Düsseldorf 2007 – wissenschaftliches Programm

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SYOH: Symposium Optische Hochleistungsbeschichtungen für den Einsatz in Lasersystemen und anderen Anwendungen

SYOH 7: Poster Optische Hochleistungsbeschichtungen

SYOH 7.4: Poster

Mittwoch, 21. März 2007, 17:30–18:30, Poster A

Photocatalytical measurements with thin films of evaporated stearic acid — •Thomas Neubert, Wenzao Sun, Frank Neumann, and Michael Vergöhl — Fraunhofer Institute for Surface Engineering and Thin Films, Bienroder Weg 54E, 38108 Braunschweig, Germany

We show a simple and quantitative method for the measurement of the photocatalytic activity of transparent layers. Such photocatalytic layers could be used for selfcleaning optical devices such as mirrors or lenses. The developed measuring method uses thin films of evaporated stearic acid as a well defined organic pollution. These films show a good homogeneity of the thickness and a high scattering of the visible light. A good correlation between the area-related mass and the optical haze of the stearic acid films was found. So the decomposition of the stearic acid by UV-light can be observed by optical haze measurements. From the change of the haze value with time a decomposition rate and from this in turn a photocatalytic activity can be calculated. Advantages of this method are the good reproducibility and simplicity, the possibility to use multiple photocatalytic substrates, a measuring time of less than an hour for samples with a good activity and the use of a non toxic and inexpensive organic material such as stearic acid.