Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)

O 14.55: Poster

Montag, 8. März 2004, 18:00–21:00, Bereich C

UV-photoinduced modification and surface anisotropy of polyimide studied by X-ray absorption spectroscopy and spectromicroscopy — •Michael Zharnikov1, Yukio Ouchi2, Masaki Hasegawa3, and Andreas Scholl41Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany — 2Department of Chemistry, Nagoya University, Nagoya, 464-8602 Japan — 3IBM Research, Tokyo Research Laboratory, Yamato, Kanagawa 242-8502, Japan — 4Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, CA 94720 USA

An alignment of liquid crystal (LC) molecules in a flat panel display is mediated by the anisotropic polyimide (PI) substrate. Whereas a conventional way to fabricate such a substrate is a mechanical rubbing of a PI, an alternative approach utilizes the irradiation of PI by linearly polarized UV-light. To get a basic understanding of the phenomenon of UV-light-induced anisotropy, we have performed NEXAFS spectromicroscopy measurements at the C, N, and O K-edges on a series of the polyimide films treated by linearly polarized UV-light through a mask. Fabricated patterns could be easily distinguished and imaged both for the parallel and perpendicular orientation of the electric field vectors of the UV- and synchrotron light. The UV-induced intensity changes of the characteristic absorption resonances at all probed absorption edges were monitored and related to the chemical modification of PI. From the analysis of the NEXAFS microspectra, the extent of the UV-induced anisotropy could be estimated in good agreement with our previous spectroscopic results.

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