文章基本信息

标题：Assignment of the Q-Bands of the Chlorophylls: Coherence Loss via Q_x − Q_y Mixing
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作者：Jeffrey R. Reimers ; Zheng-Li Cai ; Rika Kobayashi 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2013
卷号：3
DOI：10.1038/srep02761
出版社：Springer Nature
摘要：We provide a new and definitive spectral assignment for the absorption, emission, high-resolution fluorescence excitation, linear dichroism, and/or magnetic circular dichroism spectra of 32 chlorophyllides in various environments. This encompases all data used to justify previous assignments and provides a simple interpretation of unexplained complex decoherence phenomena associated with Q_x → Q_y relaxation. Whilst most chlorophylls conform to the Gouterman model and display two independent transitions Q_x (S₂) and Q_y (S₁), strong vibronic coupling inseparably mixes these states in chlorophyll-a. This spreads x -polarized absorption intensity over the entire Q -band system to influence all exciton-transport, relaxation and coherence properties of chlorophyll-based photosystems. The fraction of the total absorption intensity attributed to Q_x ranges between 7% and 33%, depending on chlorophyllide and coordination, and is between 10% and 25% for chlorophyll-a. CAM-B3LYP density-functional-theory calculations of the band origins, relative intensities, vibrational Huang-Rhys factors, and vibronic coupling strengths fully support this new assignment.