Title
Nature Of The Electronic Transitions In Thiacarbocyanines With A Long Polymethine Chain
Keywords
Anisotropy; Charge density; Cyanine dyes; Excited-state absorption; Saturable absorption; Solitonic charge wave; Symmetrical and asymmetrical forms; Symmetry breaking
Abstract
A detailed experimental investigation and quantum-chemical analysis of symmetric cyanines of different conjugation lengths have been performed with the goal of understanding the nature of the electronic transitions in molecules that possess a long chromophore. The nature of electronic transitions in cyanines with a relatively short chromophore (inside the cyanine limit) has already been investigated and many properties of these molecules are well understood. However, little is known about the nature of the transitions beyond the cyanine limit. Their unusual properties, which were proposed by Tolbert and Zhao to be connected with symmetry breaking, still remain unexplored. The analysis of the spectral data in various solvents and results of femtosecond pump-probe saturable absorption measurements enable us to conclude that an increase in the length of the chain leads to a symmetry breaking and the appearance of two forms with symmetrical and asymmetrical distributions of the charge density in the ground state. For thiacarbocyanines, symmetry breaking is predicted and observed for a pentacarbocyanine dye. Quantum-chemical calculations provide additional proof of this hypothesis. The excited-state absorption properties of a pentacarbocyanine in the visible region are also reported. For the first time we have observed an excited-state cross-section that is larger (≈3x) than the ground state cross-section at the peak spectral position. © 2004 Elsevier B.V. All rights reserved.
Publication Date
10-25-2004
Publication Title
Chemical Physics
Volume
305
Issue
1-3
Number of Pages
259-270
Document Type
Article
Personal Identifier
scopus
DOI Link
https://doi.org/10.1016/j.chemphys.2004.06.063
Copyright Status
Unknown
Socpus ID
4644295798 (Scopus)
Source API URL
https://api.elsevier.com/content/abstract/scopus_id/4644295798
STARS Citation
Lepkowicz, Richard S.; Przhonska, Olga V.; Hales, Joel M.; Fu, Jie; and Hagan, David J., "Nature Of The Electronic Transitions In Thiacarbocyanines With A Long Polymethine Chain" (2004). Scopus Export 2000s. 4681.
https://stars.library.ucf.edu/scopus2000/4681