STUDY OF THE ELECTRONIC STATE OF THE MANGANESE CLUSTER IN PHOTOSYSTEM II : AN APPROACH BY SOFT X-RAY EMISSION SPECTROSCOPY

本研究的目的是在光系统II中对析氧络合物锰簇进行Mn 2p软x射线吸收/发射测量。为了将仅限于固体系统或气体系统的软x射线吸收/发射测量应用于溶液系统，我们改进了以下三点：软x射线发射光谱仪的开发——平衡高能量分辨率和高检测效率——可以在30分钟内测量吸附在衬底上的单层的软x射线发射，能量分辨率为1000(E/ΔE).2。超高真空条件下si3n_4膜溶液池的研制我们利用一种与超高真空相容的密封胶，成功地将约2μl的溶液样品保持在两片厚度为200nm的si3n_4薄膜之间。我们用该细胞测量了一种稳定致密（-10mM）肌红蛋白的铁2p软x射线吸收和发射测量。研制一种降低辐射损伤的样品扫描系统我们研制了一种利用溶液池的样品扫描系统。然而，控制样品位置所需的软x射线开放区域和限制真空防护的开放区域不太适合，因此我们在测量时放弃了对样品位置的扫描。相反，我们开发了一种体敏感光谱仪，一种高能光电发射光谱仪，将溶液样品置于低真空中。

The purpose of this study was to perform Mn 2p soft x-ray absorption/emission measurement of the oxygen evolving complex, manganese cluster, in photosystem II. In order to apply soft x-ray absorption/emission measurement which is limited to a solid system or gas system, to a system in solution, we have improved the following three points:1.Development of the soft X-ray emission spectrometer --balancing high energy resolution and high detection efficiency--It has become possible to measure the soft x-ray emission from a monolayer adsorbed on a substrate in only 30 minites, with the energy resolution of 1000(E/ΔE).2.Development of a solution cell with Si_3N_4 membrane to hold a solution in an ultra high vacuumWe have succeeded to maintain about 2μl solution sample between two Si plates with Si3N4 thin films of 200nm thickness using a sealant compatible for ultra high vacuum.We used this cell to measure Fe 2p soft x-ray absorption and emission measurement of a stable and dense (-10mM) myoglobin.3.Development of a sample scanning system to reduce radiation damageWe have developed a sample scanning system using the solution cell. However, an opening area toward soft x-rays required for control of a sample position and the opening area restricted for a vacuum-proof did not suit well, so we have given up the scanning of the sample position during measurements. Instead, we have developed a bulk sensitive spectrometer, a high energy photoemission spectrometer, to place a solution sample in a low vacuum.