THREE DIMENSIONAL MEASUREMENT OF ELECTRONIC STRUCTURE

本课题的目的是对球面反射镜分析仪进行改进，并利用该分析仪对电子能带进行快速测量。该分析器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截面形状。为了有效地测量能带结构，我们制作了一台&lt；正负&gt；60度宽接受锥的分析器。探测器也改成了能以高计数率进行测量的CCD摄像机。建立了真空室来进行有效的测量。为了克服能量分辨率和角分辨率之间的矛盾，人们用可加工陶瓷制作了一种特殊的网格，电子结构的研究取得了广泛的进展。在石墨管横截面的研究中，观察到了清晰的结构。我们可以讨论初始态的对称性，因为我们使用了线偏振光。发现了布里渊区之间的不对称性，并从理论上进行了分析。紧束缚计算中引入的“光致发射结构因子”概念很好地解释了观察到的不对称性。这些不对称性的讨论在传统测量中是困难的，并强调了二维测量的重要性。对过渡金属二卤化物也进行了研究。在共振光子能量下，1T-TaS_2的花样显示出与其他样品完全不同的花样。这是首次观测到共振光电子角分布，并提供了一种详细研究其过程的方法。

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.