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基于同步辐射XAFS方法的离子液体研究及BL14W1光束线站QXAFS方法的实现
Alternative TitleStudy of Ionic Liquids based on XAFS spectra and QXAFS method at BL14W1 beamline
邹杨
Subtype博士
Thesis Advisor徐洪杰
2009-05-26
Degree Grantor中国科学院上海应用物理研究所
Place of Conferral上海应用物理研究所
Keyword同步辐射 光束线 Bl14w1 X射线吸收精细结构谱 快速x射线吸收精细结构谱 离子液体 原位
Abstract自第一台同步辐射光源兴建以来,同步辐射技术已经成为科学研究上的一门重要的实验技术。随着同步辐射技术的发展,X射线吸收精细结构谱(XAFS)方法也得到了快速发展。发展新的XAFS实验技术,利用新的实验技术研究新型材料已经成为XAFS方法发展的重要方向。 上海同步辐射光源是国内自主创新建造的第一台第三代同步辐射光源,XAFS光束线站(名称为BL14W1)是首批七条线站之一。BL14W1光束线站的主要特点是使用了一个38极的Wiggler(扭摆器)作为光源,光通量很高,可达1013光子/秒/0.1%带宽。如何利用BL14W1光束线站的已有的设计条件实现新的XAFS方法也是优化BL14W1光束线站性能的重要问题之一。 QXAFS方法做为一种可以同普通XAFS方法兼容硬件系统的实验方法成为BL14W1光束线站发展新方法的首选目标。本论文的第一部分主要讨论了QXAFS方法在上海同步辐射装置BL14W1光束线站的实现过程,文中主要介绍了以下几个方面:(1)QXAFS方法的可行性探讨和设计;(2)与QXAFS方法有关的硬件系统的测试,其中包括双晶单色仪、气体电离室、电流放大器、ADC等硬件;(3)基于Labview的QXAFS方法软件系统的实现,其中的困难点在于与EPICS系统的通讯工作,软件系统主要包括如下几个部分:文件存储部分,与EPICS通讯的DSC模块部分、ADC初始化部分、数据获取部分、数据处理部分;(4)QXAFS方法实现后的QXAFS谱的测试结果与分析;(5)QXAFS方法信噪比和分辨率的优化。一系列的测试工作表明,上海同步辐射装置BL14W1光束线站已成功实现QXAFS方法,这也表明BL14W1光束线站将能够开展更加丰富的科学研究工作。 论文的第二部分主要应用同步辐射XAFS方法及上述的QXAFS方法开展了对于一种新型的热点材料——室温离子液体的研究工作,此种新型的热点材料拥有许多优异的物理化学性质:低的蒸气压、宽的液态范围、宽的电化学窗口以及高的电导率等,在诸如替代溶剂、电化学、有机化学合成等诸多工业有着非常广泛的应用潜力。本论文第二部分的研究工作包括以下内容: (1)利用北京BSRF和合肥NSRL同步辐射装置的XAFS光束线站开展了 [ChCl]-[ZnCl2]类型离子液体的研究工作,此种离子液体价格低廉,在萃取及金属电镀等工业上有着很大的应用潜力:本文对于不同x(ZnCl2)摩尔百分含量的[ChCl]-[ZnCl2]离子液体的熔化转变焓和Zn元素的近邻结构参数进行了分析;在此种类型的离子液体中,Zn的种态主要取决于x(ZnCl2)的摩尔百分含量,当x(ZnCl2)超过0.667时,发现一种新的Zn物种——Cl-Zn-Cl离子对出现在离子液体中,在x(ZnCl2)超过0.714时,此种新的Zn物种占据了主要地位并进而影响到了离子液体的性质。 (2)利用上海同步辐射装置BL14W1光束线站的QXAFS方法开展了 [Bmim]19-[FeCl3]类型离子液体在受辐照情况下的原位研究工作,此种含Fe基的离子液体在辐射化学、核废料处理、催化剂、萃取及金属电镀等工业上有着很大的应用潜力:[Bmim]19-[FeCl3]类型离子液体在受到辐照的情况下,其中的Fe(Ⅲ)会被还原为Fe(Ⅱ),本文应用同步辐射QXAFS方法对于其中的Fe物种的还原进行了原位观测。实验中观测到了Fe元素的XAFS谱的吸收边位置、边前峰高度、Fe-Cl键的键长以及Fe原子的配位数随照射时间有规律地变化;另外,随照射时间的变化,还观测到了样品的质量有规律地损失。为此,本文提出了[Bmim]19-[FeCl3]类型的离子液体在受到X射线辐照时其反应发生的机理。 (3)利用上海同步辐射装置BL14W1光束线站开展了[Bmim]Br离子液体的研究工作,此种阴离子为单个原子的离子液体对于研究离子液体中阴阳离子之间的作用力及结合方式有着很重要的意义:本文对比了纯的[Bmim]Br离子液体与[Bmim]Br-[Bmim][BF4]离子液体混合物中Br元素XAFS谱的变化情况。研究结果表明,在[Bmim]Br-[Bmim][BF4]混合物中,Br物种受到了周围环境更大的影响,其所带的负电荷更多地转移到了周围的阳离子当中。
Other AbstractThirty years have pasted since the first synchrotron radiation facility was completed. Synchrotron radiation techniques are powerful techniques for scientific researches now. XAFS technique is one of the most important synchrotron radiation techniques. Developing new method of XAFS technique is important for researches of novel materials. Shanghai synchrotron radiation facility (SSRF) is a third-generation light source, which is the first one in China. XAFS beamline (BL14W1) is one of the first seven beamlines. A wiggler was installed at BL14W1 beamline for high photon flux. Developing new XAFS method based on current instrumentations of BL14W1 beamline is very important for beamline researches. QXAFS method is a time-resolved method which is compatible with conventional XAFS method about instrumentations. The first part of this thesis discusses QXAFS method at BL14W1 beamline. The main content of this part is listed in the followed: (1) Design of QXAFS method at BL14W1 beamline; (2) Instrumentations for QXAFS method at BL14W1 beamline; (3) Program for QXAFS data acquisition system based on Labview; (4) Test and analysis of QXAFS spectra; (5) Optimizing of resolution and signal-to-noise ration for QXAFS method. The testing results indicate that QXAFS method has been achieved at BL14W1 beamline in SSRF. The second part of this thesis discusses some researches on Room Temperature Ionic Liquids (RTILs) by XAFS method. RTILs possess many desirable chemical and physical properties, such as good solubility, large liquid temperature ranges, negligible vapor pressure, high ionic conductivities and wide electrochemical window. RTILs have been utilised as clean solvents and catalysts for green chemistry and as electrolytes for batteries, photochemistry and electrosynthesis. The work is listed in the followed: (1) Components and structure of ionic liquid [ChCl]-[ZnCl2] in different ChCl:ZnCl2 ratios were investigated using XAFS technique in BSRF and NSRL. [ChCl]-[ZnCl2] ionic liquid are easy to prepare and low in cost, which is a potential material in Electrodeposition and extraction industry. The possible forms and structures of Zn species in the ionic liquids were analyzed according to the coordination number. XAFS and DSC (Differential scanning calorimetry) analysis imply that besides ZnCl3- and Zn2Cl5- anions, the Cl-Zn-Cl ion-pair is a main species in the ionic liquid at higher percentage of x(ZnCl2). This newly discovered Zn species has substantial influence on the properties of the ionic liquid. (2) An in-situ investigation when [Bmim]19-[FeCl3] RTIL was irradiated by X-ray was developed using QXAFS method at BL14W1 beamline in SSRF. When [Bmim]19-[FeCl3] is irradiated by X-ray, Fe(Ⅲ) is reduced to Fe(Ⅱ). QXAFS spectra changed regularly with irradiated time. Mass loss of this RTIL is observed in the experiment. A mechanism of reaction when [Bmim]19-[FeCl3] is irradiated by X-ray is demonstrated in this thesis. (3) A research work about [Bmim]Br RTIL was developed using XAFS method at BL14W1 beamline in SSRF. XAFS spectra are measured in pure [Bmim]Br RTIL and mixture of [Bmim]Br and [Bmim] [BF4] RTIL. The results indicate that environment around Br- anion has a strong influence on Br- anion. Charge transfer between Br- anion and cation is stronger in the mixture of [Bmim]Br-[Bmim] [BF4] RTIL than the pure [Bmim]Br RTIL.
Pages160
Language中文
Document Type学位论文
Identifierhttp://ir.sinap.ac.cn/handle/331007/7274
Collection中科院上海应用物理研究所2004-2010年
Recommended Citation
GB/T 7714
邹杨. 基于同步辐射XAFS方法的离子液体研究及BL14W1光束线站QXAFS方法的实现[D]. 上海应用物理研究所. 中国科学院上海应用物理研究所,2009.
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