报告题目：Understanding the role of the primary charge donor during solar-energy conversion in purple bacteria, excition transport in photosystem I, and the spectroscopy of the schlorophylls.
主讲人：Prof. Jeffrey R. Reimers
时间：2013年10月31日下午2:00-4:00
地点：生命科学与技术学院二楼会议室
Jeffrey R. Reimers教授是澳大利亚悉尼大学化学院的教授、澳大利亚科学院院士。
Jeffrey R. Reimers教授的研究领域包括电子器件、光合作用、光伏电池、分子电子学、化学光谱、溶剂化效应、电吸收光谱、和电子结构的计算方法等等。
Jeffrey R. Reimers教授于1979年和1983年获得澳大利亚国立大学学士和博士学位，1983-1985年在美国加利福利亚大学博士后。Jeffrey R. Reimers教授于2007年被聘为悉尼大学教授。Jeffrey R. Reimers教授于2010年当选澳大利亚科学院院士，现同时也是澳大利亚皇家化学会会员，在国际期刊发表论文150余篇。
摘要：
Natural photosynthesis is the paradigm used for the design and understanding of many artificial light-harvesting and solar-energy conversion technologies including artificial photovoltaics and artificial photosynthesis, and influences related fields such as organic light-emitting diodes (OLEDs) also. The natural system involves very many aspects and in this seminar three are addressed: the absorption of light by chlorophylls, their transmission of this energy through exciton transport, and the conversion of solar to electrical energy through primary charge separation. Understanding the chemical properties of these systems requires detailed interpretations to be made of spectroscopic and electrochemical data as a function of the molecular environment, which can be changed by site-directed mutagenesis, dissolution of components in solvents, or by the application of large external electric fields (Stark spectroscopy). Because of the size of these systems, accurate computational modelling is very difficult. This seminar presents the development of three new techniques designed to overcome these challenges for three specific problems, showing how they can be used to determine the critical aspects of the associated operation mechanisms. The techniques are of widespread relevance in both biological and materials applications, however. Problem1: the role of the special pair radical cation in primary charge separation. The most informative spectroscopic measurement for this system is the intervalence hole-transfer band which was first measured in 1992 but assigning this spectrum in detail took continuous study until 2004. This resulted in a comprehensive model, expressed at both simple qualitative and complex quantitative levels for the electrochemical and spectroscopic properties of the system. Subsequent detailed Stark spectroscopy verified the critical aspects of the model which describes how protein mutation controls the efficiency of solar-energy capture. Problem 2 is exciton transfer and the spectroscopy of photosystem I. The crystal structure of the protein provides detailed information needed to understand how energy flows in this system, but the experimental resolution is insufficient to provide quantitative accuracy. We describe new methods that allow detailed quantum electronic-structure calculations to be incorporated either along-side of standard protein X-ray structure refinement or else incorporated into the procedure, eliminating the reliance of these methods on empirical data. It is hoped that the methods being developed will have widespread influence on protein crystallography. Problem 3is the spectroscopy of chlorophyll itself. Its spectroscopic properties determine all exciton transfer and quantum coherence in biological photosystems but for the assignment of its critical Q-band region, two possibilities have been debated over the last 30 years. Our work shows how computational modelling questions both of these alternatives, leading to the design of new experiments performed by the leading research groups advocating the alternate assignments. The results of these experiments, combined with the development of new quantum spectroscopic interpretation methods, led to a new assignment that reproduced all known spectroscopic properties of the Q band of chlorophyll ides.
