The analysis of tiiin films by SSMS - A more detailed discharge model and recent experiments

Recent advances in analytical spark source mass spectrometry

Spark source mass spectrometry is an established technique for the chemical analysis of trace and minor inorganic constituents in many types of material. Its merits are its inherent high sensitivity with detection limits down to a few nanograms per gram and an extremely wide elemental coverage, i.e. essentially all the elements present in the sample. Drawbacks that explain its lesser popularity compared with other techniques result from (1) the complexity and cost of the apparatus, (2) the time-consuming operation when detection is performed with an ion emulsion, and (3) inaccuracies inherent in ion formation and the measurement process. A review will be given of the basic theory, the instrumentation and a few representative applications. Special reference will be made to recent advances in methodology (e.g. the development of multi-element isotope dilution) and instrumentation: the development of the understanding of the r.f. spark ion formation process, alternative mechanisms for ionization, and the exploitation of ion detectors other than the photographic plate (electrical detection with electron multipliers and position-sensitive detectors).

Nonoptical characterization of optical coatings

Besides the theoretical design of optical interference coatings, the knowledge of their nonoptical properties like chemical composition, structural features, mechanical peculiarities, and environmental stability is often a basic condition for their industrial production. After some remarks on specifications and standards relevant for optical coatings this paper gives a review on various possibilities for nonoptical characterization of optical coatings. Those methods of surface analysis, depth profiling, and electron microscopy available to and widely used by a major coating manufacturer-like Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM), energy dispersive (ED) and wavelength dispersive (WD) electron probe microanalysis (EPMA)-are pointed out in more detail and illustrated with examples from daily practice. Other characterization methods, which are less common but very interesting, are also briefly reviewed.