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

STUDY ON SURFACE AND INTERFACE ELECTRONIC STRUCTURE DERIVED FROM THE DESIGNED TWO-DIMENSIONAL LATTICE.

从设计的二维晶格导出的表面和界面电子结构的研究。

基本信息

批准号：
03804027
负责人：
EGAWA Chikashi
金额：
$ 1.15万
依托单位：
UTSUNOMIYA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

In order to measure the electronic states of f.c.c. iron thin-films epitaxially grown on a Rh(001) surface, we constructed an ultra-violet photon source consisted of an inlet system of purified helium and a compact and clean differential pumping unit aide by a turbo-molecular pump. The alignment of capillary tubes inserted in the discharge and differential parts enabled us to increase the intensity and stability of photon source and to measure the electronic states quickly.We have investigated the reactivity of f.c.c. iron thin-films toward the adsorption of hydrogen and the surface reaction between adsorbed hydrogen and ethylene molecule. In contrast to the results reported on b.c.c. iron single crystal surfaces, the bonding energy of hydrogen to iron single layer on the Rh(001) surface is greatly reduced and the hydrogen desorbs from the surface at the temperature as low as 200 K. With the increase in the thickness of iron films above two-monolayer, the desorption temperature is grad … More ually shifted to 300 K and the sticking probability is reduced to one-tenth. The result corresponds to that observed on f.c.c. iron thin-films on Cu(001) surface. For the reaction of adsorbed hydrogen and ethylene, two desorption peaks are observed at 120 Kand above 200 K without the formation of ethane molecule. The latter is derived from the dehydrogenation of ethyl intermediate which is produced by adding of one hydrogen atom to ethylene molecule. The reactivity and stability of ethyl intermediate is also dependent on the thickness of iron overlayer.We have studied the electronic states, particularly around Fermi level, by means of ultra-violet photoelectron spectroscopy. For the clean Rh(001) surface, the sharp photoemission due to d-band is observed at 0-3 eV below Fermi level. The electronic states of iron overlayers are obtained from the subtraction of the contribution of Rh substrate emission assuming the electron escape depth of 2.5 monolayer. The result shows the reduction of the Fermi level intensity in accordance with the shift toward to the lower binding energy for the first monolyer of iron thin-films. Further increase in the thickness of iron film induced the increase of the emission of Fermi level and the peaks at 1.5 and 3 eV. A new state close to the Fermi level appears at 8 ML. From these observations, it is turned out that the electronic structures of f.c.c. iron thin-films are closely related to their reactivity and surface structure. Less

为了测量 f.c.c. 的电子态。利用在 Rh(001) 表面外延生长的铁薄膜，我们构建了一个紫外光子源，该源由纯化氦气入口系统和涡轮分子泵辅助的紧凑、清洁的差动泵单元组成。插入放电和微分部分的毛细管的排列使我们能够提高光子源的强度和稳定性，并快速测量电子态。我们研究了 f.c.c. 的反应性。铁薄膜对氢的吸附以及吸附的氢与乙烯分子之间的表面反应。与 b.c.c. 报道的结果相反。在铁单晶表面，氢与Rh(001)表面铁单层的键能大大降低，氢在低至200 K的温度下从表面解吸。随着两单层以上铁膜厚度的增加，解吸温度逐渐移至300 K，粘附概率降低至十分之一。结果与 f.c.c. 上观察到的结果一致。 Cu(001)表面的铁薄膜。对于吸附氢和乙烯的反应，在120 K和200 K以上观察到两个解吸峰，没有形成乙烷分子。后者是由乙基中间体脱氢而得，该中间体是通过在乙烯分子上添加一个氢原子而产生的。乙基中间体的反应活性和稳定性也取决于铁覆盖层的厚度。我们通过紫外光电子能谱研究了电子态，特别是费米能级附近的电子态。对于干净的 Rh(001) 表面，在费米能级以下 0-3 eV 处观察到由于 d 带而产生的尖锐光电发射。假设电子逃逸深度为 2.5 单层，铁覆盖层的电子态是通过减去 Rh 底物发射的贡献而获得的。结果表明，铁薄膜的第一单分子的费米能级强度随着向较低结合能的转变而降低。铁膜厚度的进一步增加导致费米能级发射增加，并在1.5和3 eV处出现峰值。接近费米能级的新状态出现在 8 ML 处。从这些观察结果表明，f.c.c. 的电子结构。铁薄膜与其反应性和表面结构密切相关。较少的