Accession Number:

AD0781284

Title:

Photophysical Effects of Stereoisomers in Thiacarbocyanine Dyes.

Descriptive Note:

Technical rept.,

Corporate Author:

UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY

Personal Author(s):

• Knudtson,J. Thomas
• Eyring,Edward M.

Report Date:

1974-06-28

Pagination or Media Count:

44.0

Abstract:

Fluorescence, excitation and transient absorption were used to characterize two stereoisomers in 3,3-dimethylthiacarbocyanine and 3,3-dimethyl-9-ethylthiacarbocyanine. The trans isomer fluoresces at room temperature with increasing intensity at lower temperatures. The cis isomer fluoresces in alcoholic glasses at - 196C. Substitution of an ethyl group for a proton in the 9 position greatly increases the cis concentration but has little affect on the absorption spectra of the stereoisomers. The rate of ground electronic state cis-trans isomerization was measured as a function of temperature, and a new fluorescence peak was observed at high laser powers that is attributed to excimer formation. Author

Descriptors:

• *Stereochemistry
• Visible spectra
• Emission spectra
• Cyanine
• Molecular isomerism
• Dyes
• Fluorescence
• Excitation
• Absorption spectra
• Nitrogen heterocyclic compounds
• Sulfur heterocyclic compounds
• Pulses

Subject Categories:

• Organic Chemistry
• Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE