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Angle dependent X-ray emission spectroscopy (AXES) is introduced as a tool for depth dependent composition analysis. A controlled variation of the information depth is demonstrated by changing the geometry from grazing exit to grazing incidence geometry. First results are presented from Cu(In,Ga)Se 2 (CIGSe)-based polycrystalline thin film solar cell bi-layer components. A mathematical model explains changes in relative intensity due to the absorption and emission behavior of thin CdS and Zn(S,O) cover layers. The fact that the presented data can be modelled by ideal bi-layer structures, provides both, proof of concept in general and the proof of applicability to the relatively rough layered structures based on CIGSe. In bare CIGSe a homogeneous distribution of Cu and Ga is found in a depth range between 22 and 470 nm.

We investigated energy-transfer processes in a bridged organic donor–acceptor dyad system of triphenyldiamine and perylenebisimide using time-resolved and fluorescence emission spectroscopy. The fluorescence lifetimes of the isolated model components and their mixtures have been determined as a function of the concentration of the chromophores. Subsequently, energy-transfer experiments were conducted in solutions of free donors, free acceptors and their mixtures. The results of these experiments are in reasonable agreement with predictions based on Forster theory. Finally, experiments were performed on a donor–acceptor system covalently bound by a C12H24-linker.

Rayleigh-B\'{e}nard convection in horizontal layers of binary fluid mixtures heated from below with realistic horizontal boundary conditions is studied theoretically using multi-mode Galerkin expansions. For positive separation ratios the main difference between the mixtures and pure fluids lies in the existence of stable three dimensional patterns near onset in a wide range of the parameter space. We evaluated the stationary solutions of roll, crossroll, and square convection and we determined the location of the stability boundaries for many parameter combinations thereby obtaining the Busse balloon for roll and square patterns., Comment: 19 pages + 15 figures, accepted by Journal of Fluid Mechanics

using photoemission and electron energy-loss spectroscopy in transmission. In particular, the impact of the isomer symmetry of the C82 cage (Cs or C3v) on the electronic structure and on the optical properties is analysed in detail. For both isomers, combined XPS and XAS measurements of the Tm 4f and 4d states offer conclusive proof of a divalent encaged Tm ion. No significant change of the valence of the rare earth ion upon changes in the cage symmetry is observed. From the C 1s excitation spectra we find a more pronounced LUMO for the C3v(8) isomer, as is expected for the higher symmetry of the cage. Additional information about the optical properties was obtained from the low-energy loss function. With use of a Kramers–Kronig analysis, the dielectric function, e, and the optical conductivity, σ, have been derived. e(0) and the onset of the spectral weight are found to be 7.7 [12.8] and 0.6 eV [0.8 eV] for the Cs(6) {C3v(8)} isomer, respectively.

Results of local density first principles LCAO calculations for a 13 layer slab of free and modified As-terminated (1 × 1) GaAs(001) surfaces are presented. The surfaces are covered by a monolayer of hydrogen, copper, or ruthenium. The surface calculation for the hydrogen covered surface gives hydrogen-induced and GaAs surface states in agreement with angle-resolved photoemission results within the energy range where they are found. For the systems GaAs(001):Cu and GaAs(001): Ru metal induced gap states are predicted with a density of 2 × 1015 cm−2. The calculated surface states indicate a higher Schottky barrier for the ruthenium than for the copper covered surface. Ergebnisse nichtempirischer LCAO-Berechnungen auf lokaler Dichtenaherung fur die Elektronenstruktur freier und modifizierter (1 × 1) GaAs(001)-Oberflachen werden vorgestellt. Die Oberflachen werden durch 13 Atomlagen dicke Slabs modelliert und sind mit einer kompletten Monolage Wasserstoff, Kupfer bzw. Ruthenium bedeckt. Fur die mit Wasserstoff bedeckte GaAs(001)-Oberflache stimmen die Ergebnisse gut mit experimentellen, aus winkelaufgeloster Photoemission stammenden Befunden uberein. Fur die Systeme GaAs(001): Cu und GaAs(001): Ru werden durch das Metall induzierte Gap-Zustande mit einer integrierten Zustandsdichte von 2 × 1015 cm−2 erhalten. Die energetische Lage der berechneten Oberflachenzustande erklaren die hohere Schottkybarriere der Ru-bedeckten Oberflache gegenuber der Cu-bedeckten.

Polar (100) surfaces of commercial CdTe and Cd(Zn)Te single crystals were prepared by ion sputtering and annealing at different temperatures and under Te flux, Cd flux, or in ultrahigh vacuum. Various surface reconstructions with high structural order were obtained. Soft x-ray photoemission investigations of the Cd and Te 3d surface core-level shifts were employed to derive the surface termination, revealing Cd-terminated surfaces for most preparations and various reconstructions. The results suggest that sputter/annealing cycles are suitable for the preparation of highly ordered and uniformly terminated substrates for semiconductor heterojunctions on CdTe and Cd(Zn)Te without the need of an additional buffer layer.

Hereditary non-polyposis colorectal cancer (HNPCC) is a common hereditary syndrome characterized by the high incidence and early onset of colorectal cancer. The majority of the HNPCC families carry germline mutations in either the MSH2 or the MLH1 mismatch repair gene. A 46 year-old female patient whose family history fulfilled the Amsterdam criteria for HNPCC was diagnosed with undifferentiated adenocarcinoma of the transverse colon. Recognizing the Lynch 2 syndrome (the existance of multiple HNPCC related cancers in a pedigree), we used polymerase chain reaction followed by direct sequencing to screen the coding regions of both the MSH2 and the MLH1 genes for germline mutations in DNA from the patient. We detected a novel germline mutation (300-305delAGTTGA) in exon 2 of human MSH2. We noted microsatellite instability in four microsatellite loci. Immunohistochemistry showed a lack of expression of the MSH2 gene product in the tumor, suggesting that the mutation is a disease-causing mutation.

The connection between resonances occuring in the scattering of electrons on atoms (molecules) with or without the presence of a classical laser field is demonstrated for aN-state model-atom in 1st order perturbation theory with respect to the laser field. It is possible to predict the position, the shape and the background of resonances in the laser field from the sole knowledge of the corresponding scattering amplitudes without the laser field. At first, a soft-photon approximation for individual partial wave amplitudes is derived. This approximations is then tested numerically for a 2-state square well potential model. Details about the accuracy of the soft-photon approximation are obtained by comparing with the numerically exact results. Finally our findings are applied to give an interpretation of recent experimental data.

Moglichkeiten der quantenchemischen Berechnung thermodynamischer Gleichgewichtsdaten fur die Elektronentransferlumineszenz- bzw. Elektronentransferloschreaktionen zwischen aromatischen π-Elektronensystemen in Losung werden diskutiert und derartige Berechnungen fur einige Systeme durchgefuhrt. Die kleine Enthalpie dieser Reaktionen ergibt sich als Summe der wesentlich groseren negativen Enthalpie einer hypothetischen Gasphasenreaktion und positiven Anderung der Solvatationsenthalpie. Ferner wird die Moglichkeit untersucht, durch LFE-Beziehungen die Freie Reaktionsenthalpie aus quantenchemisch berechneten Grosen vorauszusagen. Es zeigt sich, das dies nur in kleinen Gruppen verwandter Substanzen moglich ist.

The optical constants of nickel are found to vary with temperature. Most of the temperature dependence is carried by a Drude‐like term, with a temperature dependent relaxation time τ−1(T) =τ−10+bT2. The interband absorption itself has an anomalous behaviour in that it first increases with T, then over ΔT?100° around TC, falls down rapidly by same amount. The interband polarization e1 shows a small singularity at TC. There is presently no straightforward explanation for these phenomena. Structures in the interband absorption spectrum, above 0.8 eV, are found to correlate well with a recent photoemission deduced band model, and particularly confirm the smaller (∼3.5 eV) width of the d band. Simultaneously a value of 0.1 eV for the spin‐orbit parameter, and an estimate (0.4 eV) for the exchange splitting of L31, are obtained.