Photoisomerization of the Stilbenes: an Application of Chemical Spectroscopy

Author: Saltiel, Jack

Year: 1964

Degree: Dissertation (Ph.D.)

Advisor: Hammond, George Simms

Committee Member: Unknown, Unknown

Option: Chemistry

DOI: 10.7907/4BXD-4D28

Abstract

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Formation and quenching of stilbene triplet states by means of energy transfer is used in an attempt to elucidate the mechanism of [cis-trans] photoisomerization in this system.

It is found that the [cis-trans] ratios attained at the photostationary state in the presence of sensitizers map a "chemical spectrum" when plotted against the triplet state energies of the sensitizers. This spectrum is interpreted by assuming that stilbene triplet states can be produced by vertical or nonvertical energy transfer from the lowest triplet states of the sensitizers. A consistent picture is presented to account for the effect of sensitizer or quencher concentration on the stilbene photostationary states.

Evidence is presented which strongly supports the hypothesis that stilbene isomerization induced by direct absorption of light proceeds by way of the lowest triplet states.

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