Biomedical subjects

O Rader

Publications and source records attributed to O Rader.

At least 19 recordsLinked to original sources

PubMed2005

Probing the ground state electronic structure of a correlated electron system by quantum well states: Ag/Ni(111).

The ground state electronic properties of the strongly correlated transition metal Ni are usually not accessible from the excitation spectra measured in photoelectron spectroscopy. We show that the bottom of the Ni d band along [111] can be probed through the energy dependence of the phase of quantum-well states in Ag/Ni(111). Our model description of the quantum-well energies measured by angle-resolved photoemission determines the bottom of the empty set 1 d band of Ni as 2.6 eV, in full agreement with standard local density theory and at variance with the values of 1.7-1.8 eV from direct angle-resolved photoemission experiments of Ni.

Journal Article↗

PubMed2004

An elastic "sieve" to probe momentum space: Gd chains on W(110).

Electron scattering conditions of one-dimensional nanostructures are explored in angle-resolved photoelectron spectroscopy. Tiny increments of the Gd submonolayer coverage on W(110) lead to strong modifications in the spectra. It is shown that the Gd overlayer represents an elastic superlattice of chains which performs a systematic mapping of the electronic band dispersion of the W substrate through a quasicontinuous series of umklapp wave vectors. Conversely, a single valence-band spectrum contains essential and precise structural information readily accessible by comparison to the band dispersion.

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PubMed2004

Photoemission from stepped W(110): initial or final state effect?

The electronic structure of the (110)-oriented terraces of stepped W(331) and W(551) is compared to the one of flat W(110) using angle-resolved photoemission. We identify a surface-localized state which develops perpendicular to the steps into a repeated band structure with the periodicity of the step superlattices. It is shown that a final-state diffraction process rather than an initial-state superlattice effect is the origin of the observed behavior and why it does not affect the entire band structure.

Journal Article↗

PubMed2003

Electronic structure of carbon nanostripes.

Carbon nanostripes of graphene structure prepared on the stepped Ni(771) surface have been studied by angle-resolved photoemission. The electronic structure is anisotropic: parallel to the stripe direction, a graphite-type dispersion is measured, whereas the perpendicular direction displays two entangled band structures shifted in energy with respect to each other. These are experimentally identified as the microsurface-centered band structure and its umklapp scattered image caused by the superlattice.

Journal Article↗

PubMed2000

One-dimensional spin-polarized quantum-wire states in Au on Ni(110)

Au chain structures have been prepared on Ni(110). Au6 s,p-derived features in photoemission spectra are identified as quantum-wire states due to their strong dispersion along the chains and absence of dispersion perpendicular to the chains in agreement with our ab initio calculation of the electronic structure. Spin analysis reveals that the states have minority-spin character showing that the confinement of electrons in the chain structure depends on the electron spin.

Journal Article↗

PubMed1996