The effect of the next nearest neighbor ion on the X-ray photoelectron spectra of 2p levels for Co2+, Ni2+ and Cu2+ in MgO

The X-ray photoelectron spectra of Co, Ni and Cu 2p levels for samples of M_xMg_1-xO (M = Co, Ni, Cu), CoO, NiO and CuO were compared. The binding energies of metal 2p_{$\text{3}\text{2}$} levels did not change with their concentration. The shake-up satellite main peak intensity ratios and FWHM of metal 2p levels for Co²⁺ and Cu²⁺ in MgO were smaller than those for CoO and CuO. The Ni 2p_{$\text{3}\text{2}$} spectrum for Ni²⁺ in MgO had no shoulder, unlike NiO. Results indicate that next nearest neighbor ions (metal ions) may influence the final states after photoelectron ejection.     

(II) Infrared and X-ray photoelectron spectroscopy of some transition metal dithiocarbamates and xanthates

Measurements are presented for the binding energy variations of (a) (Ni, Cu) 2p_{$\text{3}\text{2}$}, S 2p and N 1s core levels in a series of Ni and Cu disubstituted dithiocarbamates and (b) (Ni, Cu) 2p_{$\text{3}\text{2}$}, and S 2p core levels in a series of Ni xanthates. These shifts, which are observed to be negative and quite large for the S 2p levels, are then correlated with the infrared absorption frequency variations for the associated intramolecular stretching vibrations of the same series. The results are interpreted in terms of a model based on atomic charges and their potential effects on both variations. The functional relationships between the binding energy and infrared frequency variations are shown to be in good agreement with the experimental results.     

Systematics of core line asymmetries in XPS spectra of Ni

Core line asymmetries have been observed in the 3p_{$\text{1}\text{2}$}, 3p_{$\text{3}\text{2}$}, 3s, 2p_{$\text{1}\text{2}$} and 2p_{$\text{3}\text{2}$} XPS spectra of Ni. The asymmetry parameters are the same for all lines within the experimental accuracy. The absence of exchange splitting in the 3s line indicates a 3d¹⁰ configuration for the fully screened final state of Ni.     

An X-ray photoelectron spectroscopic study of some nickel (II) amine complexes

The X-ray photoelectron (XPS) spectra of several Ni(II) diamine complexes, a Ni(II) triamine complex and several Ni(II) diimine complexes are reported in terms of the Ni 2p, Cl 2p and N 1s core level binding energies. Theoretical models are presented to account for the quadratic relationship observed between XPS Ni 2p_{$\text{3}\text{2}$}binding energy shifts and the N-H infrared rocking frequency as related to these complexes. On the basis of this correlation, it is possible to discriminate between free counter-ions coordinated to the metal or involved in cluster-ion formation. Individual XPS data for these complexes are interpreted in terms of the intrinsic nature of the metal environment and an attempt is made to calculate the metal and donor nitrogen atomic charges for selected complexes.     

Angular distributions of auger electron emission: Clean and gas-adsorbed polycrystalline Ni surfaces

The excitation angle (β) and emission angle (θ) dependences of the Ni M₂,₃VV (61 eV) and Ni L₃VV (850 eV) Auger emissions from clean polycrystalline Ni surfaces, and the S L₂, ₃ M₂, ₃M₂, ₃ (150 eV) Auger emission from S-adsorbed poly-Ni surfaces have been investigated. In the case of Ni (61 eV) and S Auger emissions, the β-dependence shows the $\text{1}\text{cos β}$ distribution, while a significant deviation from $\text{1}\text{cos β}$ is observed for Ni (850 eV) Auger emission. The cosθ distribution and the intermediate between isotropic and cosθ distributions are observed for Ni (61 eV), and for Ni (850 eV) and S Auger emissions, respectively. Those results have been found to be in fairly good agreement with the calculations based on the simple continuum model without consideration of the diffraction effect and the inherent anisotropic emission.     

Proton-neutron correlations in nuclei with N = 30

Structure of the nuclei with N = 30 and Z = 20–28 is investigated by the nuclear shell model within the proton-neutron configurations (1f_{$\text{7}\text{2}$})^z?20_p × (2p_{$\text{3}\text{2}$}, 2p_{$\text{case1}\text{2}$}, 1f_{$\text{case5}\text{2}$})²_n. Effective proton-neutron interactions determined by a least-squares fit to the observed spectra of N = 29 nuclei are adopted. Agreement of the calculated spectra with experimental spectra is satisfactory. Strong correlations between protons and neutrons break down the pairing scheme and lower the first J = 2 levels in doubly even nuclei, which is shown from the resultant wave functions. A relation between the shell model and collective rotational model is discussed concerning the calculated rotation-like spectrum of ⁵⁶Fe. Electromagnetic properties and spectroscopic factors of single-nucleon transfer reactions are calculated. They are in good agreement with experiments.     

Polarization transfer in the deuteron break-up reaction at 56 MeV

The polarization transfer coefficients K^yy′ of the break-up spectra in the reactions ¹²C, ⁵⁸Ni, ²⁰⁹Bi($\text{d}$, $\text{p}$X) were measured at 56 MeV. In the forwardd angles (13.5° and 20.0°), the K_y^y′ data at the break-up peak are nearly equal to $\text{2}\text{3}$ (the spectator model prediction) and they decrease at both sides of the peak. The deviation due to the deuteron D-state is estimated, using PWBA and DWBA.     

Nuclear g-factor of the 172+ isomeric state in 63Cu

The nuclear g-factor of the 4498 keV $\text{17}\text{2}$⁺ isomeric state in ⁶³Cu was measured with the in-bearn perturbed angular distribution method, through the ⁶²Ni(α, p2nγ)⁶³Cu reaction, to be g_exp = 0.184 ± 0.012. This value is in good agreement with a semiempirical g-factor for the three-quasiparticle configuration [π2p_{$\text{3}\text{2}$}(v1f_{$\text{5}\text{2}$}, 1g_{$\text{9}\text{2}$})₇]_{$\text{17}\text{2}$⁺} calculated using the experimental single-particle g-factors of neighbouring nuclei. At the same time the internal magnetic field at the Cu nuclei in Ni metal was obtained to be B_int = ?46.6 ± 1.3 kG.     

Relative Cl 2p:P 2s photoionization intensities in transition metal complexes

X-ray photoelectron spectra of the Cl 2p_{$\text{1}\text{2}$, $\text{3}\text{2}$}, P 2s region were obtained for nine transition metal complexes. The Cl:P atom ratios ranged from 1:3 to 3:2 and exhibited a linear relationship with the Cl 2p_{$\text{1}\text{2}$, $\text{3}\text{2}$} : P 2s intensities. Using AlKα radiation, the ratio of the Cl 2p: P 2s photoionization intensities was found to be 2.5: 1.0 with the McPherson ESCA-36 Photoelectron Spectrometer operated in its standard configuration.     

Étude par esca du cobalt ou du molybdène déposé sur alumine: Analyse quantitative du recouvrement et mise en évidence d'états d'adsorption spécifique des cations

X-ray photoelectron spectra of the Co 2p_{$\text{1}\text{2}$}, and Mo 3d_{$\text{5}\text{2}$} levels for catalysts containing cobalt and molybdenum supported on alumina have been studied. Binding energies and relative peak areas have been investigated in detail in order to establish the formal metal oxidation states and environment of cobalt and molybdenum cations supported on alumina. Before a monolayer has been formed, only tetrahedric sites of alumina are occupied by Co²⁺ cations. After the monolayer has been formed, heterogeneous oxide Co₃O₄ appears. Both tetrahedral and octahedral sites of alumina are occupied by the molybdenum cation in the 6+ formal oxidation state.     

Integral rotation of 32− levels in 65Zn and 67Zn

Low-lying levels of ⁶⁵Zn and ⁶⁷Zn were excited by the Ni(α, n) reaction using enriched Ni and Ni₁₀Fe₉₀ targets. From the angular distributions of gamma rays, E2/M1 mixing ratios were obtained. In the iron alloy targets, integral spin precession was observed and used to measure the g-factors of two $\text{3}\text{2}{}^{\mathrm{?}}$ levels of ⁶⁵Zn. The results are discussed in terms of the shell and unified models of the odd Zn isotopes.     

Low binding energy satellites in the 3d X-ray photoelectron spectra of rare earths (R) in RMn2Si2 and RGa2

The 3_d core-level X-ray photoelectron spectra of rare earths (R) in RMn₂Si₂ (R = Pr, Nd, Sm, Gd) and RGa₂ (R = Pr, Nd, Sm) have been recorded. A structure has been detected on the low binding energy side of each of the 3d_{$\text{5}\text{2}$} and 3d_{$\text{3}\text{2}$} photoemission peaks. The structure identified as a shake-down satellite shows no chemical shift. The energy separation of the satellite has been measured with respect to the main 3d_{$\text{5}\text{2}$} peak. The present results have been examined in the light of recent experimental and theoretical reports.     

H2O adsorption on Ni(100): Evidence for oriented water dimers

H₂O adsorption on clean Ni(110) surfaces at T ≦ 150 K leads at coverages below $\text{θ ? 0.5}$ to the formation of chemisorbed water dimers, bound to the Ni substrate via both oxygen atoms. The linear hydrogen bond axis is oriented parallel to the [001] surface directions. With increasing H₂O coverage $\text{(θ ≧ 0.5)}$, the accumulation of further hydrogen bonded water molecules induces some modification of the dimer configuration, producing at $\text{θ ? 1}$ a two-dimensional hydrogen bonded network with a slightly distorted ice lattice structure and long range order.     

Mössbauer study of the modified pyrochlores CsMFeF6 (M = Mn,Ni)

⁵⁷Fe Mössbauer spectra of the modified pyrochlores CsMFeF₆ (M = Mn, Ni) were obtained between 1.5 K and room temperature. The spectra for single crystal and powder absorbers are very similar, and demonstrate the randomness associated with the iron sites. Nevertheless, the presence of two distinct iron sites, recently reported by Varret and Courbion for powder samples, is confirmed. Both CsMnFeF₆ and CsNiFeF₆ are antiferromagnets with Néel temperatures, T_N, of 25 and 5.2 K, respectively. The hyperfine fields lie on the Brillouin function with $\text{S =}\text{5}\text{2}$. The hyperfine parameters show that the iron ions are ferric in the high-spin state.     

Study of the 58Ni(τ, α)57Ni reaction at 25 MeV

The ⁵⁸Ni(τ, α)⁵⁷Ni reaction has been studied at 25 MeV incident energy. Angular distributions have been measured from 5° to 50° with a split-pole spectrometer up to 13.5 MeV excitation energy. A local zero-range DWBA analysis has been carried out, allowing l-assignments for about eighty levels, most of them previously unknown. An isospin-dependent potential has been used in the calculation of the neutron form factor for both T_<and T_> states, and the C²S values deduced using this procedure are compared to those obtained with the usual separation energy method. Analog states of eleven ⁵⁷Co levels have been identified and the eventuality for isospin mixing in ⁵⁷Ni has been discussed. A sum rule analysis has been carried out and energy centroids of hole states have been determined. About 60% of the $\text{1}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{and}\text{2}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{T}{}_{\mathrm{<}}$ strengths and the full $\text{1}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{1}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ hole strengths are observed. It is shown that the two excess neutrons in the ⁵⁸Ni ground state mainly populate the $\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{, 1}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{and}\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ orbitals, whereas the occupancy number of the $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ subshell is found to be smaller than 0.1%. Some non-pickup angular distributions have also been observed and a CRC analysis assuming two-step processes in the (τ, α) reaction and weak-coupling wave functions for final states has been attempted. Assignments of J^π values are proposed for four ⁵⁷Ni levels, based on this analysis.     

E.S.R. and optical study of the interstitial h centres in heavily neutron irradiated Lif

The paramagnetic spectra of the hole-centres created in LiF by a heavy neutron irradiation at 78°K have been studied by E.S.R. and optical techniques. Samples which have been irradiated at a dose at least equal to $\text{10}{}^{19}\text{solneutrons}\text{cm}{}^2\text{exhibit}$, after they have been warmed at 200°K, several spectra related to 〈111〉-oriented asymmetric centres. These centres are stable up to 500°K. One of them, designated the H_N1 centre, has been studied in detail. The analysis of the paramagnetic spectrum shows that this defect is an interstitial fluorine atom which forms an asymmetric ($\text{F}{}^{\mathrm{<mtext>-</mtext><mtext>?1</mtext><mtext>3</mtext>}}\text{- F}{}^{\mathrm{<mtext>-</mtext><mtext>?2</mtext><mtext>3</mtext>}}$) molecule ion with a lattice fluorine ion. Optical experiments have shown that the excited Σ level is at 4.1 eV from the ground Σ level. Two excited π levels have been found at 2.5 and 2.1 eV. This asymmetric H centre is formed from a primary symmetric H centre, designated the H_N2 centre. The H_N2 centre is 〈110〉-oriented. The transformation of the symmetric H_N2 centre into the asymmetric H_N1 one is associated with important changes in the values of the isotropic hyperfine interaction and of the g_⊥ shift.     

Core-level reflectance spectroscopy of germanium by means of synchrotron radiation

Reflectance spectra due to 3d core-levels of Ge have been measured in the photon-energy region from 29 to 38 eV by means of synchrotron radiation. Second-energy-derivative spectra have newly shown pairs of doublet structures with energy separation of the Ge $\text{3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{?}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ core-level splitting. The observed doublet structures are assigned to the transitions from the $\text{3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ and $\text{3d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ core-levels to the flat regions of the conduction band around the particular symmetry points of Δ₆^c and L(₃^c(L₆^c, L_4,5^c).     

Electrical conductivity and defect structure of Ni-doped and “CO-reduced” Ni-doped SrTiO3 single crystals

The electrical conductivities of Ni-doped and “CO-reduced” Ni-doped SrTiO₃ single crystals were measured at temperatures 700–1200°C and P_o2's of 10^?7–10^?1 atm. Plots of log σ vs $\text{1}\text{T}$ at constant P_o2's were found to be linear, and the activation energies appeared to be 0.92 eV for Ni-doped SrTiO₃ and 0.50 eV for “CO-reduced” Ni-doped SrTiO₃ single crystals, respectively. Plots of log σ vs log P_o2 at constant temperature were found to be linear with an average slope of ?$\text{1}\text{4}$ for SrTiO₃:Ni and of ?$\text{1}\text{6}$ for “CO-reduced” SrTiO₃:Ni single crystals, respectively. The electrical conductivity dependencies on P_o2 indicate that a triply ionized titanium interstitial and an oxygen vacancy model are applicable to Nidoped and “CO-reduced” Ni-doped SrTiO₃ single crystals, respectively. The small polaron conduction was suggested on “CO-reduced” Ni-doped SrTiO₃ single crystal from the temperature dependence of conductivity.