Three-dimensional Structure ofJ Aggregates of Pseudoisocyanine Chloride Dyes at a Mica/Solution Interface Revealed by AFM

By using tapping-mode atomic force microscopy (AFM), we revealed for the first time the structure of J aggregates of pseudoisocyanine chloridc(PIC-CI) dyes at a mica/solution interface in an aqueous PIC-CI solution. The J aggregates were leaf-like islands in multilayers of PIC-CI molecules. The minimal size of the aggregate necessary for the J band was also revealed. Dye molecules grow into the J aggregates at a mica/solution interface by a Volmer-Weber type growth process.