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 : 28 JUN 1974

Pagination or Media Count : 44

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