Coherent Multidimensional Spectroscopy of the Oxygen Evolving Complex in Photosystem II

化学测量和成像以及化学系的化学结构、动力学和机制计划资助了威斯康星大学的约翰·C·赖特教授开发具有量子态分辨率的复杂分子系统的激光光谱分析方法。这些方法类似于大脑从三种类型的视网膜锥体细胞的反应中区分颜色的能力。激光方法使用三种不同的激光光束颜色来同时激发特定分子的三个量子态，进而推动光合作用。这些方法为发现植物如何通过分解光合作用中实际涉及的量子态来制造氧气提供了关键。主要的研究目标是应用新的激光方法来了解光合作用中的放氧机制。氧是在光系统II(PS II)的放氧中心(OEC)产生的。OEC含有锰、氧、钙离子和氨基酸配体。激光颜色将激发OEC的不同振动和电子态组合，使其有别于PS II中数量更多的分子。不同的过渡金属配位络合物钴胺将作为测试和开发方法的模型系统。该项目将解决随着OEC通过其不同的氧化状态而进行的量子态变化。这些变化将与NSF-STC计划的X射线激光生物学测量结果相关联。这项研究的影响通过以下方式扩大：代表不足的少数群体的参与；制定在大学课堂上实施主动学习所需的战略、材料和教育基础设施；以及通过不同的交流渠道传播研究。最广泛的影响是为我们未来的能源提供了一个如何有效收集和使用太阳能的模式。

The Chemical Measurement and Imaging and the Chemical Structure, Dynamics and Mechanisms Programs of the Chemistry Division have funded Professor John C. Wright of the University of Wisconsin to develop laser spectroscopy methods for measuring complex molecular systems with quantum state resolution. The methods are analogous to the brain's ability to distinguish colors from the response of the three types of retinal cone cells. The laser methods use three different laser beam colors to simultaneously excite three quantum states of specific molecules that proceed to drive photosynthesis. The methods provide the key for discovering how plants make oxygen by resolving the quantum states actually involved in photosynthesis. The primary research goal is applying the new laser methods to understanding the mechanism of oxygen evolution in photosynthesis. Oxygen is created at the oxygen evolution center (OEC) in photosystem II (PS II). The OEC contains Mn, O, and Ca ions and amino acid ligands. The laser beam colors will excite different combinations of vibrational and electronic states of the OEC that distinguish it from the much larger number of molecules in PS II. Different transition metal coordination complexes cobalamin will serve as model systems for testing and developing the methods. The project will resolve the quantum state changes as the OEC progresses through its different oxidation states. The changes will be correlated with those measured by the Biology with X-ray lasers NSF-STC program. The impact of this research is broadened by the participation of under-represented minorities; the development of strategies, materials, and the educational infrastructure required to implement active learning in college classrooms; and the dissemination of the research through different communication channels. The broadest impact is providing a model for how to efficiently collect and use solar energy for our energy future.