权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Dispersive-Type Angle-Resolved Inverse Photoemission Spectrometer and Unoccupied Electronic Structure of Solids

色散型角分辨逆光电发射光谱仪与固体的空位电子结构

基本信息

批准号：
63460024
负责人：
TAKAHASHI Takashi
金额：
$ 3.71万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

1. A new electron gun with high-current density for use of inverse photoemission measurement has been designed. The electron gun has a BaO dispenser cathode as an electron emitter and a four electron-lense system to collimate the electron beam. It can be operated under ultrahigh vacuum (10^<-10>Torr) and gives 1 to 2 muA at the energy of 10 - 20 eV.2. Two types of novel superconductors were studied with the newly designed electron gun at the constant-photon-energy mode.(1) Angle-integrated and angle-resolved inverse photoemission spectra of cuprate high-Tc superconductors were measured. The experimental results show that doping of carriers produces new electronic states in the charge-transfer gap in the insulator instead of shifting the Fermi level. It was also found that the gap states consist of two dispersive bands crossing the Fermi level.(2) An inverse photoemission measurement on K^^3C^^<60> shows that doping of alkali-metals into C^^<60> cause a non-rigid filling of the LUMO band, leaving a pseudo-gap at the Fermi level.3. A new XUV spectrometer with high efficiency has been designed. The spectrometer is basically a non-Roland type grazing incidence spectrometer, designed for energy-range of 20 - 100 eV. An incident light at first collected with a large toroidal mirror then enters a 1/1200 grating for dispersing. The spectrometer has been tested with the He I resonance line as a reference and was found to give a satisfactory capability for dispersing-type inverse photoemission measurement.

1. 设计了一种新型的大电流密度电子枪，用于逆光电测量。电子枪具有一个BaO分配器阴极作为电子发射器和一个四电子透镜系统来准直电子束。它可以在超高真空（10^<-10>Torr）下工作，能量为10 - 20 ev，功率为1至2 muA。用新设计的电子枪在恒定光子-能量模式下研究了两种新型超导体。(1)测量了铜高tc超导体的角积分和角分辨逆发射光谱。实验结果表明，载流子的掺杂在绝缘体的电荷转移隙中产生新的电子态，而不是使费米能级发生位移。还发现，间隙态由两个色散带组成，穿越费米能级。(2)对K^^3C^^<60>的逆光电发射测量表明，在C^^<60>中掺杂碱金属导致LUMO带的非刚性填充，在费米能级上留下伪隙。设计了一种新型高效XUV光谱仪。该光谱仪基本为非罗兰型掠入射光谱仪，设计用于20 - 100 eV的能量范围。入射光首先用一个大的环形反射镜收集，然后进入1/1200光栅进行分散。以He - 1共振谱线为基准对该光谱仪进行了测试，结果表明该光谱仪具有较好的散射型逆光电发射测量能力。