Atomic Force and Scanning Near-Field Optical Microscopy Study of Carbocyanine Dye J-Aggregates
V. V. Prokhorova, M. G. Petrovab, N. N. Kovalevab and E. I. DemikhovbAffiliation:
Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky pr., Moscow, 119991 Russia.
AbstractAtomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) imaging of fibrillar J-aggregates of carbocyanine dye 3,3’-bis(2-sulfopropyl)- 5,5’,6,6’-tetrachloro-1,1’- dioctylbenzimidacarbocyanine (C8S3) have been conducted on mica and glass substrates at a room temperature. High resolution AFM imaging reveals that thick fibrils consist of narrow sub-fibrils with the cross diameter in the nanometer range. A model of the "elementary fibril" with the cross-dimension of 3х4 nm2 was proposed as the aggregate of two J-ladders oriented face-to-face by their hydrophobic sides while the dye molecules are oriented normaly to the long fibril axis. The SNOM measurements have been conducted in the contact mode indicating the large mechanical strength on the fibrillar J-aggregate morphology.
Carbocyanine dye, elementary fibril, J-aggregate, probe microscopy, high-resolution atomic force microscopy, scanning near-field optical microscopy
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