Regensburg 2007 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 8: POSTER: Polymer Physics
CPP 8.26: Poster
Montag, 26. März 2007, 16:00–18:00, Poster B
Temperature resolved investigation of grating formation on azobenzene polymer films. — •padmanabh veer1, ullrich pietsch1, and paul rochon2 — 1Dept. of Solid State Physics,University of Siegen,ENC,Siegen,57068,Germany. — 2Dept. of Physics,Royal Military College,Kingston,Ontario,Canada,k7l3ng.
It was discovered 10 years ago that the exposure of an initially flat surface layer of an azobenzene-containing polymer to a holographic light pattern leads to the formation of surface relief structures (SRG) accompanied by a mass transfer over several micrometer. Many authors have investigated the process of SRG formation [1,2]. However, the nature of the driving force of this process is still unclear. We performed temperature resolved inspections of the SRG formation. The experiment was performed in a vacuum chamber to avoid the hot air turbulence. The sample is illuminated with circularly polarised light of wavelength 514nm and probed with He-Ne laser of wavelength 633nm.Inspecting the first order diffraction peak of a He-Ne laser, it has been seen that the grating inscription rate as well as the grating efficiency decrease with increasing sample temperature. No SRG formation is possible approaching the glass transition temperature 'Tg' of the polymer film. A simple model considering two competitive processes can explain the data, the light induced alignment of chromophores along the valleys of the SRG and the thermally induced disorder of chromophores. [1] Rochon, P. et. al. Appl. Phys. Lett. 1998,72,2096. [2] Barrett, C. et. al. J. Phys. Chem. 1996,100,8836