Abstract

Cyanine dyes and their aggregates are very important for applications in laser mode-locking, photography and photobiology. At low temperatures and high concentrations, it is surprising that a new, sharp and intense absorption band appears at the reddest side (575 ± 3 nm) of the dye monomer 523 nm broad absorption spectra, or so-called J-band, first discovered by E. E. Jelley.1 It is considered a sensitive indication of the formation of a strongly coupled filament aggregate state of dye molecules in solution. This aggregate state bridges the gap between disorder molecules and a crystalline lattice.

© 1991 Optical Society of America