Pz-Radical Electron Structure in Polydiacetylene (PDA) Molecules
By ESR spectroscopy it is shown that the transient absorption and the delayed luminescence observed in PDA single crystals is due to a metastable triplet state of the individual conjugated chains. This triplet state is described by a configuration model in analogy to the ground-state carbene reaction intermediates of the solid-state polymerization reaction. ESR fine structure and hyperfine structure data are consistent with a transfer integral of t = − 1.1 eV and an energy difference of 2ɛ = 0.4 eV between buta-triene and acetylene structure per unit cell.
KeywordsTriplet State Configuration Model Transient Absorption Excited Triplet State Radical Electron
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