The excited-state geometry of conjugated dienes and characterization of a quantum chain-transfer mechanism of energy transfer

Citation

Hyndman, Harry Lester (1968) The excited-state geometry of conjugated dienes and characterization of a quantum chain-transfer mechanism of energy transfer. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-02092009-090005

Abstract

An investigation has been carried out to determine whether the geometry corresponding to the lowest lying triplet state of conjugated dienes is in the form of a 1, 4-biradical system or an allyl-methylene system (a "1, 2-biradical"). This has been done by measuring the various quantum yields for cis-trans isomerization of these dienes and comparing the results with certain previously conceived empirical standards and to the criteria imposed by the proposed mechanism.

During the course of this investigation, a novel and very interesting phenomenon was uncovered. It appears that a quantum-chain mechanism, heretofore unreported for this type of system, is in operation in at least the early stages of the photoisomerization process. Characterization of such a mechanism and the chain propagating species has been carried out.

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