Emission of Microparticles from Automotive Sources—X‐ray Photoelectron Spectroscopy in Environmental Analysis

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Abstract
In the last fifteen years the necessity for efficient environmental protection has become generally accepted. However, before practical measures can be taken, a comprehensive assessment of the present environmental situation should be made, taking into consideration the risks involved in as well as the positive effects of any planned environmental changes—whether natural or man made. This clearly calls for close cooperation between the various scientific disciplines. For example, the treatment of exhaust fumes from motor vehicles has been of primary importance in measures taken to restrict the recent damage caused to woodland areas. The introduction of 3‐Way‐Catalyst technology has been regarded as a viable countermeasure. The following report is intended to describe a method for examining some side effects of catalyst usage. Accordingly, the chemical composition of microparticles emitted from combustion motors through the use of catalysts will be examined and some possible changes in the environment caused by such particles will be briefly considered. As in the area of research into catalysts for industrial synthesis a knowledge of the surface structure of such particles, i.e. the boundary layer between emission product and environment, is necessary in the investigation into their effects. Consequently, a surface sensitive technique from solid state physics, X‐ray photoelectron spectroscopy (XPS or ESCA) has found novel use in the area of environmental analysis. In the following report emphasis will be placed on the description of measurement techniques and the interpretation of the results obtained. After a critical consideration of the experimental methods, examples from two different series of measurements on diesel and Otto motors equipped with soot filters or 3‐way‐catalysts respectively, will be given. Hopefully, this report will also stimulate establishment of the use of EPS in environmental research techniques.