Investigation of chromophore-chromophore interaction by electro-optic measurements, linear dichroism, x-ray scattering, and density-functional calculations
- Optics and Plasma Research Department, Risoe National Laboratory, 4000 Roskilde (Denmark)
- Institute of Physics, University of Bonn, 53115 Bonn (Germany)
- Department of Physical and Theoretical Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, 91058 Erlangen (Germany)
- Danish Polymer Center, Risoe National Laboratory, 4000 Roskilde (Denmark)
- SIMAC - Svendborg International Maritime Academy, 5700 Svendborg (Denmark)
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 deg. 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.
- OSTI ID:
- 20706366
- Journal Information:
- Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, Vol. 72, Issue 3; Other Information: DOI: 10.1103/PhysRevE.72.036610; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-651X
- Country of Publication:
- United States
- Language:
- English
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