Delocalization of Coherent Triplet Excitons in Linear Rigid Rod Conjugated Oligomers

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• 作者：Christian HintzePatrick Korf ; Frank Degen ; Friederike Schütze ; Stefan Mecking ; Ulrich E. SteinerMalte Drescher
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2017
• 出版时间：February 2, 2017
• 年：2017
• 卷：8
• 期：3
• 页码：690-695
• 全文大小：432K
• ISSN：1948-7185

文摘

In this work, the triplet state delocalization in a series of monodisperse oligo(p-phenyleneethynylene)s (OPEs) is studied by pulsed electron paramagnetic resonance (EPR) and pulsed electron nuclear double resonance (ENDOR) determining zero-field splitting, optical spin polarization, and proton hyperfine couplings. Neither the zero-field splitting parameters nor the optical spin polarization change significantly with OPE chain length, in contrast to the hyperfine coupling constants, which showed a systematic decrease with chain length n according to a 2/(1 + n) decay law. The results provide striking evidence for the Frenkel-type nature of the triplet excitons exhibiting full coherent delocalization in the OPEs under investigation with up to five OPE repeat units and with a spin density distribution described by a nodeless particle in the box wave function. The same model is successfully applied to recently published data on π-conjugated porphyrin oligomers.