Ag(110)表面吸附酞菁铜分子的紫外光电子谱研究

用紫外光电子能谱(UPS)研究了酞菁铜分子在Ag(110)单晶表面上的吸附，随着酞菁铜分子覆盖度增加，衬底Ag的3d电子信号逐渐减弱，在此能带区域出现两个新的谱峰，这两个与吸附有机分子轨道有关的谱峰的束缚能分别为4.45 和6.36 eV.随着覆盖度的增加，在结合能为1.51和9.20 eV处又出现了两个谱峰，它们同样来自吸附有机分子的轨道.随着覆盖度的继续增加，上述四个谱峰的强度逐渐增加，其能量位置均发生了明显的偏移.根据角分辨光电子能谱的实验结果，酞菁铜分子的分子平面基本与衬底表面平行.密度泛函理论计     

CO在有K沉积的W(100)面上吸附的角分辨紫外光电子能谱

在不同K覆盖度的W(100)面上吸附CO的Hel紫外光电子能谱研究表明:α和β态的CO由于K的影响,吸附状态发生改变,与CO分子态(α态)有关的5σ/1π分子轨道能级随K覆盖度的增加,结合能位置从8.6eV移到9.3eV,反映K出现后,衬底对α-CO分子反施的增强。在与CO分解态(β态)有关的谱峰位置上(结合能为5.5eV)出现两个离散的谱峰,一个在6.0eV左右,另一个在5.2eV左右。其中结合能在5.2eV左右的谱峰强度随K的覆盖度增加而增大,它的能量位置与O在K覆盖的W(100)面上吸附时的能级位置 关键词：     

tetracene分子在Ru(100)表面的吸附结构及其电子态研究

利用紫外光电子能谱(UPS)、角分辨紫外光电子能谱(ARUPS)和扫描隧道显微镜(STM)等方法研究了tetracene分子在Ru(100)表面上吸附的电子态,吸附位置和吸附取向.UPS实验显示,与tetracene分子有关的光电子谱峰在费米能级以下2.1,3.5,4.8,6.0,7.1和9.2eV处;ARUPS结果表明,tetracene分子的分子平面基本平行于衬底表面;从STM图像中可以看到tetracene分子的长轴沿[0001]和[1■10]两个晶向.基于密度泛函理论的从头算计算证实了上述结论.当分子长轴沿[0001]晶向时,分子中心位置在衬底表面的“短桥位”上,当分子长轴沿[1210]晶向时,分子中心位置在衬底表面的“四原子中心空位”上.     

tetracene 分子在Ru(1010)表面的吸附结构及其电子态研究

利用紫外光电子能谱(UPS)、角分辨紫外光电子能谱(ARUPS)和扫描隧道显微镜(STM)等方法研究了tetracene分子在Ru(1010)表面上吸附的电子态，吸附位置和吸附取向.UPS实验显示，与tetracene分子有关的光电子谱峰在费米能级以下2.1, 3.5, 4.8, 6.0, 7.1和9.2 eV处；ARUPS 结果表明，tetracene分子的分子平面基本平行于衬底表面；从STM图像中可以看到tetracene分子的长轴沿［0001］和［1210］两个晶向.基于密度泛函理论的从头算计算证实了上述结论.当分子长轴沿［0001］晶向时，分子中心位置在衬底表面的“短桥位”上，当分子长轴沿［1210］晶向时，分子中心位置在衬底表面的“四原子中心空位”上. 关键词： tetracene分子 Ru(1010)表面 吸附结构 吸附电子态     

苯并咪唑苝与金属Ag的界面电子结构研究

利用同步辐射光电子能谱实验技术考察了苯并咪唑苝(BZP)和Ag的界面形成过程与电子结构.单层覆盖度以下时，BZP分子与Ag有弱相互作用，在有机分子禁带中出现明显界面反应态，结合能位于0.9eV.单层铺满后，BZP分子呈现三维岛式生长，且与Ag的相互作用逐渐减弱，同时最高占据分子轨道由于终态效应逐渐向高结合能方向位移至体相结合能位置(2.3eV). Ag衬底上BZP分子的生长导致样品表面功函数减小，表明形成了表面偶极势(Δ=0.3eV)，且电子从有机分子向金属Ag偏移.最后，考察了BZP/Ag 关键词： 有机-金属界面 电子结构 光电子能谱 同步辐射     

用ARUPS研究在Cs/Ru(1010)面上的CO分子轨道对称性

用同步辐射角分辨紫外光电子能谱对CO与Cs在Ru(1010)面上共吸附的研究结果表明,由于Cs的强烈影响,CO的分子轨道重新排列.对应清洁表面上CO分子的(5σ+1π)轨道的7.5eV谱峰分裂成两个,分别处于6.3和7.8eV,6.3eV谱峰关于一个垂直于Ru(1010)面而平行于〈0001〉晶向的镜象面反对称性. 关键词：     

三萘基膦在Ag(110)面上沉积的紫外光电子能谱研究

利用紫外光电子能谱（UPS）对新型有机半导体三萘基膦（TNP）在金属Ag(110)表面上沉积生长及其电子性质等进行了研究.三萘基膦的价带谱峰分别位于费米能级以下38，63，93和110 eV处，其中，价带顶 (HOS)位于费米能级以下约25 eV处.清洁Ag(110)表面的功函数为43 eV.随着三萘基膦在Ag(110)表面的沉积，功函数减小到38 eV，并达到饱和.根据UPS的测量结果，给出了三萘基膦/Ag(110)界面的能带结构，且三萘基膦与衬底Ag之间呈弱相互作用行为. 关键词： 紫外光电子谱 价电子结构 功函数     

氯原子在Cu(111)表面的吸附结构和电子态

密度泛函理论(DFT)总能计算研究了不同覆盖度下氯原子在Cu(111)表面的吸附结构和表面电子态。计算结果表明,清洁Cu(111)表面自由能 为15.72 ,表面功函数φ为4.753eV。在1/4ML和1/3ML覆盖度下,每个氯原子在Cu(111)表面fcc谷位的吸附能分别等于3.278eV/atom和3.284eV/atom。在1/2ML覆盖度下,两个紧邻氯原子分别吸附于fcc和hcp谷位,氯原子的平均吸附能为2.631eV/atom。在1/3ML覆盖度下,fcc和hcp两个位置每个氯原子吸附能的差值约为2meV/atom,与正入射X光驻波实验结合蒙特卡罗方法得到结果(<10meV/atom)基本一致。在1/4ML、1/3ML和1/2ML覆盖度下,吸附后Cu(111)表面的功函数依次为5.263eV、5.275eV和5.851eV。吸附原子和衬底价轨道杂化形成的局域表面电子态位于费米能级以下约1.2eV、3.6eV和4.5eV等处。吸附能和电子结构的计算结果表明,氯原子间的直接作用和表面铜原子紧邻氯原子数目是决定表面结构的两个重要因素。     

有机半导体perylene和tetracene在Ag(110)表面上有序薄膜的结构与电子态研究

利用紫外光电子能谱(UPS)和低能电子衍射(LEED)对银(110)表面上perylene与tetracene的生长进行了研究.LEED的结果表明：一个分子单层的perylene在银(110)表面上会形成C(6×2)的有序结构；一个分子单层的tetracene，观察到的则是C(4×2)的有序结构.根据UPS的测量，与perylene分子轨道有关的4个特征峰分别位于Frimi能级以下35，48，64和85eV处，与tetracene分子轨道有关的4个特征峰的结合能分别为3．4，49，59和94eV.角分辨紫外光电子能谱(ARUPS)的测量表明，表面附近的perylene和tetracene分子平面平行于银衬底表面，tetracene分子的长轴可以确定沿［110］晶向. 关键词： 有机半导体材料 紫外光电子能谱 结构和电子结构     

CO分子与碱金属原子在Fe(110)表面上的相互作用

本文介绍了CO分子分别与K原子或Na原子在Fe(110)表面上共吸附的研究。角分辨率紫外光电子能谱(ARUPS)的结果表明,碱金属原子在Fe(110)表面上的存在,紫外光电子能谱中出现了结合能低于通常CO分子1π能级的新峰。该峰位于费密能级以下6.3eV处,是C0在碱金属影响下电子结构改变的结果。该峰的出现对应着CO分子处于C—O键明显减弱的状态。偏振紫外光电子能谱的研究表明:6.3eV处的谱峰联系的电子轨道有一个对称平面和一个反对称平面,分别平行于<001>晶向和<110>晶向。CO分子轨道的对称性不因 关键词：     

Adsorption of 1,3,5-Triphenylbenzene Molecules and Growth of Graphene Nanoflakes on Cu(100) Surface

Adsorption of 1,3,5-triphenylbenzene(TPB) molecules on Cu( 100) surface is studied using ultraviolet photoelectron spectroscopy(UPS) and density functional theory(DFT) calculations. Researches on the bottom-up fabrication of graphene nanoflakes(GNFs) with TPB as a precursor on the Cu(100) surface are carried out based on UPS and DFT calculations. Three emission features d, e and f originating from the TPB molecules are located at 3.095, 7.326 and 9.349 eV below the Fermi level, respectively. With the increase of TPB coverage on the Cu(100) substrate, the work function decreases due to the formation of inter facial dipoles and charge(electron)rearrangement at the TPB/Cu(100) interface. Upon the formation of GNFs, five emission characteristic peaks of g, h, i, j and k originating from the GNFs are located at 1.100, 3.529, 6.984, 8.465 and 9.606 eV below the Fermi level, respectively. Angle resolved ultraviolet photoelectron spectroscopy(ARUPS) and DFT calculations indicate that TPB molecules adopt a lying-down configuration with their molecular plane nearly parallel to the Cu(100) substrate at the monolayer stage. At the same time, the lying-down configuration for the GNFs on the Cu(100) surface is also unveiled by ARUPS and DFT calculations.     

Photoelectron spectroscopy from CO adsorbed on a Cu(111) surface

He II-ultraviolet photoelectron spectra (hv = 40.8 eV) from a carbon monoxide layer adsorbed on a Cu(111) surface exhibit two peaks at 8.5 and 11.6 eV below the Fermi level and a weaker maximum centered at about 13.5 eV. The emission from the Cu d-band is markedly suppressed after adsorption. The results are discussed in terms of the recent models for assigning the UPS peaks observed after adsorption of CO on transtion metals     

Interfacial electronic structure at a metal–phthalocyanine/graphene interface:Copper–phthalocyanine versus iron–phthalocyanine

The energy level alignment of CuPc and FePc on single-layer graphene/Ni(111)(SLG/Ni)substrate was investigated by using ultraviolet and X-ray photoelectron spectroscopy(UPS and XPS).The highest occupied molecular orbitals(HOMOs)in a thick layer of CuPc and FePc lie at 1.04 eV and 0.90 eV,respectively,below the Fermi level of the SLG/Ni substrate.Weak adsorbate–substrate interaction leads to negligible interfacial dipole at the CuPc/SLG/Ni interface,while a large interfacial dipole(0.20 eV)was observed in the case of FePc/SLG/Ni interface,due to strong adsorbate–substrate coupling.In addition,a new interfacial electronic feature was observed for the first time in the case of FePc on SLG/Ni substrate.This interfacial state can be attributed to a charge transfer from the SLG/Ni substrate to unoccupied orbitals of FePc.     

H2O interaction with clean and oxygen precovered Ni(110)

The interaction of water vapour with clean as well as with oxygen precovered Ni(110) surfaces was studied at 150 and 273 K, using UPS, ΔΦ, TDS, and ELS. The He(I) (He(II)) excited UPS indicate a molecular adsorption of H₂O on Ni(110) at 150 K, showing three water-induced peaks at 6.5, 9.5 and 12.2 eV below E_F (6.8, 9.4 and 12.7 eV below E_F). The dramatic decrease of the Ni d-band intensity at higher exposures, as well as the course of the work function change, demonstrates the formation of H₂O multilayers (ice). The observed energy shift of all water-induced UPS peaks relative to the Fermi level (ΔE_max = 1.5 eVat 200 L) with increasing coverage is related to extra-atomic relaxation effects. The activation energies of desorption were estimated as 14.9 and 17.3 kcal/mole. From the ELS measurements we conclude a great sensitivity of H₂O for electron beam induced dissociation. At 273 K water adsorbs on Ni(110) only in the presence of oxygen, with two peaks at 5.7 and 9.3 eV below E_F (He(II)), being interpreted as due to hydroxyl species (OH)^δ? on the surface. A kinetic model for the H₂O adsorption on oxygen precovered Ni(110) surfaces is proposed, and verified by a simple Monte Carlo calculation leading to the same dependence of the maximum amount of adsorbed H₂O on the oxygen precoverage as revealed by work function measurements. On heating, some of the (OH)^δ? recombines and desorbs as H₂O at ? 320 K, leaving behind an oxygen covered Ni surface.     

An electronspectroscopic study of adsorbate structure

The ultraviolet photoelectron spectra of xenon adsorbed on crystals of (100) nickel and (110) iron have been measured as a function of xenon coverage. It is shown that the total current in the xenon peaks is a measure of the xenon coverage but that the attenuation of the electrons from the metal substrate is dependent on the packing density of xenon on the surface. Previous measurements by Auger electron spectroscopy are compared and it is shown that the mean free path of 16 eV electrons from the d-bands of nickel and iron is 2.75 times that of 60 eV Auger electrons. The data allows the calculation according to a slab model of a mean thickness of a xenon monolayer. This is interpreted as a measure of the packing density of xenon localized on metal lattices of varying dimensions. The UPS spectrum for xenon on (110) iron shows a marked broadening of the xenon peaks as compared to (100) nickel. This is interpreted as due to variation in relaxation energy over adsorbate states on the iron surface arising from xenon atoms in offsite positions.     

An investigation of the adsorption of oxygen and oxygen containing species on platinum by photoelectron spectroscopy

It is shown that XPS can detect 0.01 monolayers of adsorbed carbon or oxygen and can identify the chemical state of the adsorbed atom(s). Two states of adsorbed oxygen were resolved by thermal desorption spectroscopy and by XPS. The O 1s binding energies (^FE_B) were 530.2 and 533 eV below the platinum Fermi level for the strongly and weakly adsorbed states respectively. (^FE_B) did not vary with coverage. The resulting apparent variation of (^VE_B), the vacuum level referenced value, is discussed in terms of a simple model for the work function Φ which was measured in situ. UPS indicated that the weakly adsorbed state is probably molecular, with levels at 6.1, 9.3, 10.4 and l2.4 eV below the Fermi level. The main change in the UPS spectra produced by the strongly adsorbed state was a reduction of a peak close to the Fermi level.     

Photoemission studies of H2S,H2 and S adsorbed on Ru(110): Evidence for an adsorbed SH species

H₂S, H₂ and S adsorbed on Ru(110) have been studied by angle-integrated ultraviolet photoemission (UPS) as part of a study of the effect of adsorbed sulfur, a common catalytic poison, on this Ru surface. For low exposures of H₂S at 80 K, the work function rises to a value 0.16 eV above that of clean Ru(110) while the associated UPS spectra (hν = 21.2 eV) exhibit features similar to those of H(ads) and S(ads) and different from those of molecular H₂S. We conclude that H₂S dissociates completely at low coverages on Ru(110) at 80 K. At intermediate exposures the work function drops and the UPS spectra show new features which are attributed to the presence of an adsorbed SH species. This appears to be the first direct observation of this surface complex. At higher exposures the work function saturates at a value 0.36 eV below the clean value; the UPS spectra change markedly and indicate the adsorption of molecular H₂S. Heating adsorbed H₂S leaves a stable layer of S(ads) on Ru(110). The surface with adsorbed sulfur strongly modifies the adsorption at 80 K of a number of molecules relative to the clean Ru(110) surface.