SYNTHESIS AND NONLINEAR-OPTICAL PROPERTIES OF SOME ORGANIC SELF-ASSEMBLED FILMS ON HYDROXYLATED SUBSTRATE SURFACES

Films of some small molecules on hydroxylated silica surfaces have been prepared successfully by the self-assembly technique, using the condensation of the CHO group of 4-substituted benzaldehyde with the NH2 group of 4-substituted aniline derivatives. Second-harmonic generation (SHG) was observed in all the monolayers of the chromophores and changed with different pi-electron systems. The maximum chi((2)) was 7.9 X 10(-10) esu and the orientation angles of the chromophore dipoles of all the films were 33-38 degrees. This method is capable of generating multilayer films. For a Z-type multilayer, the SHG signal increases quadratically with the number of chromophore layers. The films have high structural stability.