J-aggregate formation of dyes in Langmuir–Blodgett films

J-aggregate formation of dyes in the Langmuir–Blodgett (LB) films was examined. UV illumination of a single-layer LB film of an amphiphilic spiropyran caused the photoisomerization of spiropyran into merocyanine, followed by the formation of J-aggregates of merocyanine. A large morphological change accompanied the J-aggregation. Alternate illumination of mixed LB films of dyes and azobenzene triggered the formation of J-aggregates of dyes in the films irrespective of whether the dyes were photochromic or not. The J-aggregation of this type was also accompanied by large morphological changes.