Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 4: Organische Dünnschichten I

O 4.8: Vortrag

Montag, 8. März 2004, 13:00–13:15, H43

Calculation of the optical constants of thin films from just one spectral measurement and its application to organic films — •Robert Nitsche, Holger Pröhl, Thomas Dienel, and Torsten Fritz — Institut für Angewandte Photophysik, TU Dresden

The interpretation of optical thin film spectra is usually not straight forward since the shape of the spectra is strongly influenced by the substrate. Therefore, one has to extract the optical constants of the film, namely the index of refraction n and the absorption coefficient k. Here, we present a new method which allows to determine the optical constants from just one spectral measurement. The algorithm makes explicit use of the fact that n and k are connected by a Kramers-Kronig transformation. The successful application of the method is demonstrated on both, analytically generated and experimentally recorded examples. For this contribution we chose a Differential Reflectance Spectrum (DRS) of a thin film of the organic semiconductor PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) on HOPG (Highly Oriented Pyrolytic Graphite). This example has been selected since its optical spectrum does not resemble the material’s absorption at all.