Three-dimensional structure of J 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 fi rst time the structure of J aggregates of pseudoisocyanine chloride(PIC-Cl) dyes at a mica/solution interface in an aqueous PIC-Cl solution. The J agg regates were leaf-like islands in multilayers of PIC-Cl molecules. The mini mal size of the aggregate necessary for the J band was also revealed. Dye m olecules grow into the J aggregates at a mica/solution interface by a Volme r-Weber type growth process.