Total internal reflection ellipsometry

Detta är en avhandling från Linköping : Linköpings universitet

Sammanfattning: This thesis summarizes the work performed on the development and implementation of the optical measurement technique called total internal reflection ellipsometry (TIRE).The TIRE principle is based on spectroscopic ellipsometry performed under conditions of total internal reflection. This configuration is suitable for monitoring and analysis of thin semitransparent films and changes in/on these films due to exposure to various media (liquid or gas). When metal films are used this technique can be further extended with the surface plasmon resonance (SPR) effect forming a measurement method, which allows measurements with very high precision. The main advantages of TIRE are the possibility for measurements in opaque liquids and very good detection limits, both unavailable with the complementary techniques, ellipsometry and SPR, used in their conventional mode.The measurement principles of ellipsometry and surface plasmon resonance have been known for a long time and these techniques are currently widely used in various areas of science and technology. Furthermore, internal reflection ellipsometry has been reported several years ago and possibilities offered by this technique have been discussed by several scientists. However, so far there has been no attempt to give a more comprehensive report containing the combination of theoretical aspects, technical development and practical applications all-in-one. Therefore, the main goal of this work was to give some deeper insight into the TIRE technique by focusing on the following aspects: theoretical and mathematical tools used in TIRE and development of the measurement system with its applications. Unfolding the above - the aim of the TIRE project is to review what has been done so far in the area of TIRE and update this with the current results. Included is also developing a set of components of the TIRE measurement system, and understanding the possible technical problems which may show up, with an attempt to resolve them. Finally, the possible applications of the TIRE technique in various areas of science and technology are exemplified, with focus on the advantages over the currently used techniques.The TIRE technique is suitable for monitoring of adsorption/ desorption of molecules from various liquid/gas media on the surfaces of the material playing the role of the substrate, as well as for studying the material itself. Within the TIRE project three types of applications have been studied. The first was in situ studies of protein adsorption on thin metal films, with use of SPR extended TIRE. The information obtained was more precise and complete than usually obtainable from SPR and conventional ellipsometry. With appropriate technical setup there is a potential to resolve the morphology of adsorbed multi-layered protein structures with TIRE. The behaviour of proteins on metals is of great importance in many areas of bio-sciences, including medicine (e.g. implants in the human body). The other two applications studied were more technical, with possible industrial relevance: adsorption and subsequent cleaning of substances from milk (useful i.e. for pipeline monitoring in the diary industry) and studies on corrosion on thin copper layers (useful e.g. for circuit board control in the microelectronics industry).

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