SELF-ASSEMBLED CHROMOPHORIC THIN-FILM NLO MATERIALS - EFFECT OF COUPLING AGENT SURFACE FUNCTIONALIZATION AND ION-EXCHANGE PROCESSES ON 2ND-HARMONIC GENERATION CHARACTERISTICS

A systematic study of the reaction of 1-chloromethyl-4-(2-trichlorosil ylethyl)-benzene (coupling agent) with the surface Si-OH groups of gla ss for times from 15 min to 48 h, followed by stilbazole chromophore p recursor deposition/quaternization, is reported. Second harmonic gener ation characteristics of these thin film materials indicate that a 15 min coupling agent reaction attains approximately 65% of full surface coverage (based on chi(zzz)(2)) of benzylic chloride moieties, but tha t 24 h is the optimal time for maximum coverage. The surface-anchored chromophoric chloride salts in such materials undergo facile ion excha nge with iodide, p-aminobenzenesulphonate, and ethyl orange, leading t o enhancements in chi(zzz)(2) of up to 50%.