Core level excitations in the lanthanides by electron energy loss spectroscopy. I. 4d and 3d excitations

Strasser, G.; Rosina, G.; Matthew, J.A.D.; Netzer, H.

doi:10.1088/0305-4608/15/3/025

Cited by 48 publications

(17 citation statements)

References 21 publications

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“…All three spectra show evidence of minor peaks at lower loss energies. Felton et a1 [7] and Strasser et a1 [40] have published electron energy loss spectra for clean europium and oxygenexposed europium that agree well with the spectra of Eu metal and Eu203, respectively, displayed in figure 6. The 2.5 eV shift in the position of the main loss peak, which is observed when the number of 4f electrons changes from seven (Eu and EuA1,) to six (Eu203), provides a signature of the europium oxidation state [38].…”

Section: Electron-impact-excited Spectra Of Eu Eual and Eu203supporting

confidence: 56%

“…[Kr]4d95s25p64f"Vn* Gf1 transition [ l l , 12, 401. The most intense discrete resonance peaks of Eu metal occur at 135 and 132 eV, in both photoabsorption and electron energy loss spectra [12,19,31,40]. These excitations are predicted, using equation (l), to result in 4f(4d t 4f) direct recombination emission at 129 and 126 eV, respectively, in good agreement with experiment.…”

Section: Discussionmentioning

confidence: 63%

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Electron spectroscopy of europium

Hocking¹,

Matthew²

1990

J. Phys.: Condens. Matter

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Electron emission spectra of ELI, EuAI2 and EuzO3 arising from excitation of the europium 4d subshell by 0.5-5 keV electron impact and A1 K a x-radiation have been compared. The electron-impact-excited emission structure has been assigned primarily to the N45023023, N45023N67 and N,&,N67 normal Auger transitions and the 4f(4d + 4f) direct recombination process; Auger transitions with a G f spectator electron and the 5p(4d c 4f) direct recombination process appear to be of secondary importance. Europium4d -+ 4f giant resonance excitation has been monitored by electron energy loss spectroscopy and correlated with the direct recombination features. The electron emission excited by A1 K a x-radiation has been shown to be predominantly due to Auger transitions with a spectator vacancy: N45N-N023023, N,5N-N023N6, and N45N-NN67N67. Argon-ion bombardment of europium has been found to excite normal 4d-based Auger electron emission but not direct recombination electron emission.

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Section: Electron-impact-excited Spectra Of Eu Eual and Eu203supporting

confidence: 56%

Section: Discussionmentioning

confidence: 63%

Electron spectroscopy of europium

Hocking¹,

Matthew²

1990

J. Phys.: Condens. Matter

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“…Our present approach involves the application of core-level electron energy loss spectroscopy (CEELS) and, to a lesser extent, auger electron spectroscopy (AES) and focuses on (i) the identification of 2p core electronic levels in the bisulfate adlattice as referenced to the energy levels in sodium sulfate and (ii) loss spectra from 4f 7/2 levels in platinum and the electrode potential effect in these loss spectra. As is well known, ,− in the core-level electron energy loss spectroscopy a monochromatic incident electron interacts with an inner shell electron of the target atoms and lifts the core-level electron to a final (empty) state above the Fermi level. The loss energy (Δ E ) is given by Δ E = E p − E k , where E p is the incident electron energy and E k is the kinetic energy of the outgoing electron.…”

Section: Introductionmentioning

confidence: 99%

Specific Adsorption of a Bisulfate Anion on a Pt(111) Electrode. Ultrahigh Vacuum Spectroscopic and Cyclic Voltammetric Study

et al. 1996

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We addressed in this study the process of specific adsorption of anions at the metal/solution interface. We focused on the nature of the surface chemical bond that accounted for the phenomenon of adsorption specificity in the context of bisulfate coverage and structural information. While we limited our investigations to bisulfate adsorption on the Pt(111) electrode in sulfuric and mixed sulfuric/perchloric acid media, our conclusions have general significance in explaining ionic adsorption events in electrochemistry. We used core-level electron energy loss spectroscopy, auger electron spectroscopy, low energy electron diffraction, and cyclic voltammetry. Our findings show that in the studied range of sulfuric acid concentration (10-4−10-1 M) the maximum anion coverage is 0.34 ± 0.02 monolayer (ML) and that this coverage corresponds to a highly ordered Pt(111)(√3 × √3)R30° surface structure. S2p core-level and LMM Auger electron spectra indicate that the chemical state of bisulfate sulfur is +6, as in the sulfate anion in a sulfate salt matrix. However, the electron density on the adlattice sulfur is higher than in the salt, evidently due to back-donation of electrons from the substrate to the adsorbate. We conclude that backdonation plays a major role in binding the anions to the surface. Further, the plot of the back-donated electron density vs electrode potential assumes a distorted parabolic shape. The descending parabola branch covers the potential range where bisulfate adsorption increases with potential, and a flat minimum coincides with the double layer potential range. When OH adsorption and platinum oxidation begin, a 2D compressive effect of the O-type adsorbates causes the bisulfate−platinum O−Pt bond to be sequentially cleaved. The “flow” of metal electrons to the adsorbate is therefore reduced, and the S2p loss energy approaches the level characteristic of sodium sulfate unperturbed by surface interactions. Loss spectra from Pt4f7/2 confirm that the oxidized surface is emersed to vacuum but in the double layer potential range fail to respond to either the electrode potential change or the bisulfate adsorption.

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“…Figure 10 shows the second-derivative Ce N 4,5 ISEELS spectra in Cu x CeNb 2 S 5 and CeNbS 3 , which are compared with the energy-distribution curve of metal Ce that has been measured by Strasser et al 23 and the calculated of Sugar 24 ͑solid lines͒ and Nuroh 25 ͑broken lines͒ which have been obtained for Ce 3ϩ , while taking into account the multiplet structures arising from the exchange interaction among localized 4 f electrons and a 4d core hole into account. In the calculation of Sugar only optically allowed transitions are taken into account to compared with the XAS spectrum, whereas in the calculation of Nuroh, optically forbidden transitions as well as optically allowed transitions are involved to take account for the breakdown of dipole selection rules at large momentum transfer, which as encountered in ISEELS.…”

Section: B Xps and Iseels Resultsmentioning

confidence: 99%

Crystal growth and characterization of Cu-intercalated misfit-layer compounds

Ohno

1996

Phys. Rev. B

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Single crystals of Cu x CeNb 2 S 5 (xϷ0.6) are grown by chemical-vapor-transport reaction of powder mixture of Cu and CeNb 2 S 5 . The compound is regarded as a Cu intercalation derivative of a second-stage misfit-layer compound with incommensurate planar intergrowth structure of CeS and Cu x ͑NbS 2 ͒ 2 layers. Two sublattices for CeS and Cu x ͑NbS 2 ͒ 2 layers have a different geometry in the a-b plane although the stacking direction coincides with the c axis. Lattice parameters are a 1 ϭ5.80 Å, b 1 ϭ5.80 Å, and c 1 ϭ17.93 Å for CeS layers and a 2 ϭ3.35 Å and c 2 ϭ1.93 Å for Cu x ͑NbS 2 ͒ 2 layers, where a 1 ϭͱ3a 2 . The composite crystals, which are represented by ͓Cu x CeNb 2 S 5 ͔ z ͓Cu y NbS 2 ͔ 1Ϫz , ͓Cu x SmNb 2 S 5 ͔ z ͓Cu y NbS 2 ͔ 1Ϫz , and ͓SnNbS 3 ͔ z ͓Cu y NbS 2 ͔ 1Ϫz , are also grown by a similar method. The single and the composite crystals are, respectively, formed by regular and irregular stacking of Cu and MS ͑MϭCe, Sm, and Sn͒ layers. The electronic structures are studied by means of x-ray photoemission spectroscopy and inner-shell-electron energy-loss spectroscopy methods.

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Core level excitations in the lanthanides by electron energy loss spectroscopy. I. 4d and 3d excitations

Cited by 48 publications

References 21 publications

Electron spectroscopy of europium

Electron spectroscopy of europium

Specific Adsorption of a Bisulfate Anion on a Pt(111) Electrode. Ultrahigh Vacuum Spectroscopic and Cyclic Voltammetric Study

Crystal growth and characterization of Cu-intercalated misfit-layer compounds

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