STRUCTURE AND ORIENTATION OF 1-HYDROXYL-5-HEXADECYCLOXY-NAPHTHALENE LB FILMS STUDIED BY UV-VIS AND FTIR SPECTROSCOPY

Ultraviolet-visible (W-Vis), infrared transmission, and reflection abs orption(RA) spectra have been measured for one-and multi-monolayer Lan gmuir-Blodgett(LB) films of C(16)H(33)ONaph(1,5)OH at various temperat ure to investigate dependencies of the aggregation and phase transitio ns on the number of monolayers. The UV-vis spectra of the LB films hav e revealed that the C(16)H(33)ONaph(1,5)OH forms aggregates in the LB film. From the temperature dependence of UV-vis absorption spectra, it is clear that the aggregate is gradual converted to monomer upto 80 d egrees C. A comparison of the infrared transmission and RA spectra rev eals that the hydrocarbon chains are tilted considerably in the LB fil m. As for the naphthalene ring part, the result suggest that the ring plane is oriented approximately perpendicular to the substrate surface The Temperature dependence of infrared transmission spectra have been measured for 1-, 3-, and 11-monolayer LB films to investigate depende nce of phase transitions on the number of monolayers. These observatio ns show that the one-monolayer LB films does not have a clear order-di sorder transition, while the three-and eleven-monolayer films have a p hase transition near 60 degrees C. Therefore, it seems that the title angles of both the alkyl chain and chromophore part change largely con comitantly with the conversion from the aggregate to the monolayer.