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Raman Study of the Photoisomerization and Angular Reorientation of Azobenzene Molecules in a DR1‐Doped Polymer Matrix
Author(s) -
Lagugné Labarthet F.,
Sourisseau C.
Publication year - 1996
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199606)27:6<491::aid-jrs988>3.0.co;2-g
Subject(s) - photoisomerization , raman spectroscopy , azobenzene , materials science , raman scattering , dichroism , resonance (particle physics) , polymer , doping , absorbance , photochemistry , isomerization , molecular physics , analytical chemistry (journal) , optics , chemistry , optoelectronics , organic chemistry , atomic physics , physics , composite material , catalysis
The trans cis photoisomerization and angular reorientation of an azobenzene derivative (DR1) in dye‐doped polymer matrices [poly(methyl methacrylate)], induced by linearly polarized visible illumination (λ 0 =496.5 nm), were investigated by dichroism measurements in the visible region and by polarized resonance Raman experiments. Upon irradiation, the absorbance variations of low optical density thin‐film samples, with dye concentrations ranging from 1.3 to 5 wt%, were well reproduced by a simple three‐level model, taking into account the cis population and the angular redistributions and relaxations. Equations for Raman scattering in the initial isotropic samples (‘erased’) and in the illuminated anisotropic samples (‘written’) were derived. They were compared with the polarized resonance Raman intensities obtained for a 3% DR 1‐doped polymer film under two weak pumping regimes (10 and 15 mW cm −2 ). This allowed the estimation of the 〈 P 2 〉 and 〈 P 4 〉 order parameters for various vibrational modes (ν S NO 2 , νN = N, ν 19a , ν 8a ) and a better insight into the primary intramolecular orientational mechanisms. It was thus demonstrated that valuable information on the dynamics in such potential optoelectronic systems can be obtained from resonance Raman experiments.