Direct Observation of Electron Density Distribution of the Molecular Orbital Detected by Synchrotron Radiation X-Pay Diffraction

同步辐射X-Pay衍射直接观察分子轨道电子密度分布

基本信息

批准号：
18310073
负责人：
SAWA Hiroshi
金额：
$ 10.65万
依托单位：
High Energy Accelerator Research Organization
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

The Synchrotron Radiation (SR) X-ray is finding increasing use in the study of material science. In this project, we utilized the SR X-ray diffraction methods for the determination of the electronic state in the novel molecular crystals.Rarefied electron gas system at high temperature is homogeneous due to the large kinetic energy compared to the Coulomb repulsion among electrons. At extreme low temperatures, the system will tend to condense and make uneven lumps, as theoretically predicted in the early 1930's. Since these lumps carry a negative charge, they form a structure where they try to avoid each other in the spatial positioning. We call this phenomenon the Wigner crystallization. A molecular conductor (DI-DCNQI)_2Ag is insulating even at room temperature. Below 220 K, Hiraki and Kanoda suggested that the 4k_F Wigner crystal type of charge order (CO) on DCNQI molecules by NMR technique. This CO ground state was theoretically predicted by Seo, et. al. It is very interesting whether (or how) the electron crystal is stable in the real solid. Single crystal x-ray diffraction measurements using SR were performed at PF, KEK. According to the result of the structural analysis, two-fold structure in ground state consists of not only charge ordering columns but also monotonic charge dimerized columns caused by geometrical frustration among DCNQI columns. In spite of these complicated order parameters, this charge ordered structure is regarded as a Wigner crystal caused by inter-column Coulomb repulsion. This is a first direct observation of the 3D electron crystal. Furthermore, we investigated the electronic state in several molecular materials during the term of project.

同步加速器辐射（SR）X射线正在发现材料科学研究的越来越多。在这个项目中，我们利用SR X射线衍射方法来测定新型分子晶体中电子状态的测定。与电子在电子中相比，由于具有较大的动能，因此在高温下进行了培养的电子气体系统是均匀的。在极高的温度下，正如1930年代初期所预测的那样，该系统将倾向于凝结并使肿块不均匀。由于这些团块带有负电荷，因此它们形成了一种结构，在空间定位中互相避免。我们将这种现象称为Wigner结晶。即使在室温下，分子导体（DI-DCNQI）_2AG也可以绝缘。低于220 K，Hiraki和Kanoda建议通过NMR技术在DCNQI分子上的4K_F晶体晶体类型的电荷顺序（CO）。从理论上讲，该CO基态由SEO等预测。 al。电子晶体在实际固体中是稳定的，这是非常有趣的。使用SR的单晶X射线衍射测量在PF，Kek进行。根据结构分析的结果，基态中的两个结构不仅包括电荷排序柱，而且还包括由DCNQI列之间的几何挫折引起的单调电荷二聚列。尽管有这些复杂的阶参数，但该电荷有序结构仍被认为是由柱间库仑拒绝引起的晶体晶体。这是对3D电子晶体的第一个直接观察。此外，我们在项目期限期间研究了几种分子材料的电子状态。

项目成果

期刊论文数量（0）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Correlation between crystal structures of CaAlSi with and without superlattice and superconduction properties

有超晶格和无超晶格的CaAlSi晶体结构与超导性能的相关性

DOI：
发表时间：
2006
期刊：
Phys. Rev. B 74
影响因子：
0
作者：
S.Kuroiwa;H.Sagayama;T.Kakiuchi;H.Sawa;et al.
通讯作者：
et al.

Two Types of Multistack Structures in MgB2-Type Superconductor CaAlSi

DOI：
10.1143/jpsj.75.043713
发表时间：
2006-04
期刊：
Journal of the Physical Society of Japan
影响因子：
1.7
作者：
H. Sagayama;Y. Wakabayashi;H. Sawa;T. Kamiyama;A. Hoshikawa;S. Harjo;K. Uozato;A. Ghosh;M. Tokunaga;T. Tamegai
通讯作者：
H. Sagayama;Y. Wakabayashi;H. Sawa;T. Kamiyama;A. Hoshikawa;S. Harjo;K. Uozato;A. Ghosh;M. Tokunaga;T. Tamegai

放射光X線回折によるガス内包フラーレンの構造物性研究

利用同步辐射X射线衍射研究气态内嵌富勒烯的结构性质