Molecular structure characterization of middle-high rank coal via^(13)C NMR,XPS,and FTIR spectroscopy

Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.

XPS Studies of Magnetic Multilayers

NiOx/Ni81Fe19 and Co/AlOx/Co magnetic multilayers were fabricated by reactive RF/DC magnetron sputtering on clean glass substrates and oxidized Si (100) substrates, respectively. The exchange biasing field (H-ex) between NiO4 and Ni81Fe19 as a function of NiOx oxidation states was studied by X-ray photoelectron spectroscopy (XPS). The oxidation states and the oxide thickness of Al layers in magnetic multilayer films consisting of Co/AlOx/Co were also analyzed. It is found that the H-sr of NiOx/Ni81Fe19 films only depends on Ni2+ but not on Ni3+ or Ni. The bottom Co can be completely covered by depositing an A I layer thicker than 2.0 nm. The oxide layer was Al2O3, and its thickness was 1.15 mn.

XPS Studies of Chemical States of NiO/NiFe Interface

Ta/NTiO/NiFe/Ta multilayers were prepared by radio frequency reactive and dc magnetron sputtering. The exchange coupling field between NiO and NiFe reached 9.6 x 10(3) A/m. The compositions and chemical states at the interface region of NiO/NiFe were studied using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique, The results show that there are two thermodynamically favorable reactions at NiO/NiFe interface: NiO+Fe = Ni + FeO and 3NiO+2Fe =3 Ni+Fe2O3. The thickness of the chemical reaction area estimated by angle-resolved XPS was about 1-1.5 nm. These interface reaction products appear magnetic defects, and the exchange coupling field H-ex and the coereivity H-c of NiO/NiFe are affected by these defects.

Photoelectric characteristics of silicon P–N junction with nanopillar texture:Analysis of X-ray photoelectron spectroscopy

Silicon nanopillars are fabricated by inductively coupled plasma （ICP） dry etching with the cesium chloride （CsCl） islands as masks originally from self-assembly. Wafers with nanopillar texture or planar surface are subjected to phosphorus （P） diffusion by liquid dopant source （POCl3） at 870 ℃ to form P-N junctions with a depth of 300 nm. The X-ray photoelectron spectroscopy （XPS） is used to measure the Si 2p core levels of P-N junction wafer with nanopillar texture and planar surface. With a visible light excitation, the P-N junction produces a new electric potential for photoelectric characteristic, which causes the Si 2p core level to have a energy shift compared with the spectrum without the visible light. The energy shift of the Si 2p core level is -0.27 eV for the planar P-N junction and -0.18 eV for the nanopillar one. The difference in Si 2p energy shift is due to more space lattice defects and chemical bond breaks for nanopillar compared with the planar one.

Landscape of s-triazine molecule on Si(100) by a theoretical x-ray photoelectron spectroscopy and x-ray absorption near-edge structure spectra study

The chemisorbed structure for an aromatic molecule on a silicon surface plays an important part in promoting the development of organic semiconductor material science. The carbon K-shell x-ray photoelectron spectroscopy（XPS） and the x-ray absorption near-edge structure（XANES） spectra of the interfacial structure of an s-triazine molecule adsorbed on Si（100） surface have been performed by the first principles, and the landscape of the s-triazine molecule on Si（100） surface has been described in detail. Both the XPS and XANES spectra have shown their dependence on different structures for the pristine s-triazine molecule and its several possible adsorbed configurations. By comparison with the XPS spectra, the XANES spectra display the strongest structural dependency of all of the studied systems and thus could be well applied to identify the chemisorbed s-triazine derivatives. The exploration of spectral components originated from non-equivalent carbons in disparate local environments has also been implemented for both the XPS and XANES spectra of s-triazine adsorbed configurations.

XPS and PAT Study on NiAl Phase Formed in a Superalloy by Pack Cementation

The NiAl phase prepared by pack cementation （PC） on a nickel base superalloy was investigated by X-ray photoelectron spectroscopy （XPS） and positron annihilation technique （PAT）. The focus was on the effect of the solid solution of the alloying element from substrate on the binding energy of Ni （Al） 2p peaks and vacancy concentration of the NiAI phase formed in a superalloy. The results showed that the binding energy of Ni 2p peak of the NiAI phase grown in a superalloy was shifted by up to 0.55 eV at the temperature from 850 to 1050℃ towards higher energies and the binding energy of Al 2p peak by up to 1.09 eV in comparison with the NiAl phase formed in pure Ni. The positron lifetimes obtained from the NiAl phase formed in a superalloy were found to be markedly lower than the theoretical values, indicating the decrease in vacancy concentration. The variation of binding energies and vacancy concentration are possibly due to the solid solution of the alloying atoms from the substrate into the NiAI lattice.

Band alignment of p-type oxide/ε-Ga2O3 heterojunctions investigated by x-ray photoelectron spectroscopy

Theε-Ga2O3 p-n heterojunctions(HJ)have been demonstrated using typical p-type oxide semiconductors(NiO or SnO).Theε-Ga2O3 thin film was heteroepitaxial grown by metal organic chemical vapor deposition(MOCVD)with three-step growth method.The polycrystalline SnO and NiO thin films were deposited on theε-Ga2O3 thin film by electron-beam evaporation and thermal oxidation,respectively.The valence band offsets(VBO)were determined by x-ray photoelectron spectroscopy(XPS)to be 2.17 eV at SnO/ε-Ga2O3 and 1.7 eV at NiO/ε-Ga2O3.Considering the bandgaps determined by ultraviolet-visible spectroscopy,the conduction band offsets(CBO)of 0.11 eV at SnO/ε-Ga2O3 and 0.44 eV at NiO/ε-Ga2O3 were obtained.The type-Ⅱband diagrams have been drawn for both p-n HJs.The results are useful to understand the electronic structures at theε-Ga2O3 p-n HJ interface,and design optoelectronic devices based onε-Ga2O3 with novel functionality and improved performance.

MAXIMUM ENTROPY DECONVOLUTION OF XPS PEAK

Necessity of XPS spectrum deconvolution, disadvantages of the traditional Fast Fourier Transform decon-volution method (FFT) , principle, method and advantages of Maximum Entropy Deconvolution Method (MEM) are de-scribed. Criteria for determing the number of data points sam-pled in MEM are the main point disccussed in the paper,some XPS deconvolution applications of our MEM software show that the MEM makes XPS deconvolution much easier than the traditional FFT method.

Theoretical characterization of the adsorption configuration of pyrrole on Si(100)surface by x-ray spectroscopy

The possible configurations of pyrrole absorbed on a Si(100)surface have been investigated by x-ray photoelectron spectroscopy(XPS)and near-edge x-ray absorption fine structure(NEXAFS)spectra.The C-1s XPS and NEXAFS spectra of these adsorption configurations have been calculated by using the density functional theory(DFT)method and fullcore hole(FCH)approximation to investigate the relationship between the adsorption configurations and the spectra.The result shows that the XPS and NEXAFS spectra are structurally dependent on the configurations of pyrrole absorbed on the Si(100)surface.Compared with the XPS,the NEXAFS spectra are relatively sensitive to the adsorption configurations and can accurately identify them.The NEXAFS decomposition spectra produced by non-equivalent carbon atoms have also been calculated and show that the spectral features vary with the diverse types of carbon atoms and their structural environments.

X射线光电子能谱技术及其应用

X射线光电子能谱法(XPS)是最重要且使用最广泛的表面分析技术。较为全面地介绍了X射线能谱法,内容涵盖原理、分析方法、应用及技术进展。原理介绍基于理工科大学本科层级的知识,阐述了XPS的科学原理以及仪器原理;分析方法部分概述了分析的关键步骤及要点;应用部分以热门研究的材料类型分类(催化剂、生物材料、碳材料、高分子材料等)进行介绍,介绍的同时兼顾介绍了X射线光电子能谱法的一些常用技术以及在各种材料中的应用特点。本文旨在帮助该领域的初学者,包括尚未完全熟悉该技术的研究人员、研究生和X射线光电子能谱从业人员,使他们能够全面了解X射线光电子能谱技术。

大米中营养元素分布及与加工精度的关系

以水稻龙粳40作为研究对象,依据GB/T 5502—2008《粮油检验:米类加工精度检验》染色法,加工得到不同等级大米,运用电感耦合等离子体质谱仪测定不同等级大米中17种营养元素的含量,并通过X射线光电子能谱仪对水稻籽粒颖果外表面、近表面、近中部和米中部的元素含量进行定量分析。结果表明,不同加工等级间大米中Na、Mg、K、Ca、Cr、Mn、Co、Cu、Zn、Rb和Sr的11种元素存在极显著差异(P<0.01),并且11种元素在不同等级间损失率不同;Na、K、Ca、Fe元素在水稻籽粒不同部位的含量有差异,颖果表面Na、K、Ca、Fe含量较高,近中部和米中部含量较低。各营养元素在稻谷中分布不均匀,在加工过程中,营养元素将不同程度地损失。

钨掺杂α-FeOOH制备及染料废水降解

针对现今水污染问题,采用空气氧化法在碱性条件下制备了α-Fe OOH和钨掺杂α-Fe OOH来降解污水中的染料.利用傅里叶红外光谱仪、扫描电子显微镜、X射线衍射仪和光电子能谱仪等对样品的形貌和结构进行了表征.以α-Fe OOH作为Fenton反应的铁源并与过氧化氢形成Fenton体系,考察该体系对染料甲基橙和酸性铬兰k溶液的降解性能.结果表明,在最佳条件下,当加入钨掺杂α-Fe OOH时,甲基橙和酸性铬兰k的降解率分别达到99.8%和81.0%;同样条件下,当加入无掺杂α-Fe OOH时,甲基橙和酸性铬兰k的降解率只有75.2%和61.3%.

季铵铜防腐剂对马尾松木材化学性质的影响

为了研究季铵铜(ACQ)防腐剂对木材化学性质的影响,以马尾松木材为研究对象,运用pH计、酸碱滴定管、X射线光电子能谱仪、傅立叶变换红外光谱仪对ACQ处理前后木材的pH值、缓冲容量、表面化学元素和官能团变化进行了分析。与未处理材相比,经ACQ(浓度为1.0%)处理后的马尾松木材pH值、酸/碱缓冲容量明显增大;随着ACQ浓度由0.1%升高至1.0%,处理材的pH值以及酸/碱缓冲容量呈增加趋势,缓冲容量曲线趋为平缓。ACQ防腐处理引起了木材化学元素组成和官能团强度的变化,具体表现为Cu含量及O/C元素比增加,C1/C元素比减小,木质素红外吸收峰(1509、1267 cm-1)和半纤维素红外吸收峰(1732 cm-1)强度减弱,表明ACQ组分主要与马尾松木材中的木质素和半纤维素发生结合。

Characterization of Pyrolytic Lignin Extracted from Bio-oil

Bio-oil is a new liquid fuel produced by fast pyrolysis,which is a promising technology to convert bio-mass into liquid. Pyrolytic lignin extracted from bio-oil,a fine powder,contributes to the instability of bio-oil. The paper presents the structural features of three kinds of pyrolytic lignin extracted from bio-oil with different methods(WIF,HMM,and LMM) . The pyrolytic lignin samples are characterized by Fourier transform infrared spectrometer(FTIR) and X-ray photoelectron spectroscopy(XPS) . FTIR data indicate that the three pyrolytic lignin samples have similar functional groups,while the absorption intensity is different,and show characteristic vibra-tions of typical lignocellulosic material groups O H(3340-3380 cm-1) ,C H(2912-2929 cm-1) and C O(1652-1725 cm-1) . Comparison in the region(3340-3380 cm-1) indicates that WIF has more O H stretch groups than HMM and LMM. The carbon spectra are fitted to four peaks:C1,C C or C H,BE 283.5 eV;C2,C OR or C OH,BE 284.5-285.8 eV;C3,C O or HO C OR,BE 286.10-287.10 eV;C4,O C O,BE 287.5-287.7 eV. The absence of C1,C C or C H indicates the dominant polymerization structure of aro-matic carbon in pyrolytic lignin samples. For HMM and WIF,C2a and C2b can not be separated,so there is no free hydroxyl group in the samples. The oxygen peaks are also fitted to four peaks:O1,OH,BE = 530.3 eV;O2,RC O,BE 531.45-531.72 eV;O3,O C O,BE = 532.73-533.74 eV;O4,H2O,BE 535 eV. The absence of O1 and O4 indicates that little hydroxyl groups and adsorbed water are present in the samples.

Annealing temperature dependent catalytic water oxidation activity of iron oxyhydroxide thin films

Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）, field emission scanning electron microscopy（FE-SEM） and linear sweep voltammetry（LSV） to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe;O;with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction（OER） in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm;and shows good stability in the 1 M KOH electrolyte solution.

EFFECT OF CERIUM ION IMPLANTATION ON THE AQUEOUS CORROSION BEHAVIOR OF ZIRCONIUM

In order to study the influence of cerium ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted by cerium ions with a dosage range from 1×1016 to 1×1017 ions/cm2 at about 150℃, using MEVVA source at an acceler ative voltage of 40kV. The valence of the surface layer was analyzed by X-ray photo- electron spectroscopy (XPS); Three-sweep potentiodynamic polarization measurement was employed to value the aqueous corrosion resistance of zirconium in a 0.5mol/L H2SO4 solution. It was found that a remarkable decline in the aqueous corrosion behavior of zirconium implanted with cerium ions compared with that of the as-received zirconium. Finally, the mechanism of the corrosion resistance decline of the cerium-implanted zirconium is discussed.

Surface State of Carbon Fibers Modified by Electrochemical Oxidation

Surface of polyacrylonitrile (PAN)-based carbon fibers was modified by electrochemical oxidation. The modification effect on carbon fibers surface was explored using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Results showed that on the modified surface of carbon fibers, the carbon contents decreased by 9.7% and the oxygen and nitrogen contents increased by 53.8% and 7.5 times, respectively. The surface roughness and the hydroxyl and carbonyl contents also increased. The surface orientation index was reduced by 1.5% which decreased tensile strength of carbon fibers by 8.1%, and the microcrystalline dimension also decreased which increased the active sites of carbon fiber surface by 78%. The physical and chemical properties of carbon fibers surface were modified through the electrochemical oxidative method, which improved the cohesiveness between the fibers and resin matrix and increased the interlaminar shear strength (ILSS) of carbon fibers reinforced epoxy composite (CFRP) over 20%.

Effect of Mo on microstructure,mechanical and corrosion properties of FeCrNiMnMox high-entropy alloys

Four FeCrNiMnMo_(x)(x=0,0.1,0.3,0.5,in molar ratio)high-entropy alloys(HEAs)were synthesized by vacuum arc melting to explore the potential impact of Mo on the microstructure,mechanical properties,and passivation and electrochemical behaviors in 0.5 M H_(2)SO_(4)solution.The results display that the FeCrNiMn alloy exhibits a single face-centered cubic(FCC)structure while the microstructures of the FeCrNiMnMo_(0.1),FeCrNiMnMo_(0.3),and FeCrNiMnMo_(0.5)alloys consist of the FCC andσphase.The appear of theσphase ascribed to the addition of Mo enhances the hardness and yield strength with the sacrifice of plasticity.The FeCrNiMnMox HEAs achieve the maximum hardness of 414 HV_(0.2)and the highest compressive yield strength of 830 MPa when x=0.5,but compressive fracture strain is lowered to 10.8%.X-ray photoelectron spectroscopy(XPS)and electrochemical analysis show that the passivation film in FeCrNiMnMox alloy mainly consists of chromium oxides and molybdenum oxides.Mo has a beneficial effect on the corrosion resistance of the FeCrNiMnMox HEAs in a 0.5 M H_(2)SO_(4)solution by increasing the corrosion potential(E_(corr))and decreasing the corrosion current density(I_(corr))and passivation current density(I_(pass)).The FeCrNiMnMo_(0.1)alloy shows the best corrosion resistance,mainly due to its passivation film consisting of a large proportion of chromium oxide(Cr_(2)O_(3)).More Mo additions promote the formation of the precipitate ofσphase and the matrix regions depleted Cr and Mo elements adverse to the resistance to preferential localized corrosion.

A nano-scale mirror-like surface of Ti–6Al–4V attained by chemical mechanical polishing

Metal Ti and its alloys have been widely utilized in the fields of aviation, medical science, and micro-electromechanical systems, for its excellent specific strength, resistance to corrosion, and biological compatibility. As the application of Ti moves to the micro or nano scale, however, traditional methods of planarization have shown their short slabs.Thus, we introduce the method of chemical mechanical polishing（CMP） to provide a new way for the nano-scale planarization method of Ti alloys. We obtain a mirror-like surface, whose flatness is of nano-scale, via the CMP method. We test the basic mechanical behavior of Ti–6Al–4V（Ti64） in the CMP process, and optimize the composition of CMP slurry.Furthermore, the possible reactions that may take place in the CMP process have been studied by electrochemical methods combined with x-ray photoelectron spectroscopy（XPS）. An equivalent circuit has been built to interpret the dynamic of oxidation. Finally, a model has been established to explain the synergy of chemical and mechanical effects in the CMP of Ti–6Al–4V.

INFLUENCE OF THE NONMAGNETIC METAL SPACER ON THE MAGNETIC PROPERTIES AND MICROSTRUCTURE OF THE MULTILAYER FILMS

Ta / NiFe/Bi （ Ag, Cu ）/FeMn/Ta and Ta / NiFe1/FeMn / Bi （ Ag, Cu ）/NiFen/Ta films were prepared by magnetic sputtering. The texture and the dependences of the exchange-coupling field on the thickness of Bi, Ag, and Cu in Ta/NiFe/Bi（Ag, Cu） /FeMn/Ta and Ta/NiFe/FeMn/Bi（Ag, Cu）/NiFe/Ta films were studied. XPS results indicate that the Bi atoms migrated into the FeMn layer during the deposition process and a FeMnBi alloy was probably formed or the Bi atoms existed as an impurity in the FeMn layer in Ta/NiFe/Bi（Ag, Cu ）/FeMn/Ta. Otherwise, in Ta/NiFe/FeMn/Bi （Ag, Cu）/NiFe/Ta films, Bi, Ag, and Cu atoms do not remain entirely at the interface of the FeMn/ NiFeⅡfilm, but at least partly segregate to the surface of the NiFe film.