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We report high resolution angle-scanned photoemission and Fermi surface (FS) mapping experiments on the layered transition-metal dichalcogenide 1T-TaS2 in the quasicommensurate (metallic) and the commensurate (insulating) charge-density-wave (CDW) phase. Instead of a nesting induced partially removed FS in the CDW phase we find a pseudogap over large portions of the FS. This remnant FS exhibits the symmetry of the one-particle normal state FS. Possibly, this Mott localization induced transition represents the underlying instability responsible fur the pseudogapped FS.

Au films, from the submonolayer range up to 11 ML, have been deposited in situ at 300 K. The geometrical structures of these films have been investigated combining full-hemispherical x-ray photoelectron diffraction, low-energy electron diffraction (LEED), low-energy ion-scattering spectroscopy, and scanning tunneling microscopy leading to an intermixed Volmer-Weber growth model. The results demonstrate that below 0.5 ML most Au atoms are buried within the second substrate layer, forming inverted Ag/Au areas on the surface. The ejected Ag atoms and vacancies created during the Au-Ag exchange nucleate into elongated two-dimensional Ag islands and vacancy clusters, respectively, quickly breaking up the surface into smaller terraces. Above about 0.5-ML coverage, the Au-Ag exchange mechanism continues to be active. In addition, due to the reduced mobility of Au atoms deposited on inverted Ag/Au areas, one-dimensional Au stripes as well as elongated three-dimensional (1\ifmmode\times\else\texttimes\fi{}3)-symmetric Au islands are observed already at submonolayer coverages on inverted Ag/Au areas. Only after the deposition of more than 8-ML Au is the Ag substrate completely covered, and missing-row reconstructed terraces extend over regions large enough to yield a well-defined 1\ifmmode\times\else\texttimes\fi{}2 LEED pattern. The growth model is compared to both, published thermodynamic equilibrium predictions and molecular-dynamics simulations, revealing that the Au/Ag(110) growth system is kinetically determined.

A laboratory set-up for ultraviolet (UV) photoelectron spectroscopy combining a high intensity UV source and a toroidal UV monochromator, both being commercially available, is described. The source is modified in order to maximize the solid angle collected by the monochromator. Scanning its exit arm length allows for the optimization of the photon intensity as well as the energy resolution by minimizing the defocus term only. By using several different gases such as He, Ne or H2 one obtains a powerful tool to sample extended regions in k-space. Fermi energy maps are presented for Cu(110) in the photon energy range from 10.2 to 48.3 eV. As a result of the variable photon energy an actual zooming into the well-known Shockley surface state is possible.

The substitution site of Y and Pb in the cuprate-type high temperature superconductor Bi2Sr2Ca1Cu2O8+δ is determined in a very direct and unambiguous way by means of angle-scanned x-ray photoelectron diffraction (XPD). Using XPD as a fingerprinting tool, we conclude that Y occupies the Ca sites and Pb the Bi sites, respectively. Furthermore, low-energy electron diffraction data unequivocally show the presence of the incommensurate lattice modulation which is known for pure Bi2212, but not for sufficiently Pb doped Bi2212. We can, therefore, attribute the reappearance of the modulation directly to the Y doping.

The nitrogen-doped (N-doped), type Ib, synthetic diamond (100) surface was investigated by means of X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Photoelectron emission data from the boron-doped (B-doped) and the N-doped diamond (100) surfaces were compared and permitted the energy band diagrams for these differently terminated surfaces to be drawn. We observed emission from energy levels below the conduction band minimum up to the vacuum level and therefore succeed in evaluating the negative electron affinity (NEA) of the hydrogen-terminated diamond surfaces. Both the hydrogen-terminated N- and B-doped diamond (100) surfaces show NEA values of at least −0.2 and −1.0 eV, respectively, while the hydrogen-free surfaces show positive electron affinity. In contrast to the hydrogen-terminated B-doped (100) surface, UPS measurements on the hydrogen-terminated N-doped (100) surface do not reveal a high intensity NEA peak owing to the strong upward band bending. The high intensity NEA peak of B-doped diamond seems to be due to the downward band bending together with the reduced work function because of hydrogen termination. The work function increases for subsequent hydrogen desorption at higher annealing temperatures with associated loss of NEA. For the N-doped diamond (100) surface the work function behaves similarly but the observation of a NEA peak is absent because of the surface barrier formed by the upward band bending.

Pd clusters formed by physical vapor deposition at room temperature (RT) on highly oriented pyrolytic graphite were investigated by a combination of X-ray photoelectron spectroscopy and diffraction, angle-resolved ultraviolet photoelectron spectroscopy, scanning tunneling microscopy and calculations based on the local density functional theory. Different coverages with nominally 3, 5 and 10 A were studied after deposition at RT and after heat treatment at 600°C. Local ordering exhibiting growth with an fcc(1 1 1) orientation is already observed at the lowest coverage, but with no preferred azimuthal orientation in accordance with the substrate itself. However electronic structure features characteristic for a Pd(1 1 1) single crystal appear only after heat treatment.