Regensburg 2004 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 10: Light Induced Phenomena

CPP 10.3: Talk

Monday, March 8, 2004, 16:15–16:30, H 38

In-Situ Investigation of Surface Relief Grating Formation by X-Ray Scattering — •Oliver Henneberg, Thomas Geue, Marina Saphiannikova, and Ullrich Pietsch — Universiy of Potsdam, Physics, Structureanalysis, 14469 Potsdam

The formation of surface relief gratings in polymers is a quite phenomenon with poential for many possible applications but many open question concerning the underlying physical process. Surface relief gratings are made by an interference pattern of blue laser light onto a flat polymer film which contains azobenzene moieties. The cycling cis-trans conformation change leads to a movement of polymer chains far below the glass transition temperature.

We have probed the grating formation by combined in-situ visible light and x-ray scattering methods. The use of two different wavelengths allowed time depend information at two different length scales. With x-rays it is possible to probe very sensitive the beginning of the grating formation. Visible light scattering gives information for larger grating heights. We could calculate the scattering intensities of both probes by theoretical modelling of the polymer movement. It could be shown that a change of the polymer density is involved during the formation of the surface grating.