eV Satellite Research Articles

Metal organic framework supported surface modification of synthesized nickel/nickel oxide nanoparticles via controlled PEGylation for cytotoxicity profile against MCF-7 breast cancer cell lines via docking analysis

Metal organic framework, (MOFs) supported nanoparticles have proven a path for the treatment of various carcinomas to be effective against MCF-7 Breast cancer cell lines. Despite the globally widespread applications of nickel/nickel oxide nanoparticles, Ni/NiO@LAA_PEG NPs with surfactant Polyethylene glycol, (PEG) and l-Acsorbic acid, (LAA) as reducing agents in industrial, commercial, and biomedical fields, their response to human cells has not been elucidated. Hence in the reported article Ni/NiO@LAA_PEG NPs with an average size range of 75–80 nm was used to study their interaction with MCF-7 Breast cancer cell lines. So the best of our understanding this is the study related to MCF-7 Human Breast cancer cell lines to show cyto-genotoxicity of Ni/NiO@LAA_PEG NPs which seems mediated through MTT analysis with rising effect surface enhancement and indexed porosiveness for the interfacial advancement than standard drug Doxorubicin for their comparison to show their best effectivity to prepared Ni/NiO@LAA_PEG NPs.The theoretical performance was simulated using Gaussian-09@Autodock 4.2 with crystal preparation and docked with MCF-7 Human Breast cancer cell lines PDBs to show their correlation with wet method of preparation. The synthesized Ni/NiO@LAA_PEG NPs was characterized against UV/Vis spectroscopy for determination of peak pattern of 395 nm, the functional group analysis for the best binding of stretching with framed metal network of nanoparticles was to shown out their scissoring, wagging, and CH stretching, etc. at 661, 834 and 3425 cm−1respectively by FTIR analysis and an energy band gap of 2.2 eV for Ni/NiO@LAA_PEG NPs by optical studies. The mesopore range and surface area measurement was calculated with BET adsorption and BJH plot to find their coercivity and retentivity via adsorption-desorption curve for their best catalytic performance. The current interpretation of Ni 2p spectra of oxides and other compounds is based on charge transfer assignment of the main peak at 856.4 eV and broad satellite cantered at about 861 eV to the cd9 L and unscreened cd8 final state configurations.

Loss for photoemission versus gain for Auger: Direct experimental evidence of crystal-field splitting and charge transfer in photoelectron spectroscopy

Here, we find a 5 eV satellite in the Ti1s photoelectron spectrum of the transition-metal oxide SrTiO3. This satellite appears in addition to the well-studied 13 eV structure that is typically associated with the Ti2p core line. We give direct experimental evidence that the presence of two satellites is due to the crystal-field splitting of the metal 3d orbitals. They originate from ligand 2pt2g → metal3dt2g and ligand 2peg → metal 3deg monopole charge-transfer excitations within the sudden approximation of quantum mechanics. This assignment is made by the energetics of the resonant and high-energy threshold behaviors of the TiK–L2L3 Auger decay that follows Ti1s photoionization.

The influence of Gd/Ce substitution on the magnetic properties, electronic structure and the valence of cerium in the solid solution CexGd1−xNi3

The polycrystalline compounds CexGd1−xNi3 with a rhombohedral PuNi3 (x ≤ 0.2) and hexagonal CeNi3 (x ≥ 0.8) – type of crystal structures have been obtained. The change of the lattice parameters may suggest an unstable valence of cerium in the studied system. The effect of partial substitution of Gd by Ce is reflected in a change of the cell volume V(x), the Curie temperature TC(x) and in the temperature dependence of the magnetic susceptibility and electrical resistivity. Thus, TC(x) decreases from 115 K (x = 0) to ∼6.8 K (x = 0.8). The XPS spectra have been measured at room temperature. The valence band spectra (VB) as well as the core level lines have been analysed as influence of the Gd/Ce substitution on the electronic structure. The VB near the Fermi level (EF) is dominated by Ni3d states. In the VB region some slight effects of hybridization and changes of intensity of states on EF have been noticed. The analysis of Ce core level lines reveals the occurrence of possible intermediate valence. The values of the Ce4f - state occupation parameter (nf) and the hybridization energy (Δ) have been estimated. The gradual filling of the Ni3d band is revealed by a reduction of the 6 eV satellite intensities in the Ni2p core level spectrum. All these effects can modify the magnetic properties of the investigated compounds.

Magnetic Compton profiles of Fe and Ni corrected by dynamical electron correlations

Magnetic Compton profiles (MCPs) of Ni and Fe along the [111] direction have been calculated using a combined density functional and many-body theory approach. At the level of the local spin density approximation, the theoretical MCPs do not describe correctly the experimental results around the zero momentum transfer. In this work, we demonstrate that inclusion of electronic correlations as captured by dynamical mean-field theory (DMFT) improves significantly the agreement between the theoretical and the experimental MCPs. In particular, an energy decomposition of Ni MCPs gives an indication of spin polarization and the intrinsic nature of the Ni 6 eV satellite, a genuine many-body feature.

First-Principles Dynamical Coherent-Potential Approximation Approach to the Ferromagnetism of Fe, Co, and Ni

Magnetic properties of Fe, Co, and Ni at finite temperatures have been investigated on the basis of the first-principles dynamical CPA (Coherent Potential Approximation) combined with the LDA (Local Density Approximation) + $U$ Hamiltonian in the Tight-Binding Linear Muffintin Orbital (TB-LMTO) representation. The Hamiltonian includes the transverse spin fluctuation terms. Numerical calculations have been performed within the harmonic approximation with 4th-order dynamical corrections. Calculated single-particle densities of states in the ferromagnetic state indicate that the dynamical effects reduce the exchange splitting, suppress the band width of the quasi-particle state, and causes incoherent excitations corresponding the 6 eV satellites. Results of the magnetization vs temperature curves, paramagnetic spin susceptibilities, and the amplitudes of local moments are presented. Calculated Curie temperatures ($T_{\rm C}$) are reported to be 1930K for Fe, 2550K for Co, and 620K for Ni; $T_{\rm C}$ for Fe and Co are overestimated by a factor of 1.8, while $T_{\rm C}$ in Ni agrees with the experimental result. Effective Bohr magneton numbers calculated from the inverse susceptibilities are 3.0 $\mu_{\rm B}$ (Fe), 3.0 $\mu_{\rm B}$ (Co), and 1.6 $\mu_{\rm B}$ (Ni), being in agreement with the experimental ones. Overestimate of $T_{\rm C}$ in Fe and Co is attributed to the neglects of the higher-order dynamical effects as well as the magnetic short range order.

The influence of localized excitations on spin-selective electron scattering and auger emission in transition metals

Observed spin asymmetry of polarized electrons backscattered from ferromagnetic metallic glasses and spin polarization of Auger electrons in magnetic transition metals can be explained qualitatively in terms of spin-selective scattering involving intermediate excitation of a transient 3p → 3d localized state. Consideration of photoemission data and of prior theoretical models indicates that this state decays selectively by Auger emission, producing the observed main MVV Auger peak. The final state of this transition is identified with the state whose direct excitation is observed in photoemission for the transition metals as a 6–7 eV satellite.

Evolution of the 2p satellite of Ni nano-clusters onTiO2(001) surfaces

Correlation enhancement of electrons in Ni nano-clusters due to confinementin reduced dimensions has been observed. Both the size and shape of thenano-clusters have a strong influence on the Ni 2p satellite structures. For smallNi clusters, apart from the 6 eV satellite, a 3 eV satellite structure emerges inNi 2p3/2 photoemission spectra due to the existence of the3F atomic state. However, the intensity of the 3 eV satellite decreases with increasing cluster sizebecause the Ni 3d level becomes increasingly occupied in large clusters. The increased electronpopulation in the 3d level is achieved through electron transfer from the free-electron-like4sp states to the unhybridized pure 3d spin down states; the latter is lower in energy thanthe 3d–4sp hybridized states. The correlation-induced 6 eV satellite energy is enhanced byAr+ bombardment. These observations make it feasible to gauge the Ni 3d electron populationby probing the 2p photoemission spectra and to modify the supported Ni nano-clustersthrough thermal treatment and/or ion bombardment.

Dynamical Coherent-Potential Approximation and Tight-Binding Linear Muffintin Orbital Approach to Correlated Electron System

Dynamical coherent-potential approximation (CPA) to correlated electrons has been extended to a system with realistic Hamiltonian which consists of the first-principles tight-binding linear muffintin orbital (LMTO) bands and intraatomic Coulomb interactions. Thermodynamic potential and self-consistent equations for Green function are obtained on the basis of the functional integral method and the harmonic approximation which neglects the mode–mode couplings between the dynamical potentials with different frequency. Numerical calculations have been performed for Fe and Ni within the second-order dynamical corrections to the static approximation. The band narrowing of the quasiparticle states and the 6 eV satellite are obtained for Ni at finite temperatures. The theory leads to the Curie–Weiss law for both Fe and Ni. Calculated effective Bohr magneton numbers are 3.0 µ B for Fe and 1.2 µ B for Ni, explaining the experimental data. But calculated Curie temperatures are 2020 K for Fe and 1260 K for Ni, being ...

Electronic structure and effects of dynamical electron correlation in ferromagnetic bcc Fe, fcc Ni, and antiferromagnetic NiO

We have constructed a $\text{LDA}+\text{DMFT}$ method in the framework of the iterative perturbation theory with local density approximation (full-LDA) Hamiltonian without mapping onto the effective Wannier orbitals. We then apply this $\text{LDA}+\text{DMFT}$ method to ferromagnetic bcc Fe and fcc Ni as a test of transition metal, and to antiferromagnetic NiO as an example of transition metal oxide. In Fe and Ni, the width of occupied $3d$ bands is narrower than those in LDA and Ni 6 eV satellite appears. In NiO, the resultant electronic structure is of charge-transfer insulator type and the band gap is 4.3 eV. These results are in good agreement with the experimental x-ray photoemission spectroscopy. The configuration mixing and dynamical correlation effects play a crucial role in these results.

Beam induced reduction of U(VI) during X-ray photoelectron spectroscopy: The utility of the U4f satellite structure for identifying uranium oxidation states in mixed valence uranium oxides

Reduction of U VI by the beam during X-ray photoelectron spectroscopy (XPS) is a commonly observed phenomenon. This can affect the determination of the U oxidation state, or states, in U oxides (or U compounds in general) and compromise the validity of peak parameters derived from U VI oxide standards. However, there is little quantitative information on the reduction kinetics and species produced. The objective of this contribution is to investigate and quantify the effects of X-ray beam reduction of U VI during XPS analysis. Successive U4f XPS spectra were taken over a 26 h period during the X-ray induced reduction of U VI oxy-hydroxide that was precipitated onto the basal plane of mica. In addition, valence band XPS spectra, including the U5f region, were recorded. Factor analysis identified three dominant and, by definition, linearly independent components. Consequently, we fit the U4f level, including the satellite structure, with three components that represented U VI, U V, and U IV. Peak parameters were remarkably stable and consistent with U VI, U V, and U IV over the entire reduction sequence despite the likely formation of a partially covalent mixed-valence U oxide. Although the satellite features for U IV and U V were modified by their bonding environment, they still served well as diagnostic tools for identifying U oxidation states. In particular, the 8 eV satellite appears to be a robust indicator of U V over a range of bonding environments. This is important because the presence of U V might not be necessarily obvious in the primary peak envelope if XPS energy resolution is low and/or U IV–U V binding energy separations are appreciably less than 1 eV. We also discuss insights obtained from modeling the kinetic data for the time evolution of U VI, U V, and U IV.

Ni 2p X-ray photoelectron spectroscopy study of nanostructured nickel oxide

Herein the detailed analysis of the Ni 2p X-ray photoelectron spectra of nanostructured nickel oxide samples with three different average crystallite sizes is reported. The observed main line broadening and the increase in the relative intensity of the ∼1.5 eV satellite structure are discussed taking into account the large surface to volume ratio, high concentration of Ni 2+ vacancies and enhancement in the Ni 3d–O 2p hybridization. The influence of these factors on the possible local and non-local screening mechanisms accompanying the photoemission of Ni 2p core level electron is analyzed on the basis of the Ni 7O 36 cluster calculations.

New interpretations of XPS spectra of nickel metal and oxides

A current interpretation of XPS spectra of Ni metal assumes that the main 6 eV satellite is due to a two hole c3d 94s 2 (c is a core hole) final state effect. We report REELS observation in AES at low voltages of losses (plasmons and inter-band transitions) corresponding to the satellite structures in Ni metal 2p spectra. The satellite near 6 eV is attributed to a predominant surface plasmon loss. A current interpretation of Ni 2p spectra of oxides and other compounds is based on charge transfer assignments of the main peak at 854.6 eV and the broad satellite centred at around 861 eV to the cd 9L and the unscreened cd 8 final-state configurations, respectively (L is a ligand hole). Multiplet splittings have been shown to be necessary for assignment of Fe 2p and Cr 2p spectral profiles and chemical states. The assignments of Ni 2p states are re-examined with intra-atomic multiplet envelopes applied to Ni(OH) 2, NiOOH and NiO spectra. It is shown that the free ion multiplet envelopes for Ni 2+ and Ni 3+ simulate the main line and satellite structures for Ni(OH) 2 and NiOOH. Fitting the NiO Ni 2p spectral profile is not as straightforward as the hydroxide and oxyhydroxide. It may involve contributions from inter-atomic, non-local electronic coupling and screening effects with multiplet structures significantly different from the free ions as found for MnO. A scheme for fitting these spectra using multiplet envelopes is proposed.

Magnetic and XPS studies on TbNi 5–x Al x system

Magnetic measurements were performed on TbNi5–xAlx system, in the temperature range 1.7–300 K. At T = 1.7 K the saturation magnetizations are smaller than gJJ value of Tb. The nickel moments at 0 K, determined by band structure calculations are antiparallely oriented to Tb one and decrease in magnitude, being essentially null for TbNi3Al2 sample. The effective nickel moments vary from 2.10 μB (x = 0) to ≅ 1.10 μB (x = 2). The XPS studies show that the Ni2p core level lines are similar to those of pure Ni, although the intensities of Ni 6 eV satellite decrease. The valence band spectra suggest an increase of the Ni3d–Al3p hybridization, when increasing Al content, in agreement with band structure calculations. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The Mn 2p core-level photoelectron spectrum of Pd–Mn bimetallic systems on Pd(1 0 0)

It is shown that the Mn 2p spectra of Mn atoms in Pd–Mn bimetallic surface systems formed on Pd(1 0 0) exhibit a satellite, separated 1 eV from the main line, in addition to the 5 eV satellite previously observed for Mn-containing compounds and surface alloys. The main line and the low-energy satellite are both assigned to 2p 53d 6 final states whereas the 5 eV satellite is associated with 2p 53d 5 final states. The identification of the two low-binding energy peaks is based on an energy comparison with the Mn 2 p→3 d X-ray absorption spectrum. The relative intensities of the two low-binding energy peaks furthermore vary depending on the Mn atomic environment, reflecting the changes in the properties of the Mn 3d band rather than the geometric position of the Mn atoms. For Mn coverages ≤1 monolayer, the highest degree of Mn 3d localization was found for structures in which the Mn atoms are spread uniformly over the surface. The observed changes in the Mn 2p spectra are discussed in terms of varying Mn–Pd interaction, exchange splitting and magnetic ordering.

Electronic Structure of Nanostructured Nickel Oxide Using Ni 2p XPS Analysis

We examine the electronic structure of nanostructured nickel oxide with an average particle size of 4–5 nm using Ni 2p X-ray photoelectron spectrum. The most striking features of the spectrum are the Ni 2p main line broadening and an increase in the relative intensity of the ∼ 1.5 eV satellite. We explain the observations as due to an enhancement in the non-local screening process on the basis of Ni7O36 cluster model by taking into account the large surface area to volume ratio and high Ni2+ vacancy concentration in nanostructured nickel oxide. The important contribution of an enhanced Ni 3d–O 2p hybridization and the origin of shake-up peaks above the ∼ 7 eV satellite is also discussed. The study underlines the importance of factors such as the actual local environment of the core hole site, defect density and distribution, possible structural transitions, etc. in determining the Ni 2p core level X-ray photoelectron spectrum of nanostructured nickel oxide and shows that the actual synthesis routes and the thermal history greatly influence the electronic structure of nanostructured nickel oxide.

Loss structures in the photoemission spectra of MnO: A careful analysis of peak intensities

A careful and rigorous analysis of the intensities of several features of the Mn $3s$ x-ray photoemission spectra of MnO, including the satellites at 20--30 eV below the main exchange split peaks is carried out. The previous interpretation of the 20--30 eV satellite is that they arose from electron correlation effects relative to the near degeneracy of the atomic levels. Our work shows that loss processes must also be taken into account. In particular, it is shown that only about 60% of the broad 20--30 eV satellite is due to near degeneracy correlation effects, while a contribution from the shakeup and plasmon loss structures constitutes the remaining 40% of the intensities of this feature.

Helicity Dependence of the Spin Polarization of Ni 6 eV Satellite

Spin-resolved photoemission spectra of the 6 eV satellite of ferromagnetic Ni valence band have been measured with circularly polarized light at Ni 3 p core level excitation threshold. We have observed that the spin polarization of the 6 eV satellite was enhanced according to the Δ m =+1 excitation of the dipole selection rule for magnetic quantum numbers and suppressed to the Δ m =-1 excitation. The observed helicity dependence of the spin polarization was discussed based on an atomic model including the spin-orbit interaction.

Observation of the two-hole satellite in Cr and Fe metal by resonant photoemission at the2pabsorption energy

Valence-band spectra of Cr and Fe metal were measured with photon energies around their respective $2p$ energies. An Auger signal is found to be superimposed on the valence-band photoemission signal for photon energies at and above the $2p$ absorption energy, but also for excitation energies down to $\ensuremath{\sim}4$ eV below the $2p$ absorption energy. This is the radiationless resonance Raman (resonant Raman Auger) regime and gives rise to a signal that is equivalent, in terms of the final state, to the 6 eV satellite in Ni with energies at 3.5 eV below ${E}_{\mathrm{F}}$ in Cr and 3.2 eV below ${E}_{\mathrm{F}}$ in Fe.

Correlation between L 3 absorption satellite intensity and spin moment in ultrathin Ni films

Hybridization and magnetism in ultrathin Ni films grown on Co/Cu(001) are studied using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). XAS shows a dramatic decrease in the density of unoccupied Ni d-states as the Ni coverage is reduced from 1 to 0.2 ML. The thickness dependent electronic structure is related to the Ni interface magnetism. Using XMCD sum rule analysis indicates that the increased Ni d-state occupation is accompanied by a sharp decrease in the Ni spin moment. The value of this spin moment is correlated with the 6 eV satellite in the XA spectra and is explained in terms of the configuration interaction model.

On the possibility of observation of electronic states of metallic atomic wire on Ni(001) surface with angle-resolved photoemission

The possibility of the observation of the one-dimensional electronic state on a metallic atomic wire on a metallic surface by using the angle-resolved photoelectron spectrum is investigated. The ARUPS program of the one-step model with the layer KKR method has been used where the so-called ‘6 eV satellite’ is excluded because it is out of the scope of this calculation. The muffin-tin potentials we used were produced using the self-consistent full-potential LMTO method. Nickel atomic wires on a nickel(001) surface have been considered as an example of the atomic wire. A peak about 6 eV below the Fermi level was observed in our calculated spectra. This peak has dispersion only along the direction of the atomic wire and has had no interaction with other atomic wires. Thus, the peak is identified as an isolated one-dimensional electronic state on the atomic wire. The result can be applied to any metallic surfaces.