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  • 理学院数理讲坛(2018年第15讲)
  • 发布时间:2018年04月23日 16:13 作者: 点击:[]
  • 理学院数理讲坛2018年第15讲)

    报告题目:Two-dimensional spectroscopic studies of energy and charge transport in the photoactive systems

    报告人:段红光 德国汉堡大学 博士,德国马普研究所 博士后

    报告时间:2018年5月4日(星期五)10:00-11:00

    报告地点:理学院 116

     

    报告摘要:During the first step of photosynthesis, the energy of solar photons is captured by antanna pigment protein complexes and subsequently, it is transferred to the reaction center for the charge separation and water splitting. Todays understanding of the energy transfer includes the fact that the excitons are delocalized over a few neighboring sites, but the role of quantum coherence is considered as irrelevant for the transfer dynamics because it typically decays within a few tens of femtoseconds. The orthodox picture of incoherent energy transfer has been challengened by ultrafast optical spectroscopy of Fenna-Matthews-Olson complex, in which interference exceptionally long-lived electronic coherence. Here, the process of energy transfer has been reexamined and we show that the optical 2D photon echo spectra of this complex at ambient temperature in aqueous solution do not provide evidence of any long-lived electronic quantum coherence, but confirm the orthodox view of rapidly decaying electronic quantum coherence on a timescale of 60 fs. Moreover, on the basis of our theoretical calculations, we show the lifetime of electronic coherence is too short to be enhanced by vibrational coherence, which also exclude the observation of vibronic coherence. Our results can be considered as generic and give no hint that electronic quantum coherence plays any biofunctional role in real photoactive biomolecular complexes. Because in this structurally well-defined protein the distances between bacteriochlorophylls are comparable to those of other light-harvesting complexes, we anticipate that this finding is general and directly applies to even larger photoactive biomolecular complexes. Moreover, based on 2D spectroscopy, we also studied charge-separation signature in PSII reaction center, exciton dissociation dynamics in perovskites and the binding energy in dopant materials.

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