共查询到19条相似文献,搜索用时 765 毫秒
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利用同步辐射光电子能谱,研究了室温下在GaAs(100)表面上淀积的Mn的超薄膜的电子结构.实验发现,在θ<2ML的覆盖度下,Mn3d电子的能量态密度分布与体金属α-Mn差别很大当θ>2ML之后,便逐步接近α-Mn的体电子结构.这一结果可由Mn3d电子的自旋向上带和自旋向下带的交换分裂很好地解释.由此推断,当覆盖度θ<2ML时,在GaAs(100)表面上淀积的Mn的超薄膜具有磁有序结构
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本文用X射线光电子能谱(XPS),紫外光电子能谱(UPS),电子能量损失谱(EELS)和低能电子衍射(LEED)研究了O与预覆盖K的Ag(110)表面相互作用及其性质。在低覆盖度K下,发现有两种O的吸附态,经鉴别为溶解到表面下的O2-和表面上吸附的Ox-增加K的覆盖度,出现分子状态的吸附物O2δ-,它与表面下存在的K相联系。XPS和UPS均清楚地显示出对应于三种不同吸附态的光电子发射峰。Ag(110)表面预覆盖K后的粘滞系数大大增加。K和O的共吸附引起它们彼此向Ag(110)表面下的溶解。LEED实验结果表明,清洁Ag(110)表面覆盖单层K原子后衍射图形从(1×1)变到(1×2),再吸附O后表面吸附层结构变为(2×1)。另外,结合UPS和EELS测量初步考察了O/K/Ag(110)共吸附系统的电子结构。本文还提出了一个共吸附模型来解释这些现象。
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为了阐明Co原子在钼硫化态催化剂表面上的助催化作用,本文利用UPS,XPS和LEED,研究了Co-Mo催化剂活性相的层状硫化物半导体MoS2单晶边缘面区域的成分较高的表面以及离子溅射解理面上过渡金属Co的亚原子单层淀积过程。在覆盖度为某个亚原子单层时,表面上存在的与淀积上去的Co有关的界面态,改变了EF能级的钉扎位置(提高了0.30—0.35eV),使表面势垒下降,表面功函数减小。在EF附近电子结构的明显变化和LEED研究的结果表明,在MoS2表面的无序缺陷位置上,可能形成了有利于催化过程的Co-Mo-S类合金键型的活性相。
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用分步激发方法及偏振光技术,测定了锶的(5p3/2ns)1(n=13-21)及(5p3/2 nd)3(n=13-24)各自电离谱,在低于5p1/2电离限的(5p3/2ns)1态的实电子激发谱中,出现对应于(5p1/2ns)1及(5p1/2nd)1的畸变峰,畸变峰也出现于(5p3/2nd)3的实电子激发谱中。这说明(5pjns)(5pjnd)自电离系列间存在相互作用。
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用坩埚下降法(Bridgman)生长出了Bi离子掺杂的CdWO4单晶.测定了晶体不同部位的吸收光谱、发射光谱和X射线电子能谱(XPS).Bi离子的掺入引起CdWO4晶体的吸收边从345 nm红移到399 nm.在311 nm, 373 nm,808 nm和980 nm光的激发下,分别观测到中心波长为470 nm,528 nm,1078 nm和较弱的1504 nm四个不同发射带.Bi:CdWO4单晶的XPS谱分别与Bi2
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Bi离子
荧光光谱
X射线电子能谱
4单晶')" href="#">CdWO4单晶 相似文献
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高分辨率电子能量损失谱(HRFELS)能直接判定Al-GaAS(100)界面反应的生成物。本文结合X射线光电子能谱(XPS)的测量,采用HREELS来测量界面的禁带宽度,研究了Al-GaAs(100)(4×1)界面的形成过程。结果判定了室温下Al-GaAs(100)界面生成的为AlAs。而退火后,界面上生成AlCaAs合金。实验中还用低能电子衍射(LEED)观察了室温下Al在GaAs(100)(4×1)面上的淀积过程,发现随着Al淀积量的增加,表面是从无序到有序转化的。
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The room temperature growth mode and the interface reaction of Fe films on single crystalline ZnO(0 0 0 1) substrates prepared in ultra high vacuum (UHV) has been investigated by means of X-ray photoelectron and Auger electron spectroscopy (XPS, AES), low energy electron diffraction (LEED) and low energy ion scattering spectroscopy (LEIS). The results show that Fe grows in the pseudo layer-by-layer mode. At ambient temperature the deposited Fe film reduces the underlying ZnO single crystal resulting in FeO at the interface and metallic Zn, which partially diffuses into the remaining Fe overlayer. Annealing leads to a stepwise oxidation of the Fe to FeO (670 K) and Fe2O3 (820 K). The Fe2O3 mixes with the substrate resulting in two (1 1 1) oriented textures of a spinel phase found by electron backscatter diffraction analysis (EBSD). Fe-based spin-injection may play a vital role for ZnO-based spintronic devices. 相似文献
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The initial oxidation of Mg(0001) has been studied using AES (Auger electron spectroscopy), LEED (low energy electron diffraction), and EELS (electron energy loss spectroscopy). The oxidation proceeds through different stages; first oxygen atoms are incorporated to chemisorption sites below the top layer magnesium. This chemisorption phase is followed by the formation of an oxide layer. The oxide layer covers the Mg surface after an oxygen exposure of ~ 10 L O2. After this exposure the bulk-like MgO formation slowly increases the oxide thickness. The oxide layer formed for exposures up to ≤ 10 L O2 gives rise to a diffuse LEED pattern of the same symmetry as the original “clean” LEED pattern; the possibility of an epitaxial oxide formation at this stage is discussed. 相似文献
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LEED, AES, UPS and EELS have been used to observe the growth of thallium in the Stranski-Krastanov mode on copper(100). In the sub-monolayer range, thallium forms three commensurate ordered overlayer structures. The transition from the first overlayer structure to the second involves a transition from a one-dimensional to a two-dimensional structure. The resulting change in co-ordination number reduces the binding energy of the thallium 5d core levels and increases their width. 相似文献
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H. Papp 《Surface science》1983,129(1):205-218
The chemisorption of CO on Co(0001) has been investigated by LEED, UPS, EELS, Auger and sp measurements. CO is molecularly adsorbed on Co(0001) in the investigated temperature range from 100 to 450 K. This is deduced from the UPS and EELS results and the reversibility of the sp and LEED data. The isosteric heat of adsorption has a constant value of 128 kJ/mol up to a coverage of and drops then to about 96 kJ/mol. This coincides with the completion of a (√3 × √3)R30° overlayer structure and the formation of a (2√3 × 2√3)R30° CO overlayer which is fully developed at 100 K. 相似文献
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《Surface science》1987,182(3):545-556
The GaAs(110)-Sb system is studied with AES, EELS, LEED, ellipsometric spectroscopy and SEM. As indicated by EELS Sb atoms are adsorbed first on Ga sites. The AES spectra can be explained by assuming a simultaneous growth of multiple layers on top of a well ordered homogeneous first monolayer (MSM growth mode). The results of ellipsometric spectroscopy confirm the inhomogeneity of the Sb-film as proposed by the MSM mode. Desorption experiments and EELS demonstrate a strong chemical bonding between the first Sb monolayer and the substrate. 相似文献
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S.W. D′Souza J. Nayak M. Maniraj Abhishek Rai R.S. Dhaka S.R. Barman D.L. Schlagel T.A. Lograsso Aparna Chakrabarti 《Surface science》2012,606(3-4):130-136
Ni2MnGa(100) single crystal studied using low energy electron diffraction (LEED) and ultraviolet photoemission spectroscopy (UPS) exhibits interesting modification of the surface properties that are mainly influenced by surface composition as well as intrinsic effects. In the martensite phase, the LEED spot profiles show presence of an incommensurate modulation for the stoichiometric surface. In contrast, a commensurate modulation is observed for Mn-excess Ni–Mn–Ga surface. A pre-martensite phase is identified at the surface. Both the surface martensitic and pre-martensitic transition temperatures decrease as the Mn content increases. The UPS spectra in the austenite phase exhibit systematic change in shape as a function of surface composition that can be related to changes in the hybridization between Ni and Mn 3d states. The spectra in the martensite phase exhibit interesting modifications near the Fermi level, which has been compared to density of states calculated for a modulated structure by ab-initio density functional theory. Intrinsic surface properties dissimilar from the bulk are enhanced hysteresis width of the martensite transition and increased pre-martensitic transition temperature. 相似文献
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《Surface science》1986,172(1):174-182
The room temperature adsorption of CF3COOH, CH3COOH and CO on cleaved GaAs(110) surfaces has been studied by vibrational electron energy loss spectroscopy (HRELS), second derivative electron energy spectroscopy (ELS) and electron diffraction (LEED). CO does not adsorb on the GaAs surfaces in measurable quantities. Acetic acid CH3COOH is dissociatively adsorbed as an acetate bonded to Ga surface atoms with the split-off hydrogen on As surface atoms. The fluorated acid CF3COOH decomposes via an acetate intermediate CF3COO into active CF3 groups which adsorb on Ga surface atoms. The split-off hydrogen sticks to surface As atoms while the generated CO2 desorbs. The adsorption models are consistent with the LEED c(2×2) superstructure observed after saturated adsorption of both acids. 相似文献
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H.Y. Ho 《Surface science》2007,601(3):615-621
The initial growth and alloy formation of ultrathin Co films deposited on 1 ML Ni/Pt(1 1 1) were investigated by Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and ultraviolet photoelectron spectroscopy (UPS). A sequence of samples of dCo Co/1 ML Ni/Pt(1 1 1) (dCo = 1, 2, and 3 ML) were prepared at room temperature, and then heated up to investigate the diffusion process. The Co and Ni atoms intermix at lower annealing temperature, and Co-Ni intermixing layer diffuses into the Pt substrate to form Ni-Co-Pt alloys at higher annealing temperature. The diffusion temperatures are Co coverage dependent. The evolution of UPS with annealing temperatures also shows the formation of surface alloys. Some interesting LEED patterns of 1 ML Co/1 ML Ni/Pt(1 1 1) show the formation of ordered alloys at different annealing temperature ranges. Further studies in the Curie temperature and concentration analysis, show that the ordered alloys corresponding to different LEED patterns are NixCo1−xPt and NixCo1−xPt3. The relationship between the interface structure and magnetic properties was investigated. 相似文献