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Development of high energy-resolution inverse photoemission spectroscopy

高能量分辨率反光电子能谱的发展

基本信息

批准号：
12440080
负责人：
MIZOKAWA Takashi
金额：
$ 9.92万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12440080/
关键词：
inverse photoemission spectroscopy off-plane Eagle mounting dispersion matching ultraviolet light parallel plate analyzer unoccupied state Cu oxides Ru oxides 真空紫外線分光電子線エネルギー分析器 off-plane eagle 型配置低次元遷移金属酸化物

项目摘要

It is highly important to study occupied and unoccupied states of electrons in order to understand electronic properties of solids. Photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES) are complementary to each other and very powerful experimental methods to study the electronic structure of solids. While PES directly observes the occupied states below the Fermi level, IPES observes the unoccupied states above the Fermi level. Energy resolution of 2 meV has been achieved for PES and, consequently detailed information of occupied states of solids has been obtained. On the other hands, since the energy resolution of IPES is about 200 meV, information of unoccupied states is considerably limited by the poor energy resolution. Understanding of high-Tc cuprates is one of the most challenging problems in the field of solid state physics. The lacking of information about unoccupied states prevents us from the full understanding of their electronic properties. We have developed high energy-resolution IPES technique in order to study unoccupied states of high-Tc cuprates. We made a new IPES machine based on two ideas to improve the energy resolution : off-plane Eagle mounting of the optical system and dispersion matching between incoming electron and outgoing photon. The off-plane Eagle mounting of the optical system has been completed by setting the diffraction grating, the detector, and the test sample. In order to achieve the dispersion matching between the incoming electron beam and outgoing photon, we have made the parallel plate electron source and have investigated whether the electron beam is obtained as expected. Since the parallel plate electron source cannot supply enough current on the sample to measure inverse photoemission spectra, the IPES system is still not completed yet. We will continue the effort to construct the IPES machine.

为了理解固体的电子性质，研究电子的占据态和非占据态是非常重要的。光电子能谱(PES)和逆光电子能谱(IPES)是相辅相成的研究固体电子结构的强有力的实验手段。当PES直接观察费米能级以下的占用态时，IPES观察费米能级以上的未占用态。PES的能量分辨率达到2 meV，从而获得了固体占据态的详细信息。另一方面，由于IPES的能量分辨率约为200 meV，较低的能量分辨率极大地限制了空态信息的获取。对高T_c铜酸盐的理解是固体物理学领域最具挑战性的问题之一。缺乏关于空态的信息使我们无法充分了解它们的电子性质。为了研究高T_c铜酸盐的空态，我们发展了高能量分辨率的电子能谱技术。为了提高系统的能量分辨率，我们基于两个方面的思想制作了一台新型的光电子能谱仪：光学系统的离面鹰贴装和入射电子与出射光子的色散匹配。通过对衍射栅、探测器和测试样品的安装，完成了光学系统的离面安装。为了实现入射电子束和出射光子之间的色散匹配，我们制作了平行板电子源，并研究了电子束的获得情况。由于平行板电子源不能在样品上提供足够的电流来测量反光电子能谱，IPES系统还没有完成。我们将继续努力建造IPES机器。