Electron Spectroscopic Studies of Substoichiometric Tantalum Carbide

1985 ◽  
Vol 48 ◽  
Author(s):  
G. R. Gruzalski ◽  
D. M. Zehner ◽  
G. W. Ownby
Keyword(s):  
Charge Transfer ◽  
Binding Energy ◽  
Fermi Level ◽  
Valence Band ◽  
Spectroscopic Studies ◽  
Tantalum Carbide ◽  
Binding Energies ◽  
Defect States ◽  
Valence Band Structure ◽  
Band Spectra

ABSTRACTXPS was used to determine core-level binding energies and valence-band structure for TaCx over the range 0.5 ≲ × ≲ 1.0. As x decreased, the carbonls binding energy (BE) changed very little, the carbon-2s BE shifted toward the Fermi level, the position of the p-d valence-band peak shifted toward the Fermi level more, and the tantalum-4d and -4f BE's shifted toward the Fermi level even more, about 0.16 eV for a change in × of 0.1. In addition, the valence-band spectra exhibited structure between about 1 and 2 eV BE, and this structure increased as x decreased. These observations are explicable in terms of charge transfer and the formation of occupied defect states associated with carbon vacancies.

scholarly journals The investigation of 2D monolayers as potential chelation agents in Alzheimer’s disease

2019 ◽  
Author(s):  
Neha Pavuluru ◽  
Xuan Luo
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Charge Transfer ◽  
Binding Energy ◽  
Amyloid Beta ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Binding Energies ◽  
Amyloid Beta Protein ◽  
Functional Theory

In this study, we conducted Density Functional Theory calculations comparing the binding energy of the copper- Amyloid-beta complex to the binding energies of potential chelation materials. We used the first-coordination sphere of the truncated high-pH Amyloid-beta protein subject to computational limits. Binding energy and charge transfer calculations were evaluated for copper’s interaction with potential chelators: monolayer boron nitride, monolayer molybdenum disulfide, and monolayer silicene. Silicene produced the highest binding energies to copper, and the evidence of charge transfer between copper and the monolayer proves that there is a strong ionic bond present. Although our three monolayers did not directly present chelation potential, the absolute differences between the binding energies of the silicene binding sites and the Amyloid-beta binding site were minimal proving that further research in silicene chelators may be useful for therapy in Alzheimer’s disease.

PHOTOELECTRON SPECTROSCOPIC STUDY OF κ-(BEDT-TTF)2Cu(NCS)2 ORGANIC SUPERCONDUCTOR

1992 ◽  
Vol 06 (28) ◽  
pp. 1785-1791 ◽  
Author(s):  
R. ITTI ◽  
H. MORI ◽  
K. IKEDA ◽  
I. HIRABAYASHI ◽  
N. KOSHIZUKA ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Band Structure ◽  
Valence Band ◽  
Binding Energies ◽  
Organic Superconductor ◽  
Two Dimensional ◽  
Valence Band Structure ◽  
X Ray ◽  
Dimensional Network ◽  
Valence Band Region

Experimental evidence for understanding the transport and electrical properties of the 10.4 K organic superconductor κ-(BEDT-TTF)2Cu(NCS)2 (where BEDT-TTF represents bis(ethylenedithio)tetrathiafulvalene) has been achieved by X-ray and ultraviolet photoelectron spectroscopic (XPS and UPS) measurements. Chemical environment of the atoms in this organic superconductor is discussed based on the XPS core-level results. Binding energies of the inequivalent C and S sites in the cation BEDT-TTF and the anion Cu(NCS)2 are found to be different and an assignment is made. The valences of Cu and N were observed to be typically +1 and −3, respectively. The results indicate that bonding is somewhat covalent in the BEDT-TTF while it is ionic in the Cu(NCS)2, i.e., conduction in this compound occurs essentially on the two-dimensional network of the BEDT-TTF molecules. Measurements of the valence band region revealed a broad valence band structure with several peak features.

Characterization of Fluorinated Multi-Walled and Single-Walled Carbon Nanotubes Using High Resolution XPS and EDX

2013 ◽  
Vol 699 ◽  
pp. 194-199
Author(s):  
Ling Zhi Sun ◽  
Xu Zhang
Keyword(s):  
Carbon Nanotubes ◽  
High Resolution ◽  
Binding Energy ◽  
Valence Band ◽  
Single Walled Carbon Nanotubes ◽  
X Ray ◽  
Single Walled Carbon ◽  
Multi Walled Carbon Nanotubes ◽  
Band Spectra ◽  
Walled Carbon Nanotubes

Pristine and fluorinated multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) were characterized using energy dispersive X-ray spectra (EDX) and X-ray photoelectron spectroscopy (XPS), respectively. The fluorine percentages of fluorinated multi-walled carbon nanotubes (F-MWCNTs) and fluorinated single-walled carbon nanotubes (F-SWCNTs) were 10.42% and 9.67% respectively by EDX. The absorption and de-absorption of fluorine properties were studied using high resolution C 1s and F 1s core level XPS and valence band spectra. The fluorine can be completely dissociated from F-MWCNTs, but partially dissociated from SWCNTs. There was 5.79% fluorine in atomic percent remaining associated with the F-SWCNTs when annealing the nanotubes to 500 °C measured by EDX. The results of F 1s core level XPS indicated that the binding energy of fluorine associated on SWCNTs was shifted from 687.0 eV to 688.3 eV after annealing the nanotubes to 500 °C. The results of valence band spectra showed that the binding energy of F 2p and F 2s shifted from 7.5 eV and 31.0 eV to 8.8 eV and 32.5 eV respectively in SWCNTS. However, the two peaks disappeared in annealed MWCNTs.

PHOTOEMISSION STUDY OF PURE AND Cs-INTERCALATED VSe2

1994 ◽  
Vol 08 (20) ◽  
pp. 1261-1268 ◽  
Author(s):  
H.I. STARNBERG ◽  
H.E. BRAUER ◽  
P.O. NILSSON ◽  
L.J. HOLLEBOOM ◽  
H.P. HUGHES
Keyword(s):  
Charge Transfer ◽  
Band Structure ◽  
Valence Band ◽  
Band Model ◽  
Valence Band Structure ◽  
Band Structure Calculations ◽  
Band Dispersion ◽  
Self Consistent ◽  
Photoemission Study ◽  
Structure Calculations

We report photoemission studies of the valence band structure of VSe 2 and of VSe2 intercalated with Cs. Pure VSe 2 showed significant band dispersion both perpendicular and parallel to the layers, i.e. the valence band of VSe 2 is 3D in character, confirming self-consistent LAPW band structure calculations. After Cs intercalation the perpendicular band dispersion vanished, while that parallel to the layers remained, showing that the valence band structure had become 2D. The observed changes go far beyond the rigid band model, but are largely understandable in terms of intercalation-induced decoupling of the VSe 2 layers, and charge transfer from the Cs.

scholarly journals The investigation of 2D monolayers as potential chelation agents in Alzheimer’s disease

2019 ◽  
Author(s):  
Neha Pavuluru ◽  
Xuan Luo
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Charge Transfer ◽  
Binding Energy ◽  
Amyloid Beta ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Binding Energies ◽  
Amyloid Beta Protein ◽  
Functional Theory

In this study, we conducted Density Functional Theory calculations comparing the binding energy of the copper- Amyloid-beta complex to the binding energies of potential chelation materials. We used the first-coordination sphere of the truncated high-pH Amyloid-beta protein subject to computational limits. Binding energy and charge transfer calculations were evaluated for copper’s interaction with potential chelators: monolayer boron nitride, monolayer molybdenum disulfide, and monolayer silicene. Silicene produced the highest binding energies to copper, and the evidence of charge transfer between copper and the monolayer proves that there is a strong ionic bond present. Although our three monolayers did not directly present chelation potential, the absolute differences between the binding energies of the silicene binding sites and the Amyloid-beta binding site were minimal proving that further research in silicene chelators may be useful for therapy in Alzheimer’s disease.

PHOTOINDUCED PHASE TRANSITION OF A SPIN-CROSSOVER COMPLEX STUDIED WITH THE COMBINATION OF SR AND LASER

2002 ◽  
Vol 09 (01) ◽  
pp. 319-323
Author(s):  
KAZUTOSHI TAKAHASHI ◽  
MASAO KAMADA ◽  
YO-ICHIRO DOI ◽  
KAZUTOSHI FUKUI ◽  
TAKESHI TAYAGAKI ◽  
...  
Keyword(s):  
Phase Transition ◽  
Valence Band ◽  
High Spin ◽  
Spin Crossover ◽  
Electron Charge ◽  
Valence Band Structure ◽  
Thermally Induced ◽  
The Core ◽  
Band Spectra ◽  
Photoemission Study

We have performed a photoemission study on an organometal spin-crossover complex, [ Fe(2-pic) 3] Cl 2 EtOH , using the combination of synchrotron radiation and laser. The core-level and valence-band photoemission spectra were measured for high-spin, low-spin, and photoinduced phases. The N 1s and valence-band spectra showed remarkable changes due to the photoinduced phase transition, indicating that the electron charge was transferred from nitrogen to iron at the photoinduced phase transitions. It was also found that the valence-band structure of the photoinduced phase is very different from that of the high-spin phase caused by the thermally induced phase transition.

Valence-band spectra of BEDT-TTF and TTF-based magnetic charge-transfer salts

2002 ◽  
Vol 65 (23) ◽  
Author(s):  
E. Z. Kurmaev ◽  
A. Moewes ◽  
S. G. Chiuzbian ◽  
L. D. Finkelstein ◽  
M. Neumann ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Valence Band ◽  
Magnetic Charge ◽  
Charge Transfer Salts ◽  
Band Spectra

X-Ray Photoelectron Spectroscopic Studies of Carbon Fiber Surfaces. Part XVI: Core-Level and Valence-Band Studies of Pitch-Based Fibers Electrochemically Treated in Ammonium Carbonate Solution

1992 ◽  
Vol 46 (4) ◽  
pp. 645-651 ◽  
Author(s):  
Yaoming Xie ◽  
Tiejun Wang ◽  
Oliver Franklin ◽  
Peter M. A. Sherwood
Keyword(s):  
Carbon Fiber ◽  
Valence Band ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Treatment Time ◽  
Spectroscopic Studies ◽  
Core Level ◽  
Short Treatment ◽  
X Ray ◽  
Band Spectra

DuPont E-120 high-modulus pitch-based carbon fibers were treated electrochemically in 0.5 M (NH4)2CO3 solution under both potentiostatic and galvanostatic modes. X-ray photoelectron spectroscopy (XPS) was used to monitor the chemical changes on the carbon fiber surfaces. Both core-level and valence-band spectra showed that the treatment introduced both oxygen-containing and nitrogen-containing functional groups onto the fiber surfaces, and the mainly oxygen-containing functional groups produced were carbonyl (C=O) type functional groups after longer treatment time. For short treatment time, hydroxide (C-OH) type groups were the dominant functionality, and ether (C-O-C) or epoxide type groups were also formed. The O 2 s peaks from oxygen atoms in the hydroxide functionality and the ether or epoxide groups are well separated in the valence-band spectra; the corresponding O 1 s peaks, however, are not separated in the O 1 s core-region spectra.

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

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