Journal article
Investigation of chromophore-chromophore interaction by electro-optic measurements, linear dichroism, x-ray scattering, and density-functional calculations
Risø National Laboratory for Sustainable Energy, Technical University of Denmark1
University of Bonn2
Friedrich-Alexander University Erlangen-Nürnberg3
Department of Energy Conversion and Storage, Technical University of Denmark4
Imaging and Structural Analysis, Department of Energy Conversion and Storage, Technical University of Denmark5
Department of Physics, Technical University of Denmark6
Svendborg International Maritime Academy7
Free-beam interferometry and angle-resolved absorption spectra are used to investigate the linear electro-optic coefficients and the linear dichroism in photoaddressable bis-azo copolymer thin films. From the first- and second order parameters deduced, the chromophore orientation distribution is calculated and displayed for several poling temperatures and chromophore concentrations.
The influence of dipole-dipole interaction on the overall polymer dynamics is discussed. The first order parameter, and therefore the Pockels effect, peaks for a poling temperature of around 10 degrees C above the glass transition. The decrease of the Pockels effect above this temperature region is triggered by a head-to-tail chromophore orientation, i.e., a transition to a microcrystalline phase, increasing the second order parameter.
Comparison of the experimentally observed absorption spectra and those obtained by density-functional calculations support the picture of differently aligned bis-azo dye molecules in a trans,trans configuration. Complementary wide-angle x-ray scattering is recorded to confirm the various kinds of ordering in samples poled at different temperatures.
Language: | English |
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Year: | 2005 |
Pages: | 036610 |
ISSN: | 24700053 , 24700045 , 15502376 and 15393755 |
Types: | Journal article |
DOI: | 10.1103/PhysRevE.72.036610 |
ORCIDs: | Andreasen, Jens Wenzel and Nielsen, Martin Meedom |