Photochemical isomerization in the absence of a potential barrier: origin of wavelength-dependent ground-state recovery kinetics
✍ Scribed by Ulf Åberg; Villy Sundström
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 590 KB
- Volume
- 185
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The photophysics and isomerization dynamics in the excited state of the molecule I,1 '-diethyl-4,4'-cyanine have been investigated. Earlier studies have indicated that the lsomerization reaction of this molecule is ofthe barrierless type. As such, it displays some interesting properties of the excited-state relaxation dynamics. In the present work, we investigate in detail the wavelength dependence of the observed ground-state recovery lifetimes, and show that this dependence is due to a dependence on the analyzing wavelength. We believe that the origin of the effect is the admixture of non-exponential fluorescence-decay components into the ground-state recovery signal. This results in apparently faster and non-exponential ground-state recovery kinetics in the part of the absorption spectrum, overlapping with the fluorescence spectrum.