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| 2. |
- Finazzi, M., et al.
(författare)
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Multiatomic resonant photoemission spectroscopy on CuO and NiO : Observation of antiresonant behavior
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 62:24, s. R16215-R16218
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Tidskriftsartikel (refereegranskat)abstract
- The intensity of the O 1s core photoemission peak has been measured for CuO and NiO as the photon energy is scanned across the L-3 absorption edge of the metal ion. In CuO, the O 1s peak shows a typical antiresonant behavior, with a sizable decrease of its cross section at photon energies below the Cu L-3 threshold. No detectable effect is observed for NiO. The CuO data are well reproduced by a multiatom resonant photoemission model based on resonant light scattering.
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| 3. |
- Finazzi, M., et al.
(författare)
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Photon energy dependence of the perpendicular geometry magnetic circular dichroism in the 2p3p3p resonant photoemission from Ni
- 2000
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 12:9, s. 2123-2133
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic circular dichroism in the perpendicular geometry of the resonant 2p3p3p photoemission (PE) spectroscopy has been investigated in metallic Ni as a function of the photon energy across the Ni Lj absorption edge. Within the experimental error bars, the photon energy dependence of the PE dichroism signal is the same as the one shown by the magnetic circular dichroism of the corresponding x-ray absorption (XMCD), obtained in the collinear geometry. This is attributed to the fact that, in metal Ni, the orbital [L-z] and dipolar [T-z] moments are smaller than the spin angular moment [S-z]. The latter is the dominating term in both the expressions that give the integrated values of the PE dichroism or XMCD intensities, Although the respective photon energy dependence is very similar, the normalized PE dichroism intensity is a factor similar to 5.6 smaller than the normalized XMCD signal, while only a factor similar to 1.6 is expected from theoretical considerations. This factor is observed even below the L-3 threshold, thus we exclude that the small intensity of the perpendicular geometry dichroism in the Ni 2p3p3p resonant photoemission is due to fast relaxation processes in the intermediate state.
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| 4. |
- Finazzi, M., et al.
(författare)
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Radiationless Raman versus Anger behavior at the Cu L-3 resonance of CuO and Cu2O
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 61:7, s. 4629-4635
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the behavior of the 2p3p3p and 2p3s3p Anger lines of CuO and Cu2O scanning the photon energy across the Cu L-3 resonance. For both samples, when the excitation energy is below the L-3 resonance, we observe the 2p3p3p and 2p3s3p peaks at constant binding energy. This behavior is typical of nonradiative resonant Raman scattering. If the photon energy is raised above the L-3 maximum, the two samples behave in different ways. In CuO, the Auger peaks are always observed at constant binding energy, while in Cu2O their kinetic energy first reaches a maximum at correspondence with the absorption threshold, and then stabilizes at a value slightly higher than the off-resonance Auger peaks. These differences are interpreted in terms of the different electronic structure of the Auger intermediate state at resonance. In CuO, the intermediate state corresponds to a single 2p(3/2) core hole, with the Cu 3d band completely filled. On the contrary, in Cu2O the intermediate state is represented by the combination of a 2p(3/2) hole with a 4sp electron in strong interaction with the O-2sp valence band. In CuO, for photon energies higher than 1.5 eV above the L-3-edge maximum, the constant binding energy radiationless Raman peaks are accompanied by constant kinetic energy replicas. These are attributed to the relaxation of the Auger intermediate state through electron-hole pair generation across the band gap of the material. Satellites that could be associated to relaxation precesses involving energies smaller than the band gap are not resolved. No variation of the lineshape of the Anger peaks is observed as a function of the sample temperature, indicating that different densities of thermally accessible excitations do not have a strong influence on the recombination process of the core hole.
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| 5. |
- Green, DR, et al.
(författare)
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Ten years of publication in cell death
- 2004
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Ingår i: Cell death and differentiation. - : Springer Science and Business Media LLC. - 1350-9047 .- 1476-5403. ; 11:1, s. 2-3
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Ohresser, P., et al.
(författare)
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Magnetism of nanostructures studied by x-ray magnetic circular dichroism : Fe on Cu(111)
- 2000
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 62:9, s. 5803-5809
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial growth of Fe on a stepped Cu(111) surface leads to the formation of fee Fe stripes along the step edges for coverages lower than 1.5 monolayer (ML). Using the sensitivity of the x-ray magnetic circular dichroism and sum-rule analysis, the changes in the magnetic properties in the low thickness range from similar to 5% of a monolayer to 4 ML, covering the one-dimensional (1D) coalescence (similar to 0.8 ML) and the 2D percolation limit (similar to 1.5 ML), have been determined. The determination of the spin moment (m(spin)) indicates significant features which can be correlated to the morphological transition. In particular, the m(spin) decreases at the 1D coalescence limit, but increases as the film reaches the 2D percolation limit and starts to transform into the bcc phase. This behavior is tentatively ascribed to the decrease in the Fe atomic volume, as it is well known that such changes can dramatically modify the magnetic properties of gamma-Fe.
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| 7. |
- Tjernberg, Oscar, et al.
(författare)
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Resonant spin resolved photoemission on Ce
- 2000
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 281, s. 723-724
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Tidskriftsartikel (refereegranskat)abstract
- Spin resolved resonant photoemission using circularly polarized light has been performed on thick gamma-Ce films and the measured photoelectrons show a high degree of polarization in agreement with a simple model calculation. The two near Fermi edge features are shown to influence the polarization spectrum in opposite directions, as intuitively expected for states with opposite spin-orbit alignment.
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