Excitation Energy Transfer by Coherent and Incoherent Mechanisms in the Peridinin–Chlorophyll a Protein
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- 作者：Soumen Ghosh ; Michael M. Bishop ; Jerome D. Roscioli ; Amy M. LaFountain ; Harry A. Frank ; Warren F. Beck
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2017
- 出版时间：January 19, 2017
- 年：2017
- 卷：8
- 期：2
- 页码：463-469
- 全文大小：408K
- ISSN：1948-7185
文摘
Excitation energy transfer from peridinin to chlorophyll (Chl) a is unusually efficient in the peridinin–chlorophyll a protein (PCP) from dinoflagellates. This enhanced performance is derived from the long intrinsic lifetime of 4.4 ps for the S2 (11Bu+) state of peridinin in PCP, which arises from the electron-withdrawing properties of its carbonyl substituent. Results from heterodyne transient grating spectroscopy indicate that S2 serves as the donor for two channels of energy transfer: a 30 fs process involving quantum coherence and delocalized peridinin–Chl states and an incoherent, 2.5 ps process initiated by dynamic exciton localization, which accompanies the formation of a conformationally distorted intermediate in 45 fs. The lifetime of the S2 state is lengthened in PCP by its intramolecular charge-transfer character, which increases the system–bath coupling and slows the torsional motions that promote nonradiative decay to the S1 (21Ag–) state.