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Saphiannikova, M. ; Henneberg, O; Gene, TM; Pietsch, U; Rochon, P;
Nonlinear effects during inscription of azobenzene surface relief gratings

Surface relief gratings were inscribed on azobenzene polymer films using a pulselike exposure of an Ar+ laser. The inscription process was initiated by a sequence of short pulses followed by much longer relaxation pauses. The development of the surface relief grating was probed by a He-Ne laser measuring the scattering intensity of the first-order grating peak. The growth time of the surface relief grating was found to be larger than the length of the pulses used. This unusual behavior can be considered as a nonlinear material response associated with the trans-cis isomerization of azobenzene moieties. In this study the polymer stress was assumed to be proportional to the number of cis-isomers. One-dimensional viscoelastic analysis was used to derive the polymer deformation. The rate of trans-cis isomerization increases with the intensity of the inscribing light; in the dark it is equal to the rate of thermal cis-trans isomerization. The respective relaxation times were estimated by fitting theoretical deformation curves to experimental data.

Journal of Physical Chemistry / B 108

15084 -15089


Erschienen am
August 2004

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Mechanik und Struktur