Growth Mode at the Ge/(1102) Sapphire Interface

1989 ◽  
Vol 159 ◽  
Author(s):  
Geoffrey P. Malafsky

ABSTRACTThe growth mode of Ge on the (1102) surface of sapphire is explored with X-ray photoelectron spectroscopy. Ge exists in two bonding states at the interface, Ge-Ge and Ge-sapphire. Ge forms islands at submonolayer coverage for deposition temperatures of 25°C and 625°C. The formation of the islands is revealed by the rapid increase in the relative fraction of the Ge-Ge bonding state for Ge coverage less than 1 ML. The shift in the Ge-Ge peak binding energy to the bulk Ge value at less than i ML suggests that the islands are three dimensional for deposition at 625°C.

2016 ◽  
Vol 18 (36) ◽  
pp. 25143-25150 ◽  
Author(s):  
F. Rietzler ◽  
B. May ◽  
H.-P. Steinrück ◽  
F. Maier

In vacuo deposition of ultrathin ionic liquid films combined with angle-resolved X-ray photoelectron spectroscopy demonstrates that the initial three-dimensional growth mode of [C2C1Im][OTf] deposited onto the bare Au(111) surface can be switched to two-dimensional growth by adding submonolayer amounts of Pd.


2008 ◽  
Vol 73 (10) ◽  
pp. 1314-1326
Author(s):  
Ivan Jirka ◽  
Zdeněk Bastl

Evolution of niobium-palladium (Nb-Pd) interface alloy prepared by in situ Nb deposition on highly defect polycrystalline Pd surface at room temperature has been investigated using X-ray photoelectron spectroscopy. The binding energies of the Nb 3d5/2 and Pd 3d5/2 core-level lines and their line shapes and the kinetic energies and shapes of Pd M4,5N4,5N4,5 Auger spectrum have been used to characterize the Nb-Pd system. A two-step growth mode of the Nb adlayer has been observed: a two-dimensional (2D)-like growth in a submonolayer Nb concentration region and three-dimensional (3D) intermixing of Nb and Pd atoms at Nb loadings above the monolayer coverage. The latter growth mode resulted in appearance of rather homogeneous Nb-Pd alloy phase.


2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yan Ye ◽  
Da Yin ◽  
Bin Wang ◽  
Qingwen Zhang

We report the synthesis of three-dimensional Fe3O4/graphene aerogels (GAs) and their application for the removal of arsenic (As) ions from water. The morphology and properties of Fe3O4/GAs have been characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and superconducting quantum inference device. The 3D nanostructure shows that iron oxide nanoparticles are decorated on graphene with an interconnected network structure. It is found that Fe3O4/GAs own a capacity of As(V) ions adsorption up to 40.048 mg/g due to their remarkable 3D structure and existence of magnetic Fe3O4nanoparticles for separation. The adsorption isotherm matches well with the Langmuir model and kinetic analysis suggests that the adsorption process is pseudo-second-ordered. In addition to the excellent adsorption capability, Fe3O4/GAs can be easily and effectively separated from water, indicating potential applications in water treatment.


1989 ◽  
Vol 159 ◽  
Author(s):  
E.D. Richmond

ABSTRACTFor the first time the (1102) surface of sapphire has been investigated by X-ray photoelectron spectroscopy to ascertain chemical changes resulting from annealing in vacuum at 1300° C and 1450° C. As received substrates had a substantial surface C contaminant. For substrates that were chemically cleaned before inserting them into the MBE system no trace of carbon is detected. A residual flourine contaminant results from the cleaning procedure and is desorbed by the vacuum annealing. Spectra of annealed substrates are compared to the unannealed chemically cleaned substrates. The annealed substrates exhibit 0.4 to 0.5 eV shift to higher binding energy of the Al peak and a 0.3 eV shift to higher binding energy of the O peak. In addition, a 2% depletion of oxygen from the surface occurs.


MRS Advances ◽  
2016 ◽  
Vol 1 (6) ◽  
pp. 433-439 ◽  
Author(s):  
Asghar Ali ◽  
Patrick Morrow ◽  
Redhouane Henda ◽  
Ragnar Fagerberg

AbstractThis study reports on the preparation of cobalt doped zinc oxide (Co:ZnO) films via pulsed electron beam ablation (PEBA) from a single target containing 20 w% Co on sapphire (0001) and silicon (100) substrates. The films have been deposited at various temperatures (350оC, 400оC, 450оC) and pulse frequencies (2 Hz, 4 Hz), under a background argon (Ar) pressure of about 3 mtorr, and an accelerating voltage of 14 kV. The surface morphology has been examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). According to SEM analysis, the films consist of nano-globules whose size is in the range of 80-178 nm. Energy dispersive x-ray spectroscopy (EDX) reveals that deposition is congruent and the prepared films contain ∼20±5 w% cobalt. It has been found that the nano-globules in the deposited films are cobalt-rich zones containing ∼70 w% Co. From x-ray photoelectron spectroscopy (XPS) analysis, Co 2p3/2 peaks indicate that the deposited films contain CoO (binding energy = 780.5 eV) as well as metallic Co (binding energy = 778.1-778.5 eV). X-ray diffraction (XRD) analysis supports the presence of metallic Co hcp phase (2ϴ = 44.47° and 47.43°) in the films.


2019 ◽  
Vol 21 (18) ◽  
pp. 9399-9406 ◽  
Author(s):  
Marc Figueras ◽  
Carmen Sousa ◽  
Francesc Illas

The influence of electron correlation into the decomposition of core level binding energy shifts, measured by X-ray photoelectron spectroscopy (XPS), into initial and final effects is analysed for a series of molecules where these effects are noticeable.


Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3315 ◽  
Author(s):  
Hao Cheng ◽  
Zhengyuan Zhou ◽  
Yanqing Li ◽  
Wenyi Huang ◽  
Jun Feng ◽  
...  

The detection of difenidol hydrochloride, which is a drug that is widely used for treating the nausea and vomiting symptoms caused by certain diseases, has been increasingly involved in cases of suicide via overdosing and of drug poisoning in children. A novel electrochemiluminescence (ECL) sensor for the simple and effective detection of difenidol hydrochloride was fabricated by modifying a glassy carbon electrode with three-dimensional carbon nanofibers (3D-CNFs). The 3D-CNFs were synthesized by electrospinning a mixture of montmorillonite (MMT) and polyacrylonitrile, carbonizing the electrospun product, and etching it with hydrofluoric acid. The form and structure of the 3D-CNFs was analyzed via scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman microspectroscopy. According to the experimental results obtained using the modified electrodes, a good linear relationship was found between peak intensity and difenidol concentration (y = 868.14x − 61.04, R2 = 0.999), with a relatively low detection limit (8.64 × 10−10 mol·L−1 (S/N = 3)). In addition, our approach exhibited good recovery values ranging from 98.99% to 102.28%. The proposed novel ECL sensor has wide application prospects for the detection of difenidol hydrochloride.


2019 ◽  
Vol 75 (8) ◽  
pp. 1053-1059 ◽  
Author(s):  
Lin-Lu Qian ◽  
Zhi-Xiang Wang ◽  
Hai-Xin Tian ◽  
Min Li ◽  
Bao-Long Li ◽  
...  

Metal–organic frameworks (MOFs) have attracted much interest in the fields of gas separation and storage, catalysis synthesis, nonlinear optics, sensors, luminescence, magnetism, photocatalysis gradation and crystal engineering because of their diverse properties and intriguing topologies. A Cu–MOF, namely poly[[(μ2-succinato-κ2 O:O′){μ2-tris[4-(1,2,4-triazol-1-yl)phenyl]amine-κ2 N:N′}copper(II)] dihydrate], {[Cu(C4H4O4)(C24H18N10)]·2H2O} n or {[Cu(suc)(ttpa)]·2H2O} n , (I), was synthesized by the hydrothermal method using tris[4-(1,2,4-triazol-1-yl)phenyl]amine (ttpa) and succinate (suc2−), and characterized by IR, powder X-ray diffraction (PXRD), luminescence, optical band gap and valence band X-ray photoelectron spectroscopy (VB XPS). Cu–MOF (I) shows a twofold interpenetrating 4-coordinated three-dimensional CdSO4 topology with point symbol {65·8}. It presents good photocatalytic degradation of methylene blue (MB) and rhodamine B (RhB) under visible-light irradiation. A photocatalytic mechanism was proposed and confirmed.


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