| Research Abstract |
The J-aggregate of cyanine dyes, a sort of molecular clusters composed of 10-20 dye molecyles, is characterized by a sharp J-band and resonance fluorescence. In this study, we have fabricated integrated molecular assemblies incorporating two kinds of cyanine dyes in Langmuir-Blodgett (LB) films and polymer films. With an aid of spectro-scopic measurements, we have analyzed the structure and optical properties of novel dye assemblies. The cyanine dyes used in this work were 5,6,5', 6'-dibenzo-1,1'-diethyl-2,2'-cyanine chloride (dye I), 5,5'-dichloro-3,3'-diethyl-9-phenyl-thiacarbocyanine chloride (dye II), 3,3'-dimethyl-9-phenyl-4,5,4', 5'-naphthothiacarbocyanine chloride (dye III), 1,1'-diethyl-2,2'-cyanine chloride (dye IV), 1-methyl-1'-octadecyl-2,2'-cyanine perchlorate (S120), N,N'-dioctadecyl-oxacyanine perchlorate (S9), N,N'-dioctadecyl-thiacyanine perchlorate (S11). Integrated dye assemblies were classified into four types, separate (S) type, mosaic (M) type, persistence (HP) type and amalgamation (HA) type. We have carried out spectroscopic measurements and fluorescence microscopy observation by means of optical microscopes equipped with spectrophotometer and fluorometer, together with newly purchased Color-Chilled-CCD Camera and Color Monitor. It appeared that in LB films, dye I+dye II forms the S-aggregate, dye I+S120 and S9+S11 form the M- or HP-aggregate, while dye II+dye III gives rise to the HA-aggregate. In the polymer film, dye I+dye IV forms the S-aggregate. In the S-and M-aggregates, quenching and sensitization of resonance fluorescence due to excitation energy transfer were observed. Two conditions for realization of the HA-aggregate, steric requirement and electronic requirement, have been examined and a practical parameter THETA has been proposed.
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