己烯在Ru(1010)表面价带电子特性研究

在200K以下己烯(C6H12)可以在Ru(101珔0)表面上以分子状态稳定吸附.偏振角分辨紫外光电子谱(ARUPS)结果表明,己烯分子在垂直于衬底表面并沿衬底表面<12珔10>晶向的平面内,己烯分子的轴向沿<12珔10>晶向倾斜.随着衬底温度的提高,到200K以上,己烯分解生成新的碳氢化合物.己烯分解后,πCH分子轨道能级向高结合能方向移动了0.2eV,同时己烯中C的1s能级向低结合能方向移动了0.3eV.     

乙烯在Ru(1010)表面价带电子特性研究

在200K以下乙烯(C2H4)可以在Ru(1010)表面上以分子状态稳定吸附,200K以上乙烯发生了脱氢分解反应生成乙炔(C2H2).乙烯分解生成乙炔后,σCC和σCH分子轨道能级向高结合能方向分别移动了0.5和1.1 eV.偏振角分辨紫外光电子谱(ARUPS)结果表明:在Ru(1010)表面上,乙烯和脱氢反应后生成的乙炔分子的C-C键轴都不平行于表面,而是沿表面(0001)晶向倾斜.     

C2H2在Ru(1010)表面上的分子轨道对称性

利用角分辨紫外光电子能谱对低温下（160 K）乙炔（C2H2）气体在Ru()表面的吸附 进行了研究.实验结果表明：乙炔的C-C轴并不平行于衬底表面, C-C轴在<0001>晶向和表 面法线组成的平面内有一定的倾斜.与气相乙炔分子不同,在Ru()表面吸附的乙炔分子的C-H 轴不是沿C-C轴向.     

用同步辐射光研究CO在Cs/Ru(100)表面的吸附

(CO+Cs)/Ru(1010)共吸附的体系中,CO分子由于受CS原子强烈影响,分子轨道发生重新杂化组合.CO分子原来在清洁Ru(1010)表面上结合能位于7.5eV处相重叠的5σ和1π轨道对应谱峰分裂为两峰,结合能分别位于6.3和7.8eV处.其中6.3eV处的谱峰来自CO分子1π轨道的一支,它显示出该分子轨道沿衬底<0001>晶向的镜面反对称性.CO分子1π轨道的另一支和5σ轨道在结合能7.8eV处相重叠.     

C_2H_2在Ru(10■0)表面上的分子轨道对称性

利用角分辨紫外光电子能谱对低温下（160 K）乙炔（C_2H_2）气体在Ru(10■0)表面的吸附进行了研究.实验结果表明：乙炔的C-C轴并不平行于衬底表面, C-C轴在<0001>晶向和表面法线组成的平面内有一定的倾斜.与气相乙炔分子不同,在Ru(10■0)表面吸附的乙炔分子的C-H轴不是沿C-C轴向.     

K/Ru(100)表面上的CO-4a_1轨道对称性确定

用同步辐射角分辨偏振紫外光电子谱对K/Ru( 10 10 )面上吸附的CO分子轨道的对称性测量发现 :结合能在 11.2eV的CO - 4a1( 4σ)分子轨道对s偏振光 (在沿〈12 10〉的入射面 )是禁戒的 .结果表明由于K的强烈影响 ,CO的分子轨道重新排列 (sp2 杂化 ) .依据选择定则和分子轨道的对称性说明 ,sp2 再杂化的CO分子吸附的桥位取向是 <12 10 >晶向     

K/Ru(10(1-)0)表面上的CO-4a1轨道对称性确定

用同步辐射角分辨偏振紫外光电子谱对K/Ru(10(1-)0)面上吸附的CO分子轨道的对称性测量发现:结合能在11.2eV的CO-4a1(4σ)分子轨道对s偏振光(在沿<1(2-)10>的入射面)是禁戒的.结果表明由于K的强烈影响,CO的分子轨道重新排列(sp2杂化).依据选择定则和分子轨道的对称性说明,sp2再杂化的CO分子吸附的桥位取向是<1(2-)10>晶向.     

FeO/Pt(111)与FeO2/Pt(111)的几何、电子结构及表面氧活性的第一性原理研究

采用密度泛函理论系统研究了超薄氧化物膜/金属体系FeO/Pt和FeO₂/Pt及其表面不同区域(FCC,HCP和TOP)的几何结构、电子性质及氧的活性.研究发现,表面O-Fe高度差δ_z作为一个重要的特征结构参数直接影响局域表面静电势和表面氧的结合能: δ_z越大,静电势越大,氧的结合能越弱.计算发现,在FeO/Pt体系中,δ_z顺序为FCC > HCP > TOP,而FeO₂/Pt中是FCC > TOP > HCP.此外,在FeO/Pt中,电荷转移方向是从氧化物膜到衬底,Fe的表观价态为+2.36,表面功函较纯Pt(111)的变化可忽略; 而FeO₂/Pt中,电荷转移的方向是从衬底到氧化物,Fe的表观价态为+2.95,表面功函较纯Pt增加1.24 eV.进一步分析了电荷转移和表面偶极对电子性质的作用机制.这些研究结果对于认识超薄氧化物薄膜对表面几何结构、电子性质、表面氧活性的调制具有重要的启示意义.     

银(110)表面苝有序薄膜电子态的研究

运用紫外光电子能谱(UPS)和低能电子衍射(LEED)技术,对银(110)表面上有机分子苝（perylene）的生长进行了研究.有机分子价带的4个特征峰分别位于费米能级以下3.5、4.8、6.4和8.5 eV处.当有机薄膜约为单分子层(厚度为0.3 nm)时, 苝在银(110)表面上形成C(6×2)的有序结构.角分辨紫外光电子能谱(ARUSP)的测量显示:在界面处的苝分子平面平行于衬底.苝在银(110)表面稳定性很高,随着对衬底加热，有机材料发生脱附,在140 ℃以下没有观察到分解现象.     

Fluorescein有机薄膜在Ag(110)面上的生长研究

利用紫外光电子能谱(UPS)对在Ag(110)表面上荧光素(fluorescein)的生长进行研究. 研究表明, 与fluorescein分子轨道有关的4个特征峰分别位于费米能级以下2.70, 3.80, 7.40和9.80 eV处. 角分辨紫外光电子能谱(ARUPS)测量结果表明, fluorescein分子的三苯环平面平行衬底平面, 分子的C=O轨道轴向接近于[1-10]晶向.     

COT-H在金属Ru表面上沉积的光电子能谱分析

采用紫外光电子能谱（UPS），分析了不对称四苯基四苯乙炔基环辛四烯（COT H）有机发光材料与金属之间的界面电子结构，研究了在金属/COT H界面上的逸出功变化.UPS谱中位于费米能级以下5.6、7.9和10.2 eV处的三个谱峰分别来自于COT H材料中苯环的πCC、σCC和σCH轨道.位于3.8 eV处的谱峰反映了八个苯环聚合后具有π轨道特性的C－C键.从UPS谱图中可以看到， COT H材料的最高占有态（HOS：highest occupied state）位于费米能级以下1.8 eV处.COT H材料的逸出功只有3.2 eV，比清洁Ru表面的逸出功小1.0 eV.角分辨紫外光电子能谱（ARUPS）的结果表明,组成COT H分子应该近似平行于衬底表面.     

Studies on the Valence Band of Ethylene (C2 H4) on Fu ( ) Surface

The ethylene(C2H4)absorbs in molecular state on Ru (1010) surface stably below 200K. The dehydrogenated of ethylene occurs at 200K. The main product of the dehydrogenation of the absorbed ethylene is the acetylene (C2H2). After the dehydrogenation of the absorbed ethylene, the binding energies ofσCCandσCHbond have an increase of 0.5 and 1.1eV respectively. The C-C bonds of both ethylene and acetylene tilt in <0001> azimuth.     

CO在Cs/Ru(1010)表面上吸附的ARUPS研究

CO adsorption on Ru(100) and Cs/Ru(10O) surfaces has been investigated using ARUPS, at low temperature 150K. The 5σ+1π and 4σ levels of CO molecule were　found in angle-rcsolved UP spectra showing that CO is in molecular adsorption states on clean and Cs precovercd Ru(1010). The dependence of CO 4σ intensity on incident angle suggests that adsorbed CO stands upright on clean Ru(1010) surface; But adsorbed CO, with a short-range interaction with Cs atom [15], does not stand upright and tilts in <1210> azimuth on a Cs-precovered Ru(1010) surface.     

Electronic delocalization in discotic liquid crystals: a joint experimental and theoretical study

Discotic liquid crystals emerge as very attractive materials for organic-based (opto)electronics as they allow efficient charge and energy transport along self-organized molecular columns. Here, angle-resolved photoelectron spectroscopy (ARUPS) is used to investigate the electronic structure and supramolecular organization of the discotic molecule, hexakis(hexylthio)diquinoxalino[2,3-a:2',3'-c]phenazine, deposited on graphite. The ARUPS data reveal significant changes in the electronic properties when going from disordered to columnar phases, the main feature being a decrease in ionization potential by 1.8 eV following the appearance of new electronic states at low binding energy. This evolution is rationalized by quantum-chemical calculations performed on model stacks containing from two to six molecules, which illustrate the formation of a quasi-band structure with Bloch-like orbitals delocalized over several molecules in the column. The ARUPS data also point to an energy dispersion of the upper pi-bands in the columns by some 1.1 eV, therefore highlighting the strongly delocalized nature of the pi-electrons along the discotic stacks.     

Study on the interaction between tetracene and Cu(110) surface

The electronic structure of tetracene on Cu (110) surface has been studied by using ultraviolet photoemission spectroscopy (UPS). The emission features from the organic molecule are located from 1 to 10 eV below the Fermi level, and they shift in binding energy with increasing the coverage of the organic material. For the surface with multilayer of tetracene, six well-resolved features were found at 1.90, 3.40, 4.70, 5.95, 6.95, and 9.15 eV below the Fermi level, respectively. On the surface with a lower coverage of tetracene, angle-resolved UPS measurements suggest that the molecular plane is parallel to the substrate. Density functional theory calculation confirms the flat-lying adsorption mode and shows that the tetracene molecule prefers to be adsorbed on the long bridge site with its long axis in the [110] azimuth.     

K/Ru(10ī0)表面上的CO-4a1轨道对称性确定

用同步辐射角分辨偏振紫外光电子谱对Ｋ／Ｒｕ（１０１０）面上吸附分子轨道的对称性测量发现：结合能在１１、．２ｅＶ的ＣＯ－４ａ１（４σ）分子轨道对ｓ偏振光（在沿〈１２１０〉的人射面）是禁戒的。结果表明由于Ｋ的强烈影响,ＣＯ的分子轨道重新排列（ｓＰ＾２杂化）。依据选择定则和分子轨道的对称性６说明,ｓｐ＾２再杂化的ＣＯ分子吸附的桥位取向是〈１２１０〉晶向。     

Electronic structure of cluster assembled nanostructured TiO(2) by resonant photoemission at the Ti L(2,3) edge

The electronic structure of cluster assembled nanostructured TiO(2) thin films has been investigated by resonant photoemission experiments with photon energies across the Ti L(2,3) edge. The samples were produced by supersonic cluster beam deposition with a pulsed microplasma cluster source. The valence band shows resonance enhancements in the binding energy region between 4 and 8 eV, populated by O 2p and hybridized Ti 3d states, and in the region about 1 eV below the Fermi level associated with defects related Ti 3d states. The data show that in as-deposited films Ti atoms are mainly fully (sixfolds) coordinated to oxygen atoms in octahedral symmetry and only a small fraction is in a broken symmetry environment. Since resonant photoemission is closely linked to the local electronic and structural configurations around the Ti atom, it is possible to correlate the resonant photoemission intensity and lineshape with the presence of defects of the films and with the degree of hybridization between the titanium and oxygen atoms.