Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: POSTERS Polymer Physics

CPP 13.5: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Light induced lattice expansion in azopolymer films — •Sebastian Kramer, Padmanabh Veer, and Ullrich Pietsch — Department of Solid State Physics, University of Siegen, ENC, 57068, Siegen, Germany

Light induced lattice expansion of azopolymer films was observed under homogeneous illumination with polarized light of 514nm of about 1W. The polymer film made from pDR1M was irradiated parallel to the surface normal. The light induced deformation effects were probed using a low power He-Ne laser of wavelength (λ=633nm) at a fixed reflection angle of about 63 degree and recorded using a pair of photodiodes. Straight after switching the actinic light on the intensity of the probe laser shows a sudden jump followed by an oscillation behavior damped out as function of time. Evaluated in terms of Fresnel equations the sudden increase and the oscillations can be related to the change in the refractive index and an increase of film thickness under light illumination. Considering the Gaussian profile of the laser beam the evaluated increase in film thickness reaches a value of several 100nm in centre and decreases respectively towards the borders. The behavior can be explained in terms of light-induced visco-elastic flow.