IMPACT OF MASS-SPECTROMETRY IN SURFACE-ANALYSIS

The surface scientist has a wide range of sophisticated techniques available to study the state of surfaces and molecules adsorbed thereon. On single crystals the surface geometry and structural and electronic state of the surface and simple adsorbates can be probed precisely. On less ideal surfaces, many of the techniques are very difficult to apply. Amongst the armoury of surface science techniques, only two have produced significant fruit in the study of chemically complex materials: X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SSIMS). Although XPS has been, and continues to be, very important as the most widely used method of surface analysis, in many applications of current interest SSIMS is proving to have tremendous potential and could develop into the technique of choice for a vast range of problems. Chief amongst its strengths is its emerging ability to provide chemical structure data in the form of the cluster or polyatomic ions which are observed. The emergence of SSIMS as a true surface mass spectrometric technique for the analysis of complex materials is reviewed and the following aspects are demonstrated: SSIMS is basically a soft ionization technique where the spectra are related to the surface chemical structure; organic and other insulating materials can be analysed easily; and time-of-flight analysers ace the analysers of choice for most SSIMS analyses.