrix was chlorosulfonated polystyrene (∼ 1000 Å thick) cast onto a smooth platinum substrate, and following subsequent incorporation of metal complexes containing Ru, Re, or Zn by chemical binding, the SIMS technique was found to be chemically selective and sensitive to the Ru, Re, and Zn sites in the polymeric films. Qualitative assays of the films using secondary ion mass spectra were carried out with relative ease, but determinations of the spatial distribution of metal sites throughout the films require highly controlled sample preparation. The results of a series of studies on polymeric films containing various levels of the Ru complex showed that signals for Ru⁺ are influenced by local variations in ion yield, i.e., ion yield transients near the polymeric surface and at the polymer/platinum interface. A normalization procedure based on comparisons of Ru⁺ to O⁺ secondary ion intensities reduces the influence of such artifacts in the analysis of the concentration depth profiles of the complexes within the polymeric films.