Angle resolved photoemission from a 001 surface of single crystal Ni23Cu77 random substitutional alloy

We have studied the angular distribution of photo-emitted electrons from a 001 surface of single crystal Cu₇₇Ni₂₃ random substitutional alloy. A number of alloying effects were observed. We have interpreted these in terms of calculations based on the Coherent Potential Approximation for non-overlapping muffin tin potentials (KKR-CPA).     

An XPS investigation of the electronic structure in AgZn

We have calculated the densities of states in ordered (CsCl) and disordered (bcc) AgZn using first-principles SCF-LMTO-ASA and KKRCPA techniques. We obtain good agreement between calculated XPS photocurrent spectra and experimental measurements in the valence band region. As far as we can determine there are no shifts of the Ag nor Zn core levels on alloying.     

Observed Ds(2317) and tentative D(2100-2300) as the charmed cousins of the light scalar nonet

The very recently observed D(*)(sJ)(2317)(+) meson is described as a quasibound scalar csmacr; state in a unitarized meson model, owing its existence to the strong 3P0 Okubo-Zweig-Iizuka-allowed coupling to the nearby S-wave DK threshold. By the same mechanism, a scalar D(*)(0)(2100-2300) resonance is predicted above the Dpi threshold. These scalars are the charmed cousins of the light scalar nonet f(0)(600), f(0)(980), K(*)(0)(800), and a(0)(980), reproduced by the same model. The standard cnmacr; and csmacr; charmed scalars D0 and D(s0), cousins of the scalar nonet f(0)(1370), f(0)(1500), K(*)(0)(1430), and a(0)(1450), are predicted to lie at about 2.64 and 2.79 GeV, respectively, both with a width of some 200 MeV.     

Study of Interfacial Film Growth with ac Measurements

The relevance of ac measurements for the study of developing films at solid-liquid interfaces is discussed. An electrical model is introduced, and the correspondence of each circuit element with a chemical or physical process is explained. Further details are discussed mostly by considering the spontaneous development of a solid film at a Zn|CrO(3)(aq) interface. It is shown that less straightforward ac behavior may be understood after modification of the general electrical model, based on supplementary information on the studied system. For the experimental system considered, the most important film growth characteristics are derived. Copyright 2000 Academic Press.     

Electrochemical study of the oxidation of tin(II) at glassy carbon electrodes

The voltammetric characteristics of the Sn(IV)/Sn(II) system have been studied at a glassy carbon rotating disk electrode in 4M hydrochloric acid. Anodic oxidation of Sn(II) produces a single well-defined wave, which has been examined in the temperature range 20-50 degrees , and shows distinct irreversibility. The kinetic parameters of the oxidation reaction have been calculated. Kinetic features of the reduction of Sn(IV) to Sn(II) were not evaluated because the reduction proceeds directly to tin metal.     

Multichannel calculation of D*s vector states and the D+sJ(2632) resonance

We study bound states below threshold and resonances above threshold in the D0K+ and D(+)(s)eta systems, using a many-coupled-channel model for nonexotic meson-meson scattering applied to states with the quantum numbers of cs quark-antiquark vector mesons. We fit the ground state at 2.112 GeV, whence the lowest resonances in D0K+ come out at 2.61, 2.72, 3.03, and 3.08 GeV. The resonance at 2.61 GeV acquires a width of about 8 MeV, while its partial P wave cross section is up to 6 times larger in D(s)eta than in D0K+, provided a mechanism accounting for Okubo-Zweig-Iizuka-forbidden decays is included. The latter finding is in agreement with the observations of the SELEX Collaboration with respect to the recently reported D(+)(sJ)(2632) resonance. Therefore, we conclude that the D(+)(sJ)(2632) is probably the first recurrence of the D(*)(s)(2112) meson.     

Investigation of Anisotropy-Resolving Turbulence Models by Reference to Highly-Resolved LES Data for Separated Flow

The predictive properties of several non-linear eddy-viscosity models are investigated by reference to highly-resolved LES data obtained by the authors for an internal flow featuring massive separation from a curved surface. The test geometry is a periodic segment of a channel constricted by two-dimensional (2D) `hills' on the lower wall. The mean-flow Reynolds number is 21560. Periodic boundary conditions are applied in the streamwise and spanwise directions. This makes the statistical properties of the simulated flow genuinely 2D and independent from boundary conditions, except at the walls. The simulation was performed on a high-quality, 5M-node grid. The focus of the study is on the exploitation of the LES data for the mean-flow, Reynolds stresses and macro-length-scale. Model solutions are first compared with the LES data, and selected models are then subjected to a-priori studies designed to elucidate the role of specific model fragments in the non-linear stress-strain/vorticity relation and their contribution to observed defects in the mean-flow and turbulence fields. The role of the equation governing the length-scale, via different surrogate variables, is also investigated. It is shown that, while most non-linear models overestimate the separation region, due mainly to model defects that result in insufficient shear stress in the separated shear layer, model forms can be derived which provide a satisfactory representation of the flow. One such model is identified. This combines a particular quadratic constitutive relation with a wall-anisotropy term, a high-normal-strain correction and a new form of the equation for the specific dissipation ω = ∈/k. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evidence for further charmonium vector resonances

We discuss the shape of threshold signals in production cross sections of the reaction e<'+>e<,-> → D<'*>D<'*>, at the opening of the D<,s><'*>D<,s><'*> and Λ<,c><'+>Λ<,c><'-> channels. Furthermore, evidence for the ψ(3D), ψ(5S), ψ(4D), ψ(6S), ψ(5D), ψ(7S), ψ(6D), and ψ(8S) new charmonium vector resonances is presented, on the basis of data recently published by the BABAR Collaboration. Central masses and resonance widths are estimated. Confirmation of these resonances would be a huge step in lifting the precision level of hadron spectroscopy towards that of atomic spectroscopy, with far-reaching consequences for theory.