The synthesis of 4-(N-hexadecylamino)azobenzene is described. This compound was characterized by elemental anal. and 1H NMR. Mixed monolayers with arachidic acid were prepared and deposited on hydrophobic optical glass or quartz slides. The UV-visible spectra of solns. and LB (Langmuir-Blodgett) films exhibit absorption max. at 396 and 388.5 nm, resp. The small blue shift indicates H-aggregate formation in the LB film. Absorbance increases as the no. of layers increases, but the peak position is unchanged, confirming the absence of mol. aggregates between adjacent layers and the good vertical uniformity of successive monolayers. The orientation of the azobenzene chromophores in the LB films was examined by using polarized light absorbance measurements. The diffraction patterns were determine and the Bragg peaks assigned (lattice spacing 5.49 nm). The LB films are built up into ordered multilayer films with periodic structure.

Key words: ULTRAVIOLET SPECTROPHOTOMETRY, X-RAY DIFFRACTION ANALYSIS, BENZENE AZO COMPOUNDS, L-B MEMBRANE