LnCu2O4(Ln=Gd,Nd)电子结构的XPS研究

用XPS测定了LnCu2O4(Ln=Gd, Nd)的内层和价层电子能谱,观察到LnCu2O4中稀土金属的3d电子结合能比相应的稀土金属简单氧化物的3d结合能低0.8～0.9 eV,而Cu的2p电子结合能比CuO的高0.4～0.5 eV,因此推断在LnCu2O4的Ln－O－Cu链中存在Cu→O→Ln电荷转移.XPS分析还表明LnCu2O4的Cu原子上有较低的电荷密度,但不存在混合价态.此外,通过比较价电子能谱,发现NdCu2O4的Ln 4f Cu 3d O 2p价带中心比GdCu2O4的价带中心向Fermi能级移近了3.4 eV,而且NdCu2O4的价带谱更窄.     

硅晶片上超薄氧化硅层厚度纳米尺寸效应的XPS研究

用X射线光电子能谱(XPS)测定了一系列厚度经过国际比对准确已知的硅晶片上的超薄(1.45nmd7.2nm)氧化硅膜的Si2p电子能谱和价带谱.结果表明:SiO2膜厚d2nm时,Si2p结合能最低,其原因可归结于此时光电离空穴既有来自SiO2中的原子极化对空穴的原子外弛豫,也有来自衬底Si的电荷移动对空穴的屏蔽(有效屏蔽距离大约是(2.5±0.6)nm);当d3nm时Si2p结合能增大,此时只有来自SiO2的原子外弛豫,d较小者的Si2p结合能较高.SiO2的价带电子结构也与其厚度纳米尺寸效应有关:当d2nm时价带中SiO2的O2p非成键电子峰的相对强度较强,O2p—Si3p和O2p—Si3s成键电子峰较弱.     

2-巯基苯骈噻唑与铜(Ⅱ)离子配位作用的XPS研究

XPS研究表明,2-巯基苯骈噻唑与铜(Ⅱ)的螫合物中除S→Cu配位作用外,还存在明显的Cu→配体反馈配位作用,从而增强了螫合物的稳定性。螫合物中铜的2p电子结合能与Cuo的接近,这反映铜离子是+2价,但它的Cu2P电子能谱缺乏摔激伴线。这是由于Cu与配体之间以共价键配位,当Cu2p电子被光电离后可发生完全的配体→铜电荷转移并导致→种终态。     

轻希土硫氰酸盐与2,3,11,12,-四苯基-1,4,7,10,13,16-六氧-2,11-十八环二烯配合物的合成及XPS研究

合成了六种轻希土硫氰酸盐与标题不饱和冠醚的新固体配合物,进行了元素分析,摩尔电导率、DTA、UV、IR和XPS等表征。对Ln(NCS)_3·L和Ln(NCS)_3的XPS研究中,得到它们组成原子芯能级电子(Ln3d_(5/2),Ols,Nls,S2p)的结合能信息;观察到除Y3d_(5/2)外Ln3d_(5/2)(Ln=La、Ce、Pr、Nd、和Sm)的伴峰结构,Ln3d_(5/2)结合能与原子序数呈线性关系,并推断类似化合物Pm3d_(5/2)结合能在1035eV附近.     

轻稀土氯化物与2,3,11,12-四苯基-1,4,7,10,13,16-六氧-2,11-十八环二烯配合物的合成及XPS研究

本工作合成了轻稀土氯化物与题目不饱和冠醚所形成的三种新的轻稀土配合物。元素分析数据说明稀土氯化物与配体的化学配比是1:1。我们着重对这些配合物进行了X射线光电子能谱研究,得到了组成原子芯能级电子(Ln 3d_(5/2),O 1s,C 1s,Cl 2p)的结合能变化信息。在LnCl_3·L和LnCl_3中观察到Ln 3d_(5/2)[Ln=Ce(Ⅲ),Pr(Ⅲ),Sm(Ⅲ)]的伴峰结构,其伴峰能前者分别为3.8和-4.2eV,后者为3.9,-4.5和-3.1eV。这是由于Cl 3p→Ln 4f电荷转移跃迁所引起的,铈属于“振起”(Shake-up)过程,镨和钐属于“振落”(Shake-down)过程。     

空穴掺杂对Li1-xCuVO4(x≤0.1)一维自旋链材料光谱性质的影响

采用固相烧结方法合成了部分Li+缺失的一维自旋链材料Li1-xCuVO4(x≤0.1). X射线衍射和Raman光谱分析结果表明, 所得材料属于正交晶系, 具有反尖晶石结构; Li+的缺失并未对材料的长程和短程结构具有明显的影响. X射线光电子能谱(XPS)研究结果表明, 空穴掺杂前后, O离子和V离子的价态并未随Li+缺失而发生改变, 仍然为-2价和+5价. 而Cu离子的2p53d10 L态向高结合能区发生了偏移, 说明在部分Cu2+上出现了空穴, 形成了Cu3+.     

N掺杂TiO_2光催化剂的微结构与吸光特性研究

以紫外可见漫反射光谱(UV-VIS-DRS)和X射线光电子能谱(XPS)分析和研究了四种方法制备的N掺杂TiO2光催化剂的结构,即水解法(N/TiO2-H)、氨热还原法(N/TiO2-A)、机械化学法(N/TiO2-M)和尿素热处理法(N/TiO2-T)等.结果表明,N/TiO2-H和N/TiO2-T两种催化剂在490 nm处有吸收带边,可见光激发途径是掺杂的N以填隙方式形成的杂质能级吸收电子发生的跃迁引起的;而N/TiO2-A和N/TiO2-M两种催化剂在整个可见光区域内具有可见光吸收,其对可见光的激发途径是掺杂N和氧空缺共同作用的结果.理论计算的N杂质能级位于价带上0.75 eV,与实验观察到的吸收带边结果十分吻合.XPS结果表明,几种催化剂的N1 s结合能位置都在399 eV附近,显示为填隙掺杂的N原子.填隙掺杂的N/TiO2,其Ti原子的2p结合能与未掺杂的TiO2相比增加了+0.3-+0.6 eV,而O1s电子的结合能增加了+0.2-+0.5eV,这是因为填隙的N原子夺取Ti和O的电子,Ti和O原子周围的电子密度降低了.电子能谱和吸光特性的研究都表明,掺杂的机理是在TiO2晶格内形成N原子的填隙.     

稀土掺杂La-Al-EU-1分子筛的合成与表征

在HMBr2-Na2O-Al2O3-SiO2-La2O3-H2O体系中,采用水热法合成了高结晶度的La-Al-EU-1分子筛。通过XRD,FT-IR,XPS,TG-DTG和UV-Vis DRS等手段对合成样品进行分析。结果表明:随着原始溶胶中镧的质量分数增加,La-Al-EU-1分子筛晶胞体积膨胀;FT-IR骨架振动频率向低波数方向移动,在约980 cm-1处出现Si-O-La对称伸缩振动谱带;在λ=245 nm分子筛骨架O原子的成键2p电子向骨架四配位的La原子的空d轨道的p-d跃迁产生的特征峰强度增强;La3d3/2和La3d5/2伴峰电子结合能比La2O3高1.0 eV,氧的O1s电子结合能比La2O3高1.1 eV,La3d和O1s的电子结合能同步向高能方向移动,导致La-O键共价性减少,电子云密度降低,La-O键长增加,证明了La原子已经进入了分子筛骨架,并以La3+离子四配位方式存在;当ωLa0.82%,n(SiO2)/n(Al2O3)=50~80时,晶化时间24~41 h,可以合成高结晶度的La-Al-EU-1分子筛。     

稀土冠醚配合物的XPS研究 Ⅰ.Ln(NO_3)_3·C_(14)H_(20)O_5和Ln(NO_3)_3·C_(20)H_(24)O_6的Ln 3d_(5/2)光电子能谱及其伴峰

X光电子能谱(XPS)已成功地应用于过渡元素配合物电子结构的研究.在以往的十多年里,也用XPS研究了稀土元素及其化合物的内壳和价带谱、混合价态谱以及伴峰现象.稀土冠醚配合物的光电子能谱未见文献报道.我们按文献方法叫合成了Ln(NO_3)_23·C_(14)H_(20)O_5(La～Sm),Ln(NO_3)_3·C_(14)H_(20)O_5·3H_2O·(CH_3)_2CO(Eu,Gd)和Ln(NO_3)_3·C_(20)H_(24)O_6(La～     

轻稀土氯化物与2,3,11,12-四苯基-1,4,7,10,13,16-六氧-2,11-十八环二烯配合物的合成及XPS研究

本工作合成了轻稀土氯化物与2,3,11,12-四苯基-1,4,7,10,13,16-六氧-2,11-十八环二烯不饱和冠醚所形成的三种新的轻稀土配合物, 我们着重对这些配合物进行了X射线光电子能谱研究, 得到了组成原子芯能级电子(Ln3d5/2, O 1s, C 1s, Cl 2p)的结合能变化信息。     

Molecular architectures for trimetallic d/f/d complexes: magnetic studies of a LnCu2 core

Five new trinuclear Cu-Ln-Cu cluster complexes have been prepared by a one-pot reaction using H3bcn (tris- N,N',N'-(2-hydroxybenzyl)-1,4,7-triazacyclononane) and Ln = La(III), Nd(III), Gd(III), Dy(III), and Yb(III) where the d- and f-block metal ions are in close proximity desirable for magnetic studies. The [LnCu2(bcn)2]ClO4.nH2O complexes possess the same stoichiometry as the previously reported [LnNi2(bcn)2]ClO4.nH2O and [LnZn2(bcn)2]ClO4.nH2O systems. Additionally, the solid state structures of the LnCu2 complexes appear to be isostructural to the LnNi2 and LnZn2 species as determined by their nearly superimposable IR spectra. The similarities in the structures of the [LnTM2(bcn)2]ClO4.nH2O series, where TM = Zn(II), Ni(II), and Cu(II), allow for direct comparison of their magnetic exchange. An empirical approach, removing first-order anisotropic contributions determined from the analogous [LnZn2(bcn)2]ClO4.nH2O was used to study the d/f/d spin interactions in the [LnCu2(bcn)2]ClO4.nH2O complexes. A ferromagnetic exchange was determined where Ln = Gd(III), Dy(III), or Yb(III) and an antiferromagnetic exchange for Ln = Nd(III), identical to the magnetic exchange observed for the [LnNi2(bcn)2]ClO4.nH2O complexes. An exchange integral of 3.67 cm(-1) for the trimetallic [GdCu2(bcn)2]ClO4.3H2O species was determined using a modified spin Hamiltonian. The [Cu(Hbcn)] and the [Cu3(Hbcn)2](ClO4)2 building blocks of the larger coaggregated d/f/d species were also synthesized, and their structures are reported.     

卤化亚铜三苯基膦络合物的XPS振起伴峰及其价带谱研究

卤化亚铜三苯基膦络合物(Ph_3P)_3Cu_nX_n(n=1,2;X=Cl,Br,I和CN)具有较好的催化活性和选择性,因而引起了人们的注意。X射线衍射研究表明(Ph_3P)_3CuX中Cu具有四配位的结构,而(Ph_3P)_3Cu_2X_2中Cu却具有四配位和三配位的结构。由XPS来表征它们的成键特征的工作尚未见诸报道。实验按文献[6]所述方法制备络合物。经熔点测定、元素分析,证实所制样品的纯度符合要求。按标准方法纯化氯化亚铜和溴化亚铜,并将新制样品置于充满高纯氮的干燥器中。测试     

稀土酞菁配合物的XPS研究

本文合成了一系列稀土单酞菁配合物Lnpc(0AC)2,和Lnpccl(Ln=Tb,Ho, Tm, Lu,Pc为酞菁根, OAC为乙酸根)并用XPS较详细地研究了它们的电子结构, 讨论了它们的化学键性质和组成。     

Sr14-xCaxCu24O41的芯能级光电子发射谱

The core-level X-ray photoelectron emission spectra of the quasi-one dimensional spin 1/2 antiferromagnetic system Sr14-xCaxCu24O41(x=0, 3.5, 6, 7, 8.4) were measured. The main peak of Cu2p3/2 was about 933.8 eV, and the full width of half maximum height was about 3.3 eV. Simulation of Cu2p3/2 by XPSPEAK41 shows that the percents of Cu2+ and Cu3+ in Sr14Cu24O41 are 92.13% and 7.87%, no obvious change to Cu2p core-level is observed by the partial substituting Ca for Sr, and the average valence of Cu in this system is estimated to be 2.08. The main peak of O1s is about 531.0 eV, and the weak shoulder toward the low binding energy direction can be considered as the contribution of Ca-O bond. The binding energies of Ca2p3/2 and Sr3d5/2 indicate that their valence in this system are both +2, without mixed valence.     

Three new Cu(Ⅱ)-Ln(Ⅲ) heterometallic coordination polymers constructed from quinolinic acid and nicotinic acid: Synthesis, structures, and magnetic properties

Three new Cu(Ⅱ)-Ln(Ⅲ) heterometallic coordination polymers based on two N-heterocyclic carboxylic ligands, {[LnCu(L1)2(L2)(H2O)2]·mH2O}n (Ln = La(1), Nd(2), Gd(3), m = 2 (for 1), 1 (for 2, 3), H2L1 = quinolinic acid, HL2 = nicotinic acid), have been synthesized and characterized. 1 has a two-dimensional (2D) layer structure with a Schlfli symbol of (44.62), while complexes 2 and 3 are isostructural and have three-dimensional (3D) structures with a Schlfli symbol of (3.4.5)2(32.42.52.614.74.83.9)(32.63.7) of 3-nodal net. Magnetic investigations suggest that antiferromagnetic coupling exists between NdIII and CuII in 2, while weak ferromagnetic coupling between GdIII and CuII in 3. The difference of magnetic properties between 2 and 3 has been discussed.     

Comparative Studies on Structure and Electronic Properties Between Thermal Lithiated Li_(0.5)MnO_2 and LiMn_2O_4

Monoclinic Li0.5MnO2 was synthesized by solid state reaction and the spectral and magnetic properties were studied in comparison with those of spinel LiMn2O4.The XRD pattern and Raman spectrum of Li0.5MnO2 are different from those of LiMn2O4,which indicate the different long-range and short-range crystal structure.XPS result shows the binding energies of 2p3/2 and 2p1/2 in Li0.5MnO2 are located at 642.3 and 653.6 eV,respectively.Through fitting the XPS spectra,the valence state of Mn ion in Li0.5MnO2 coincides with that in LiMn2O4.The high-temperature susceptibility of Li0.5MnO2 can be fitted by Curie-Weiss law whose Curie and Weiss constants are 33 A·m2·K/(mol·T) and-277(6) K,respectively.Although Li0.5MnO2 shows spin glass ground state,the transition temperature of Li0.5MnO2 is about 9 K lower than that of LiMn2O4.     

Novel 3D LnIII-CuI supramolecular architecture based on 2D MOFs with (6,3) topology

Three novel coordination polymers, [LnCu(PZDC)3].[Ln(H2O)9]0.5.[(H2O)7H+]0.5 [Ln = La (1), Eu (2), Gd (3)], were synthesized. They are the first 3d-4f heterometallic framework with supramolecular 1D channels, in which lanthanide hydrate cations and lattice water molecules are located.     

A series of 3d-4f heterometallic frameworks comprising 2D lanthanide-organic layers and diverse Cu-complex pillars

Six novel 3D layer-pillared lanthanide-transition metal coordination polymers,LnCuX(IN)2(Ac)(H2O)(Ln = Tb,X = Br(1);Ln = Er,X = Cl(2)),[LnCuCl(IN)2(Ac)].H2O(Ln = Gd(3);Ln = Eu(4)),and [LnCu2Br2(IN)2(Ac)(H2O)].nH2O(Ln = Dy,n =0(5);Ln = Gd,n = 0.5(6))(IN = isonicotinate,Ac = acetate),have been obtained by linking Ln-organic layers and diverse Cu-complex pillars under hydrothermal conditions.1 and 2 are isostructural and formed by 2D Ln-IN-Ac layers and CuX(IN)2 pillars(X = Br(1),X= Cl(2));3 and 4 are isomorph...     

Determination of the interface band alignment of Mg2Si/4H-SiC heterojuction for potential photodetector application

The Mg₂Si/4H-SiC heterojunction was prepared by radio frequency (RF) magnetron sputtering technique. The binding energies of Mg 2p, Si 2p, and C 1s core levels and the maxima of valence band were measured by X-ray photoelectron spectroscopy (XPS). Using the optical bandgap of Mg₂Si (0.78 eV) and 4H-SiC (3.25 eV), the band offsets of valence band (VBO) and conduction band (CBO) at Mg₂Si/4H-SiC interface were identified as 1.47 and 1.00 eV, respectively. The band alignment was evaluated to be type-I band alignment. The Mg₂Si/4H-SiC heterojunction could be a promising candidate for the infrared (IR) photodetector.