The photoinduced anisotropy of second harmonic generation in monolayered Langmuir—Blodgett films

Photoinduced Molecular Reorientation in Optical Nonlinear Langmuir−Blodgett Films

“…Our result is different from the recent work by Aktsipetrov et al, which concluded that molecules in LB monolayers would reorient their chromophore axes toward a direction perpendicular to the field polarization because of an increase of interaction of photoexcited molecules under illumination of a visible polarized CW radiation (1.5 × 10 3 W m -2 , much weaker than ours). We attributed our observed molecular reorientation to the dipole interaction between hemicyanine molecules and the strong external field (6 × 10 5 V m -1 or peak power density of 5 × 10 8 W m -2 ).…”

Azo Chromophore-Functionalized Polyelectrolytes. 1. Synthesis, Characterization, and Photoprocessing

“…For reversible optical storage and related applications, polarized light has been used to induce reorientation of the azobenzene groups through repeated trans−cis photoisomerization and subsequent cis−trans relaxation of azobenzene groups. − Reversible holographic phase gratings have been formed by optically induced birefringence. − Recently, direct formation of surface relief grating on azobenzene polymer films has been reported. − The surface relief gratings were formed upon exposure to an interference pattern of Ar + laser beam at modest intensities without any subsequent processing steps. The large-scale macromolecular motion is attributed to the photoinduced trans−cis−trans isomerization cycles of azobenzene chromophores and the forces experienced by the chromophore dipoles in the electric field gradient of the standing wave pattern. , At the present stage, the photoprocessability of different types of polymer matrixes containing azobenzene moieties and the photoresponse behavior of different systems are being pursued to fully understand the structure−property correlation and to develop more versatile new materials.…”

“…[14][15][16][17][18][19][20] For reversible optical storage and related applications, polarized light has been used to induce reorientation of the azobenzene groups through repeated trans-cis photoisomerization and subsequent cis-trans relaxation ( of azobenzene groups. [21][22][23] Reversible holographic phase gratings have been formed by optically induced birefringence. [24][25][26] Recently, direct formation of surface relief grating on azobenzene polymer films has been reported.…”

Effect of the deposition type on the structure of terthiophene-vinylbenzoate Langmuir–Blodgett films

“…The reasons for rearrangement may be traced back to more favorable energetic arrangements. Based on secondorder nonlinear optical measurements, which are highly sensitive to noncentrosymmetry and therefore to orientational order, Z-type arrangement has been reported only for a few compounds [8][9][10][11]. In most cases, the orientation was lost after 5-10 layers.…”