Table of Contents
Laser Chemistry
Volume 8, Issue 1, Pages 39-47
http://dx.doi.org/10.1155/LC.8.39

Picosecond Absorption Spectroscopy of Polymethine Cis-Trans Isomerization

1Chemical Department, Center of Optical Spectroscopy, Friedrich-Schiller-University Jena, Jena DDR-6900, Germany
2Laser Research Center, V. Kapsukas University, Vilnius 232054, Lithuania

Received 24 July 1987; Accepted 3 September 1987

Copyright © 1988 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Results are presented of time resolved fluorescence and absorption investigations of DDEOCI (3,3'-diethyl-6,6'-diphenyl-9-ethyl-oxacarbocyanine iodide) in solvents which differ in polarity and viscosity. The measured picosecond absorption and fluorescence kinetics probed at various wavelengths of the polymethine dye studied can be fitted to a double exponential decay with a minor fast component of lifetime τ1 and a major slower component of lifetime τ2. Furthermore, probing in the S1S0 absorption region and in the fluorescence region results in a residual with a lifetime of some ns and belonging to the detected red-shifted photoisomer with a low quantum yield (φ < 10%). The lifetime and the preexponential factors of the two components are in methanolic solution uneffected by changes of the anion.

The detected two picosecond lifetime components are supposed to belong to two isomeric species (all-trans and mono-cis isomer) with strongly overlapping absorption spectra.