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

• 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
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18310073/
• 关键词: Synchrotron Radiation X-ray; Single Crystal Structure Analysis; Charge Density Analysis; Molecular Conductor; Charge Ordering; Wigner Crystallization; Charge Density Wave; 雷荷秩序

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.

同步辐射（SR）X射线在材料科学研究中的应用越来越多。在本项目中，我们利用SR X射线衍射方法对新型分子晶体中的电子态进行了测定，高温下的稀薄电子气系统由于电子间的库仑排斥作用，具有较大的动能，因此是均匀的。在极低的温度下，该系统将倾向于冷凝并形成不均匀的团块，正如20世纪30年代早期的理论预测那样。由于这些团块带有负电荷，它们形成了一种结构，在空间定位中它们试图避免彼此。我们称这种现象为维格纳结晶。分子导体（DI-DCNQI）_2Ag即使在室温下也是绝缘的。在220 K以下，Hiraki和Kanoda利用核磁共振技术提出了DCNQI分子上电荷有序（CO）的4k_F Wigner晶体类型。这种CO基态是由Seo，et.电子晶体在真实的固体中是否（或如何）稳定是非常有趣的。使用SR的单晶X射线衍射测量在PF，KEK进行。根据结构分析结果，在基态下双层结构不仅由电荷有序化柱体组成，而且由DCNQI柱体之间的几何挫阻引起的单调电荷二聚化柱体组成。尽管这些复杂的序参数，这种电荷有序结构被认为是一个维格纳晶体引起的柱间库仑排斥。这是对3D电子晶体的首次直接观察。此外，我们在项目期间还研究了几种分子材料的电子态。

项目成果

Pressure-Induced Metal-Semiconductor-Metal Transitions in an MMX-Chain Complex, Pt2(C2H5CS2)4I

MMX 链复合物中压力诱导的金属-半导体-金属转变，Pt2(C2H5CS2)4I

• 发表时间: 2006
• 期刊: European Journal of Inorganic Chemistry
• 影响因子: 2.3
• 作者: A.Kobayashi;Y.Wakabayashi;H.Sawa;et al.
• 通讯作者: et al.

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

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

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

• 发表时间: 2007
• 作者: 垣内徹;土岐睦;赤田美佐保;澤博;谷垣勝己;八木ケ谷謙一;高木英典;Nita Dragoe;村田理尚;村田靖次郎;小松紘一
• 通讯作者: 小松紘一

Iron Vacancy Ordered Y_Fe2O3(001) Epitaxial Fims : The Crystal Structure and Electrical Resistivity

铁空位有序Y_Fe2O3(001)外延膜:晶体结构和电阻率

• 发表时间: 2006
• 期刊: J. Phys. Soc. Jpn. 75(5)
• 作者: H. Yanagihara;M. Hasegawa;E. Kita;Y. Wakabayashi;H. Sawa;K. Siratori
• 通讯作者: K. Siratori

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