Large absorption reduction for mesoscopic thiacyanine J aggregates in solution

An apparent large absorption reduction was observed for a thiacyanine J agg regate in solution. Since fluorescence microscopy proved that the J aggrega te formed a mesoscopic rod-like structure (several tens of micrometers in l ength and about 1 mum in width) in solution, the reduction was due to that of the apparent absorption cross-section caused by formation of the aggrega te particles, indicating that no light transmitted through the region of pa rticles composed of strongly absorbing chromophore units with the spectrosc opic characteristics of J aggregates. The absorption behaviors were also si mulated quantitatively by the present model. (C) 2001 Elsevier Science B.V. All rights reserved.