Date of Award
Doctor of Philosophy
Chemical and Biological Engineering
G. L. Schrader
Infrared reflection-absorption spectroscopy has been used extensively in the study of adsorbates and thin films on metal surfaces, but little work has been performed on semiconductor and metal oxide surfaces due to the lack of sensitivity of the technique on these surfaces;In this work, IRRAS has been used to investigate the optical properties of thin film structures consisting of an optically thin layer of the nonmetallic component on an optically thick reflecting metal film. The sensitivity of the technique has been investigated by the use of thin polymer films of various thickness spun on thin film structures and compared with the transmission infrared spectra of similar films. The technique showed remarkable sensitivity to the thin films, several orders of magnitude more sensitivity than the corresponding transmission spectra. The technique was applied to the deposition of thin palladium films on silicon and copper surfaces by the decomposition of palladium acetate. Thin films of the acetate reacted much differently under oxidizing and reducing atmospheres and on different substrates, suggesting that substrate interactions play an important role in the decomposition process;Investigations were performed in order to determine the applicability of the technique to the study of thin layers and adsorbed molecules on metal oxide catalyst materials. It was determined that the technique exhibits sufficient sensitivity for the study of reaction and adsorption processes on metal oxide surfaces while avoiding the limitations of low surface area and low infrared transmittance. In addition, structural and compositional changes in the thin films were easily observed. The reactions of thin molybdenum trioxide films were studied in order to investigate the sensitivity of the technique to thin catalyst films. Both structural and compositional changes in thin oxide films were easily observable as a function of the atmosphere and reacting molecules above the film.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Steven James Finke
Finke, Steven James, "Infrared reflection-absorption spectroscopy of thin film structures " (1988). Retrospective Theses and Dissertations. 8843.