Chromophoric self-assembled NLO multilayer materials. Real time observation of monolayer growth and microstructural evolution by in situ second harmonic generation techniques

Shlomo Yitzchaik, Stephen B. Roscoe, Ashok K. Kakkar, David S. Allan, Tobin J Marks, Zuyan Xu, Tongguang Zhang, Weiping Lin, George K. Wong

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The self-assembling adsorption/quaternization of a (dialkylamino)stilbazole nonlinear optical chromophore precursor onto benzyl chloride-prefunctionalized surfaces is studied in situ by polarized second harmonic generation techniques. The measurements reveal that the self-assembly kinetics are approximately biexponential (I1/2 ∼ (1 - α1e-k1t - α2-k2t)) with a rapid initial phase, followed by a slower second phase. The in situ measurements also indicate that the average tilt angle of the chromophore dipole moment direction with respect to the surface normal increases significantly (∼20° → 42°) in the initial phases of chromophore adsorption and then remains nearly constant. These results suggest substantial chromophore-chromophore electrostatic and steric repulsion as monolayer growth proceeds. The maximum chromophore coverage observed corresponds to ∼49 Å2/ molecule and χ(2) = 3 × 10-7 esu at λ = 1064 nm.

Original languageEnglish
Pages (from-to)6958-6960
Number of pages3
JournalJournal of Physical Chemistry
Issue number27
Publication statusPublished - 1993


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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