Quasielastic Neutron Scattering Investigations of Ionic Liquids and Comparison to Complementary Methods

离子液体的准弹性中子散射研究及与补充方法的比较

• 批准号: 29119877
• 负责人: Professor Dr. Rolf Hempelmann
• 金额: --
• 依托单位: Transfercenter Sustainable Electrochemistry
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/29119877?language=en
• 关键词: Quasielastic; Neutron; Scattering; Investigations; Ionic

Using our own cold neutron time-of-flight spectrometer FOCUS at the Swiss spallation source SINQ of the Paul-Scherrer-lnstitute in Villigen (Switzerland) we would like to perform systematically a series of quasielastic neutron scattering (QENS) experiments to elucidate the dynamics in ionic liquids on atomistic scales of space and time. As model system we suggest [N-alkyl-N-methyl-pyrrolidinium] bis-(trifluoromethylsulfonyl) imide with different alkyl chains. Since protons are the dominant scattering centers, QENS on these systems probes the cation dynamics. It is known from literature, and confirmed by a QENS test experiments, that the hydrogen atoms in the cation side chains perform localized rotational motions. In order to study the diffusional dynamics these side chains have to be deuterated, so the hydrogen atoms at the stiff cation backbone can be observed. From model-independent data evaluation the essential features of the dynamics will first be conceived. Afterwards the data evaluation will be done in terms of appropriate theoretical models, for instance the two-state-model, which could give insight into the kinetics of ion pair formation. At a later stage also QENS with polarized neutron and neutron polarization analysis is intended in order to distinguish between incoherent and coherent QENS and thus between single particle diffusion and collective diffusion.

在瑞士维利根的Paul-Scherrer研究所的瑞士散裂源SINQ上，我们利用自己的冷中子飞行时间谱仪Focus，系统地进行了一系列准弹性中子散射(QENS)实验，以阐明原子空间和时间尺度上离子液体的动力学。作为模型体系，我们提出了具有不同烷基链的[N-烷基-N-甲基-吡咯烷]双(三氟甲基磺酰基)亚胺。由于质子是主要的散射中心，因此这些系统上的量子能谱探测阳离子动力学。从文献中已知，并经QENS测试实验证实，阳离子侧链中的氢原子进行局域旋转运动。为了研究扩散动力学，必须对这些侧链进行氢化，这样才能观察到刚性阳离子骨架上的氢原子。从与模型无关的数据评估中，将首先构思动力学的基本特征。之后，将根据适当的理论模型进行数据评估，例如两态模型，该模型可以深入了解离子对形成的动力学。在后面的阶段，还打算用极化中子和中子极化分析来区分非相干和相干量子核子，从而区分单个粒子扩散和集体扩散。