Ni 3s Research Articles

XPS study of the surface enrichment process of carbon on C-doped Ni(111) using inelastic background analysis

The surface segregation and precipitation mechanism of epitaxially grown graphite (0001) layers on the C-doped Ni(111) surface at various temperatures has been investigated by in-situ XPS measurements and inelastic-background analysis with the Tougaard method. From the C 1s peak intensities as well as the C 1s peak shifts as a function of temperature, we can identify three states corresponding to the presence of individual surface carbon atoms, monolayer graphite, and multilayer graphite. Inelastic-background analysis of C 1s, Ni 3s, 3p, and the valence band energy regions was applied to the monolayer graphite and the growth of the surface-precipitated multilayer-graphite at 1015 K. The observed growth mode was island formation on the pre-existing monolayer graphite, that is, a kind of Stranski-Krastanov growth mode.

Interaction between the LaNi 5-type intermetallic compound and hydrogen sulfide

H 2S interaction with powdered La 0.95Ce 0.05Ni 4.98Al 0.02 has been studied in the temperature range 293–973 K. Sorption experiments were carried out using a flow system with gas stream 3 vol% H 2S in Ar, 1.5 vol% H 2S in Ar and 3% H 2S/60% H 2/37% Ar. Structural changes and surface morphology were studied by X-ray diffraction and scanning electron microscopy. At T = 293 K, large amounts of H 2S were absorbed by the sample without significant changes in its structure, corresponding to x = 4. 5 for La 0.95Ce 0.05Ni 4.98Al 0.02(H 2S) x. At T = 353 K, hydrogen sulfide was also absorbed; however, after the first 100 min of total absorption without any products in the outlet gas, 10–20% H 2 was registered (with regard to amount of H 2S in the initial gas stream). X-ray patterns show the beginning of the formation of Ni 3S 2 and amorphous phase with a diffuse maximum in the range 24–32 ° (2θ, Cu-K α). With T increasing, H 2 content increases and equals 30–40% at T = 433 K and 50% at T = 773 and 973 K. According to XRD, Ni 3S 2. La 2S 3 and initial phase are present. After prolonged testing at 773 K, LaH 2 peaks appeared in X-ray patterns. Electron micrographs show large particle formation with porous flaky sulfides distributed over them. Experimental data for a 3% H 2S/60%/H 2/37% Ar mixture are in agreement with those described above. H 2S is removed from the mixture at T = 773 K while the amount of H 2 is constant. This research was carried out in connection with the problem of refining H 2 produced from natural gas containing H 2S.

Spin-resolved x-ray photoemission from ferromagnetic nickel.

Spin-resolved x-ray photoelectron-spectroscopy (SRXPS) studies of metallic-Ni core-level and valence-band photoemission are reported. Prominent spin polarizations are observed for all main components and satellites. A spin-dependent splitting of 0.38 eV is observed for the main Ni 3s component. The Ni 3s 6-eV satellite, as well as a secondary satellite located \ensuremath{\sim}14 eV from the main 3s peak, both display a nearly 100% majority-spin polarization. Analogous results are found for the Ni 2s level. The 6- and 14-eV satellites are assigned to final states derived from the $^{1}$G and $^{1}$S states, respectively, of a local \ensuremath{\sim}3${\mathit{d}}^{8}$ final-state valence configuration that is created by the shakeup of a \ensuremath{\downarrow}-spin 3d electron to states above ${\mathit{E}}_{\mathit{f}}$. The manifestation of these phenomena in SRXPS studies of the Ni valence band, 3p, 2${\mathit{p}}_{3/2}$, and 2${\mathit{p}}_{1/2}$ core levels is presented and discussed. The SRXPS data are consistent with an itinerant-electron extra-atomic screening model in Ni involving both unoccupied pure 3d states and unoccupied, unpolarized, and hybridized 3d-4sp states. Final-state occupation of these states following photexcitation leads qualitatively to a final-state Ni 3d valence configuration of \ensuremath{\sim}50% 3${\mathit{d}}^{9}$ and \ensuremath{\sim}50% 3${\mathit{d}}^{10}$. The 3${\mathit{d}}^{9}$ configuration is the origin of the satellite production in Ni.

The effect of nickel compounds on immunophenotype and natural killer cell function of normal human lymphocytes

In order to elucidate effects of nickel on human lymphocytes in vitro, peripheral blood mononuclear cells from normal donors were initially tested for viability in the presence of increasing concentrations of two selected nickel salts, sparingly-soluble nickel subsulfide (Ni 3S 2), and promptly-soluble nickel sulfate (NiSO 4). After establishing the toxicity profile, the cells were cultured for 24 h with each compound at three nontoxic concentrations, 0.01 mM, 0.02 mM, and 0.04 mM, to determine its effect on lymphocyte immunophenotype and function. Cells were also cultured in the presence of 0.01–0.04 mM magnesium acetate, Mg(CH 3COO) 3, while still other cell samples were subjected to a mixture of Mg(CH 3COO) 2 plus either Ni 3S 2 or NiSO 4 at equimolar concentration. Following the culture, the immunophenotype of the cells was determined by indirect immunofluorescence, using monoclonal antibodies to major differentiation antigens of peripheral blood mononuclear cells, and their natural killer activity toward K562 target cells was measured. Both nickel salts were found to exert distinct effects on lymphocyte phenotype. Exposure of cells to Ni 3S 2 resulted in the decline of CD4 and natural killer cell populations. NiSO 4 diminished the abundance of natural killer cells and, to a limited extent, also of CD4 cells. The nickel salts tested suppressed natural cytotoxicity of peripheral blood mononuclear cells, with Ni 3S 2 acting more strongly than NiSO 4. The addition of Mg(CH 3COO) 2 to a nickel salt during in vitro culture abolished the above inhibitory effects. Nickel and magnesium salts did not affect CD3, CD8, CD20, and CD11a cell populations. The results indicate that nickel salts have deleterious effects on human peripheral blood mononuclear cells in short-term in vitro culture, but the magnitude of these effects varies, depending on the cell subsets.

The effects of the lithium intercalation on the X-ray photoelectron spectra of NiPS3

A detailed XPS study of the lithium-intercalated NiPS3 specimens was performed at the 2p, 3p, 3s core levels of the nickel atoms and at the 2p core levels of the sulphur and phosphorous atoms for various lithium contents. Comparison of the Ni 2p, 3p and 3s XPS spectra corresponding to NiPS3 and LixNiPS3 systems shows some evident trends. In particular, a shift of the Ni main line towards lower binding energies, a decrease in the intensity of the Ni 3p, 2p satellite structures and a change in the full width at half maximum of the Ni 3s band with lithium content are observed. All these findings suggest a change in the 3d electron configuration for high lithium concentrations. As regards the cluster (P2S6)4−, with the addition of lithium, a P 2p main line shift towards higher binding energies is noted, while the S 2p peak shifts towards lower binding energies. These results are discussed in comparison with previous physical measurements concerning the nickel reduction process and the related electronic modifications.

Phase stability and structural properties of Ni 7 ± δS 6 and Ni 9S 8 Heat capacity and thermodynamic properties of Ni 7S 6 at temperatures from 5 K to 970 K and of Ni 9S 8 from 5 K to 673 K

Two stable solid phases with composition in the range from (45 to 48) moles per cent of S exist for (nickel + sulfur): Ni 9S 8 which disproportionates to Ni 1 - δS and Ni 7 ± δS 6 above T = (709 ± 5) K, and Ni 7 ± δS 6. The latter non-stoichiometric phase forms eutectoidally from Ni 9S 8 and Ni 3S 2 at T = (675 ± 3) K. It is stable in a rather narrow temperature interval and disproportionates to Ni 1 - δS and Ni 3 ± δS 2 at T = (850 ± 2) K. The phases are characterized structurally, and a revised phase diagram is presented. The heat capacity of a sample with composition Ni 7S 6 was determined over the temperature range T = 5 K to 970 K by adiabatic calorimetry. Effects from metastable modifications of the high-temperature phase were observed during thermal analysis, X-ray diffraction, and calorimetry on incompletely equilibrated samples. Thermodynamic-function values for Ni 7S 6 and Ni 9S 8 are presented.

Nickel Monochromated Al K α XPS Spectra from the Physical Electronics Model 5400 Spectrometer

Nickel spectra were measured with the Physical Electronics Model 5400 x-ray photoelectron spectrometer (XPS) using monochromatic Al Kα at five pass energy settings corresponding to analyzer resolutions of 1.34, 0.54, 0.27, 0.13, and 0.067 eV. The specimen is a high purity 4 μm thick nickel foil (99.95%) obtained from the Goodfellow Corporation and was sputter-cleaned by 3 keV Ar ions for 5 min. We present the survey spectrum (binding energy range of 0–1100 eV) measured at an analyzer energy resolution of 1.34 eV. Multiplexes of the Ni 2p (845–895 eV), Ni 3p (58–88 eV), Ni 3s (100–130 eV), Ni 2s (995–1025 eV), valence band region (−5–20 eV), and Ni LVV Auger lines (611–661 eV) were measured at analyzer energy resolutions of 0.54, 0.27, and 0.13 eV. Those of the Ni 2p (847–885 eV), Ni 3p (59–84 eV), valence band region (−3–15 eV), and Ni LVV Auger lines (612–655 eV) were also measured at analyzer energy resolution of 0.067 eV.

Nickel Mg K α XPS Spectra from the Physical Electronics Model 5400 Spectrometer

Nickel by Mg Kα XPS Nickel spectra were measured with the Physical Electronics Model 5400 x-ray photoelectron spectrometer (XPS) using unmonochromatized Mg Kα x rays and four pass energy settings corresponding to analyzer energy resolutions of 1.34, 0.54, 0.27, and 0.13 eV. The specimen is a high purity (99.95%) 4 μm thick nickel foil that was obtained from the Goodfellow Corporation and was sputter-cleaned by 3 keV Ar ions for 5 min. We present the survey spectrum (binding energy range of 0–1100 eV) measured at an analyzer energy resolution of 1.35 eV. Multiplexes of the Ni 2p (845–895 eV), Ni 3p (55–88 eV), Ni 3s (100–130 eV), Ni 2s (995–1025 eV), valence band region (−5–20 eV), and Ni LVV Auger lines (378–428 eV) were measured at analyzer energy resolutions of 0.54, 0.27, and 0.13 eV.

Localized d-d excitations in NiO(100) and CoO(100).

The localized character of the 3d electrons in the antiferromagnetic oxides NiO(100) and CoO(100) has been studied with electron energy-loss spectroscopy at primary energies between 20 and 1200 eV. The spectra of both charge-transfer compounds exhibit weak but sharp loss structures within the insulating gap region due to crystal-field excitations of the 3${\mathit{d}}^{\mathit{n}}$ configuration (${\mathit{d}}^{\mathit{n}}$\ensuremath{\rightarrow}${\mathit{d}}^{\mathit{n}\mathrm{*}}$). These parity forbidden d-d excitations are strongly enhanced at low primary energies due to exchange scattering. Their observed loss intensity depends on the momentum transfer at the scattering process as is shown by angle-dependent measurements. At NiO(100) a surface d state is found that is due to the lower symmetry of the ligand field at the surface. The measurements demonstrate the existence of spin-forbidden exchange excitations $^{3}$${\mathit{A}}_{2\mathit{g}}$\ensuremath{\rightarrow}${(}^{1}$${\mathit{E}}_{\mathit{g}}$${,}^{1}$${\mathit{T}}_{1\mathit{g}}$) in NiO(100) and reveal their excitation energies. A resonant enhancement of all intra-atomic d-d transitions in NiO(100) is found at the Ni 3s excitation threshold. Temperature-dependent measurements up to the N\'eel point show only little influence of the antiferromagnetic ordering on the EELS spectra of NiO(100). The different shapes of the absorption edges due to interatomic d-d transitions across the insulating gaps of NiO(100) and CoO(100) are discussed.

Characterization of nickel-induced mutations

A Chinese hamster ovary cell line (designated AS52) has been used to test the mutagenicity of nickel compounds. This line lacks the endogenous gene for hypoxanthine phosphoribosyl transferase ( HPRT) but contains an inserted bacterial gene coding for the enzyme guanine-hypoxanthine phosphoribosyl transferase ( gpt) which is the targeted locus for selection. Isolated mutants were clonally expanded and analysed utilizing the polymerase chain reaction (PCR) following exposure to ethyl methanesulfonate (EMS), Ni 3S 2, Ni(OH) 2, NiSO 4, and control conditions. Amplification of the gpt locus in normal AS52 cells results in the generation of two distinct bands, both of which have been characterized by restriction enzyme analysis and nucleotide sequencing. The smaller band represents the gpt gene. The larger band contains a large insert of bacterial origin and is non-functional. Analysis of mutants revealed three distinct patterns: (1) both PCR bands remain intact; (2) the smaller DNA band is deleted; (3) both bands are deleted. Mutant analysis was performed with two unique sets of DNA amplification primers with identical results. When compared to spontaneous or EMS induced mutants, those generated by exposure to nickel compounds exhibited an increase in gene deletions relative to point mutations; the extent of which was compound specific: NiSO 4 > Ni(OH) 2 > Ni 3S 2. These results clearly suggest that a variety of genotoxicological mechanisms are involved in the mutagenic activity of nickel compounds

Iron accelerates while magnesium inhibits nickel-induced carcinogenesis in the rat kidney

Effects of magnesium basic carbomate (MgCarb) and metallic iron powder (Fe 0) on nickel subsulfide (Ni 3S 2)-induced carcinogenesis were studied in kidneys of male F344/NCR rats. The rats, 20–40/group, received functions of Ni 3S 2 alone (62 μmol Ni or with equimolar doses of MgCarb or Fe 0 into the renal cortex of each pole of the right kidney. Control rats were given MgCarb, Fe 0, or 0.1 ml of 50% aqueous glycerol, the injection vehicle. Final incidence of renal tumors 2 years later the injection of Ni 3S 2 alone or mixed with FE 0 was 60%. However, rats given Ni 3S 2 + Fe 0 developmed renal tumours much more rapidly. In contrast, the incidence of renal tumors in rats given Ni 3S 2 + MgCarb was only 20% ( P < 0.01 vs. Ni 3S 2 alone). No kidney tumors were observed in the control rats. Between weeks 4 and 32 post injection Ni 3S 2 alone caused erythrocytes. This effect was attenuated by Fe 0, but not by MgCarb. Hence, there is no firm correlation between carcinogenecity activity of nikel and its ability to induced erythropoiesis. All kidney tumors were of mesenchymal cell origin and resembled the sarcomatous variant of the classic rat renal mesenchymal tumor. Some of them metastatized to the lungs and other organs. In 3–35 days post-injection , kidneys of rats treated with Ni 3S 2 alone showed moderate to extensive necrosis, inflammation, fibrosis, and degenerative and regenerative proliferative changes in the proximal tubular epithelium at the injection site. Similar, but more severe and multifocal changes were observed in the kidneys of Ni 3S 2 + Fe 0-treated rats. The necrosis was less severe in kidneys injected with Ni 3S 2 + MgCarb, but fibrosis and degenerative and regenerative changes in proximal tubular epithelium were similar to those observed in other treatment groups. Ni 3S 2 deposits were seen inside macropahges and proximal tubular epithelial cells of Ni 3S 2 and Ni 3S 2 + Fe 0-treated kidneys more frequently than in Ni 3S 2 + MgCarb-treated kidneys. Thus, magnesium antagonizes nickel carcinogenesis in the rat kidney while iron tends to enhance it. This result may be related to respectively attenuating or enhancing effects of magnesium and iron on the inflammatory response to Ni 3S 2.

Electronic correlation effects in the Ni 3s and Co 3s X-ray photoelectron spectra of NiO, CoO, K 2NiF 4 and K 2CoF 4

A new impurity-cluster configuration-interaction model that treats charge transfer and exchange correlations on the same footing is applied to interpret the 3s core-level X-ray photoelectron spectra of NiO, CoO, K 2NiF 4 and K 2CoF 4. The interplay between charge transfer and exchange correlations in determing the final state satellite structures is clarified and an estimate of the exchange integrals between the 3s hole and the 3d electrons is given. The results are consistent with the electronegativity scale, as regards charge transfer energy, and with the trend suggested by the Van Vleck rule, as concerns the exchange integrals.

Transformation of rat tracheal epithelial cells to immortal growth variants by particulate and soluble nickel compounds

The cytotoxicity and transforming activity of nickel subsulfide, nickel oxide and nickel sulfate was studied by assays of colony-forming efficiency and of transformation of rat tracheal epithelial (RTE) cells to enhanced growth variants (EGVs) and immortal growth variants (IGVs). Nickel subsulfide caused dose-dependent cytotoxicity between 1 and 5 μg/ml, whereas the cytotoxic range of nickel oxide and nickel sulfate was 50–200 μg/ml and 60–130 μg/ml, respectively. At lower concentrations, nickel sulfate caused modest (up to 126%) growth stimulation. During the initial 24-h treatment period, internalized nickel subsulfide particles were observed in phagocytic vesicles in cells near the periphery of all RTE cell colonies, whereas nickel oxide particles were not internalized but had adhered to both the cells and the tissue culture dish. After 7–10 days of the transformation assay, nickel subsulfide particles were no longer visible, but nickel oxide particles remained on the dish for the duration of the 5 week assay. During weeks 3–5 of the transformation assay, internalized nickel oxide particles were observed in non-vacuolated cells at the periphery of the colonies. All 3 nickel compounds significantly ( p < 0.05) increased the transformation frequency of RTE cells to EGVs at moderately cytotoxic concentrations; the order of potency was Ni 3S 2 > NiO = NiSO 4. MNNG, the positive control, was twice as active as nickel subsulfide at 1 3 the concentration and 1 6 the duration of treatment. EGVs induced by MNNG, nickel subsulfide and nickel sulfate were cloned and converted to IGVs at frequencies of 44, 24 and 43%, respectively. In contrast, EGVs transformed by nickel oxide rarely converted to IGVs (13%). All nickel-induced IGVs were immunohistochemically epithelial, mitotically active, aneuploid and exhibited high plating efficiencies. Our results suggest that respiratory epithelial cells are targets for the transforming capabilities of several nickel compounds but that the potency and mechanism of transformation by various forms of nickel may be different according to the physico-chemical properties of each compound.

Mutagenic responses of nickel oxides and nickel sulfides in Chinese hamster V79 cell lines at the xanthine-guanidine phosphoribosyl transferase locus

Mutagenesis of several insoluble nickel compounds-crystalline nickel sulfide NiS, nickel subsulfide Ni 3S 2, nickel oxides (black and green) and soluble NiCl 2 was studied in three Chinese hamster cell lines - at the hrpt gene of the well-defined V79 cell line, and at gpt in two transgenic derivative cell lines G12 and G10. The transgenic cell line G12 responded very strongly to the insoluble Ni compounds, such that the gpt mutagenesis was at least 20 times higher than the spontaneous mutagenesis and in some experiments was even higher. In contrast the response of the G10 cells was much lower - the mutant frequencies only increased 2–3 times over the controls. In V79 cells, NiS and NiO (black) did not induce a mutagenic response at hprt. Soluble NiCl 2 also exhibited no mutagenic activity in V79 cells and induced considerably lower activity than the insoluble compounds in the transgenic G12 cells. Following vitamin E pretreatment of G12 cells for 24 h prior to nickel exposure, increased cell survival was observed for several insoluble Ni compounds whereas vitamin E had no effect on NiCl 2 cytoxicity. With vitamin E pretreatment, significantly lower mutagenic responses in G12 cells were also noted for some insoluble Ni compounds, while no such effect was observed for NiCl 2.

Nickel Induces Increased Oxidants in Intact Cultured Mammalian Cells as Detected by Dichlorofluorescein Fluorescence

Exposure of intact cultured Chinese hamster ovary (CHO) cells to water-soluble nickel (Ni) salts and to relatively water-insoluble crystalline nickel subsulfide (Ni 3S 2) resulted in an increased formation of the fluorescent oxidized compound, dichlorofluorescein (DCF) from the parent nonfluorescent compound, 2,7-dichlorofluorescin diacetate. This fluorescent product was also formed in vitro following oxidation with relatively strong oxidants such as hydrogen peroxide in the presence of peroxidase, suggesting that Ni increased the concentration of hydrogen peroxide in intact cells. However, formation of other strong oxidants such as hydroperoxides is possible since they have also been shown to cause the oxidation of the nonfluorescent dichlorofluorescin to the fluorescent product DCF in vitro. Localization of the oxidized fluorescent DCF in intact cells was also examined by fluorescence microscopy. Both Ni 3S 2 and NiCl 2 appeared to increase the degree of fluorescence in intact CHO cells around the nuclear membranes. This increase in fluorescence was greater in the presence of relatively water-insoluble Ni 3S 2 than water-soluble NiCl 2. These results add to the emerging concept that Ni-induced genotoxicity may be mediated by oxygen radical intermediates.

Final state effects for the core-level XPS spectra of NiO

Ionization of the Ni 3s core level in NiO has been studied using ab initio wavefunctions for an NiO 6 cluster model. Three important final state effects are studied: (1) ligand to Ni 3d charge transfer, (2) exchange coupling of the ionized core level within the open 3d shell; and (3) atomic correlation effects among the metal 3s, 3p and 3d shells. Analysis of the cluster wavefunctions shows that these mechanisms are strongly coupled and must be treated on an equal footing. The ligand to metal charge transfer is often fractional, i.e. intermediate between 0 and 1.

Synthesis and Characterization of Ni 3S 2 Single Crystals

The synthesis and growth of single crystals of Ni 3S 2 are described. Structural information is provided on the room-temperature configuration of this compound. Measurements of electrical resistivity, magnetic susceptibility, and heat capacity below room temperature have been carried out and are briefly discussed. The material may be classified as a good metallic conductor.

Syntheses of Ni 3S 2, Co 9S 8, and ZnS by the decomposition of diethyldithiocarbamate complexes

Three useful sulfides, Ni 3S 2, Co 9S 8, and ZnS, have been prepared by the decomposition of their respective diethyldithiocarbamate complexes. The products were characterized by X-ray diffraction analysis, crystallite size determination, and magnetic susceptibility measurements. The problems associated with organometallic precursors for the synthesis of metal sulfides are discussed and the method is compared with the direct conversion of sulfate salts to sulfides in a controlledH 2/H 2S environment.

Electronic structure and properties of nickel clusters: Ni 6, Ni 8, Ni 19, and Ni 44

All-electron, spin-polarized, LCGTO-LDF calculations have been performed on Ni clusters with face-centered-cubic (and simple cubic) geometry. The results are discussed in relation to theoretical and experimental data for gas-phase Ni clusters and for the extended metal. We analyze bonding, magnetic behaviour, cohesive energy, bond distances, ionization potentials, and DOS profiles, paying particular attention to the role of the Ni 4s and 3d electrons.

The standard molar enthalpy of formation of heazlewoodite Ni 3S 2 determined by its synthesis in a calorimeter

A method has been developed for the synthesis of a binary compound in a calorimeter. A non-traditional method was used to initiate a reaction: chemical components were heated with the energy of a light pulse. Such a method minimized the quantity of energy which was put into the calorimetric system. Precision of the determination of the quantity of initiating energy was gained in this way. The energy of reaction between nickel and sulfur to give crystalline Ni3S2 (heazlewoodite) was measured. The corresponding standard molar enthalpy of formation at 298.15 K is −(226.6 ± 2.2) kJ · mol−1. Possible applications of the method to calorimetric investigations of other materials are discussed.