PROPERTIES OF POLYMERIC LANGMUIR-BLODGETT-FILMS CONTAINING SULFONYL-SUBSTITUTED AZOBENZENE MOIETIES FOR 2ND-HARMONIC GENERATION

Polymeric Langmuir-Blodgett films incorporating a sulphonyl-substitute d azobenzene chromophore have been studied by second harmonic generati on. These films are more stable to light and more transparent than alt ernatives based on hemicyanine and other azo dyes that have been used previously. The initial 100 nm of polymeric LB film, nearest the subst rate, exhibits a nonlinear susceptibility of chi(pp)((2)) = 6.3 pm V-1 and a chromophore nonlinear vector susceptibility of magnitude beta = 46 x 10(-50) C-2 m(-3) V-2. A loss of performance is observed for mol ecular layers a distance greater than 100 nm from the substrate, which is reflected in a reduced but uniform nonlinearity in the layers depo sited later in the sample fabrication process. (C) 1998 Elsevier Scien ce S.A. All rights reserved.