Excitonic Relaxation and Coherent Vibrational Dynamics in Zinc Chlorin Aggregates for Artificial Photosynthetic Systems

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• 作者：Dongjia Han ; Juan Du ; Takayoshi Kobayashi ; Tomohiro Miyatake ; Hitoshi Tamiaki ; Yanyan Li ; Yuxin Leng
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：September 17, 2015
• 年：2015
• 卷：119
• 期：37
• 页码：12265-12273
• 全文大小：569K
• ISSN：1520-5207

文摘

The excitonic relaxation and coherent vibrational dynamics in stairlike zinc chlorin aggregates prepared for mimicking chlorosome in nature have been studied simultaneously by 6.8 fs real-time vibrational laser spectroscopy. The relaxation from Q-exciton state to the dark nonfluorescent charge-transfer (CT) state is determined to be 850 卤 70 fs. The spectral distribution of the molecular vibrational amplitude has been discussed in terms of the difference in the equilibrium positions of potential curves between the ground state and the excited state. Since the displacement in the coordinate space from the potential minimum of the ground state to that of the excited states is small, coherent oscillations generated by the impulsive excitation are strongest where the slope of the excitonic resonance is largest. Consequently, the probe wavelength dependence of the amplitude modulation follows the first derivative of the excitonic resonance, and 蟺 phase jump has been observed. Excitonic transition energy modulation caused by the coherent molecular vibrations has also been studied, and the vibrational mode with a low frequency of 146 cm^鈥? is found to play a dominating role in the transition energy shift effect.