THREE DIMENSIONAL MEASUREMENT OF ELECTRONIC STRUCTURE

本课题的目的是对球镜分析仪进行改进，利用球镜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度分布，这意味着我们可以直接观察到带结构或费米面截面的形状。为了有效地测量波段结构，我们制作了一个宽接收锥<正负bbb60度的分析仪。探测器也改为CCD相机，以实现高计数率的测量。为了有效地测量，建立了一个真空室。为了克服能量分辨率和角分辨率之间的冲突，采用可加工陶瓷制作了一种特殊的网格。在石墨管带截面的研究中，观察到清晰的结构。我们可以讨论初始态的对称性因为我们用的是线偏振光。发现了布里渊带之间的不对称性，并进行了理论分析。由紧结合计算引入的“光电结构因子”的新概念很好地解释了观察到的不对称现象。讨论这些不对称在常规测量中是困难的，强调了二维测量的重要性。过渡金属二硫族化合物也进行了研究。在共振光子能量下，1T-TaS2的模式显示出与其他模式完全不同的模式。这是首次观测到共振光发射的角分布，并为详细研究其过程提供了一条途径。

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.