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THREE DIMENSIONAL MEASUREMENT OF ELECTRONIC STRUCTURE

电子结构的三维测量

基本信息

批准号：
04402008
负责人：
SUGA Shigemasa
金额：
$ 15.81万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

The purpose of this project is to improve the spherical mirror analyzer and to measure the electronic energy band quickly using this analyzer. This analyzer can display the angular distribution of photoelectrons directly on the screen, which means we can observe the shape of cross section of band structure or Fermi surface directly.In order to measure the band structure efficiently we made an analyzer with a wide acceptance cone of <plus-minus>60 degrees. The detector was also changed to CCD camera which can measure at high count rate. A vacuum chamber was built to measure efficiently. To overcome the conflict between the energy resolution and the angular resolution, a special grid was made of machinable ceramicThe study of electronic structure progressed extensively. In the study of the cross section of piband of graphite, clear structure was observed. We could discuss the symmetry of the initial state because we used linearly polarized lignt. The asymmetry among Brillouin Zones was found and analyzed theoretically. A new idea of "photoemissaion structure factor" introduced by tight-binding calculation explained well the observed asymmetries. A discussion of these asymmetries is difficult inconventional measurements, and the importance of two-dimensional measurement was emphasized. Transition-metal dichalcogenides were also studied. The patterns for 1T-TaS2 at resonance photon energy showed a completely different pattern from others. This is the first observation of the angular distribution of resonant photoemission, and showed a way to study its process in detail.

本项目的目的是改进球面镜分析仪，并利用该分析仪快速测量电子能带。该分析仪可以直接在屏幕上显示光电子的角分布，这意味着我们可以直接观察能带结构或费米面的横截面形状。为了有效地测量能带结构，我们制作了宽接受锥<正负>60度的分析仪。检测器也改为CCD相机，可以进行高计数率测量。建造真空室是为了有效测量。为了克服能量分辨率和角度分辨率之间的冲突，由可加工陶瓷制成的特殊网格电子结构的研究取得了广泛进展。在对石墨管带横截面的研究中，观察到了清晰的结构。我们可以讨论初始状态的对称性，因为我们使用了线偏振光。发现并从理论上分析了布里渊区之间的不对称性。紧束缚计算引入的“光电发射结构因子”的新思想很好地解释了观察到的不对称性。对这些不对称性的讨论在传统测量中是困难的，并且强调了二维测量的重要性。还研究了过渡金属二硫属化物。 1T-TaS2 在共振光子能量下的模式显示出与其他模式完全不同的模式。这是对共振光发射角分布的首次观察，并展示了一种详细研究其过程的方法。