We consider fluid flow through a layer of adsorbed homopolymer, which we decompose into an equivalent set of polymeric loops, each tethered to the adsorbing wall and obeying Zimm dynamics. Using a multiple scattering analysis, we obtain an integral equation for the velocity profile. New results are presented for flow profiles in steady and oscillatory weak shear past an adsorbed layer at the theta temperature. Near the wall we find a universal behavior under steady shear for the fluid velocity u(z)∼${\mathit{z}}^{\mathit{y}}$ at height z, with an exponent y≃2.0.

In this paper, we consider the utilization of optical amplifiers with bandwidth Δf≃${10}^{14}$ Hz for use in stochastic cooling. It is shown that quadrupole and dipole wigglers can be used as pickups and kickers, respectively. The proposed method increases the application of the stochastic cooling method beyond the traditional area of proton-antiproton cooling. For example, the method has application to electron-positron cooling as well as potential in muon cooling. The proposed method makes possible the independent choice of damping time and source of excitation of emittance, thereby providing a new direction for the design of low-emittance damping rings.

We describe how general lattice images may be used to measure the variation of the potential in crystalline solids in any projection, with no knowledge of the imaging conditions. This approach is applicable to structurally perfect samples, in which interfacial topography or changes in composition are of interest. We present the first atomic-level topographic map of a Si/${\mathrm{SiO}}_2$ interface in plan view, and the first microscopic compositional map of a Si/GeSi/Si quantum well in cross section.

Atomic resolution scanning tunneling microscopy of Si(100)-(2×1) shows that terrace patterning is possible during etching under tuned conditions of Br fluence and temperature. This patterning reflects the coordinated breaking of dimer bonds with redimerization that produces rows of Si doubly bonded to Br adjacent to Si dimers singly bonded to Br. The concerted desorption of the ${\mathrm{SiBr}}_2$ units yields a missing row pattern.

By neutron spin echo spectroscopy we have investigated the dynamic structure factors for single chain relaxation in polymer melts varying the molecular weight through the transition from unrestricted Rouse motion to entanglement controlled behavior. From an analysis of the structure factors with respect to the different relaxation modes we found that, depending on their spatial extension in relation to the entanglement length, large-scale relaxations are successively suppressed with increasing molecular weight. A comparison with macroscopic diffusion and viscosity data yields excellent internal consistency.

The kinetics during the induction period of polymer crystallization is studied by means of depolarized light scattering measurements. The spinodal decomposition during this period is shown to be caused by orientation fluctuations of polymer segments. Time evolution of these orientation fluctuations can be described by the spinodal decomposition kinetics in terms of transformation from the isotropic to nematic phase proposed by Doi et al.

Transport properties and optical conductivity are calculated for the crystalline approximant AlMn alloy. The number of electrons at the Fermi energy is very small and, based on the band structure, the anomalously small dc conductivity and temperature dependent thermoelectric power are explained. A model calculation for the two-dimensional Penrose lattice with random phason strain shows that it becomes more conductive than the perfect Penrose lattice. We propose the mechanism of the interband transition by phason randomness and inelastic scattering for the origin of the anomalous conductivity in real quasicrystals.

Free carbon clusters with various selected sizes (${\mathrm{C}}_{20}$,${\mathrm{C}}_{60}$,${\mathrm{C}}_{900}$) have been deposited on different substrates to obtain continuous thin films (thickness ∼100 nm). The characterization of nanostructures and electronic structures of the films have been performed using various complementary techniques (atomic force microscopy, transmission electron microscopy, electron energy loss spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy). A memory effect of the free carbon cluster properties permits the synthesis of amorphous diamond or graphite films depending on the deposited incident species (${\mathrm{C}}_{20}$ or ${\mathrm{C}}_{900}$, respectively).

The deposition of individual Ir atoms on an Ir(111) surface with a central iridium cluster on it has been observed in the field ion microscope. Around Ir clusters of both 12 and 59 atoms at T=20 K there is an empty zone, ∼2 nearest-neighbor spacings wide, in which condensed atoms are not found. From quantitative measurements of the distribution of adatoms over the surface it appears that atoms from the vapor striking this region skitter over the surface, even at T∼20 K, and are collected at cluster edges. Atoms from the vapor striking the cluster condense without damage to the cluster.

In-beam Mössbauer spectroscopy is applied to study implanted Fe atoms in the alkali metals Li, Na, and K. From the Mössbauer parameters we infer that the Fe implants take up substitutional as well as interstitial sites. The interstitial Fe experiences a strongly increased s-electron density which is shown to hold quite generally in elemental metals and can be explained by the resulting lattice pressure. It is concluded that recently reported local moment formation in the alkali metals has contributions from both substitutional and interstitial Fe.

It is demonstrated that stability criteria derived using elastic stiffness coefficients which govern stress-strain relations at finite deformation give quantitative predictions of crystal instability, as observed in direct molecular dynamics simulations. With the aid of such analysis we show that instabilities can be triggered in succession; as a consequence, the limit of metastability in the superheating of a defect-free crystal can be predicted.

We report measurements of the hysteretic capillary condensation of helium in the porous material Nuclepore which display a hierarchy of return point memory effects and near congruence of closed internal hysteresis loops. Deviations from predictions based on the Preisach model of independent elementary hysteresis domains, originally developed to understand magnetic phenomena, are observed and are attributed to the appearance of additional domains on draining induced by the internal structure of the porous material. Pore intersections result in weak interactions among the pores which lead to avalanches.

The two-dimensional kinetic roughening of steps on vicinal Si(001) has been analyzed with scanning tunneling microscopy for growth at different rates, doses, and temperatures. Growth exponents for the evolution of the step roughness are extracted. They suggest extremely ineffective relaxation mechanisms for the rough step.

We have investigated the dynamics of the relaxed GaAs(110) surface using an ab initio linear-response approach in the framework of density-functional theory. The relaxation geometry was found by minimizing the total energy with the help of the Hellmann-Feynman forces. In terms of the electronic ground-state properties we have calculated the full phonon dispersion of GaAs(110) along high symmetry lines of the surface Brillouin zone by means of a self-consistent first-order perturbation scheme without any adjustable parameters. Our results are in excellent agreement with all available experimental data.

The lattice Boltzmann (LB) method is used to study the kinetics of domain growth of a binary fluid in a number of geometries modeling two-dimensional porous media. Unlike methods which solve the Cahn-Hilliard equation, the LB method correctly simulates fluid properties, phase segregation, interface dynamics, and wetting. Our results, based on lattice sizes of up to 4096×4096, show little evidence to indicate the breakdown of late stage dynamical scaling, and suggest that confinement of the fluid is the key to the slow kinetics observed. Randomness of the pore structure appears unnecessary.

A numerical renormalization group technique based on Wilson’s momentum shell method is presented for interacting, finite Fermi systems. Results for small fullerene analogs show that the method is quite accurate to moderate values of U, and qualitatively better than other approximation methods. The method has potential applicability far beyond the fullerenes.

We have determined the electronic structure around interstitial Fe impurities in hcp Sc, Y, Ti, and Zr. The self-consistent calculations take lattice relaxation into account and were performed using the recently developed real space linear muffin-tin orbital scheme. This is the first time that such realistic calculations have been performed for isolated interstitial impurities in metals. In agreement with experiments, interstitial Fe was found to be nonmagnetic in these hosts; the calculated isomer shifts on both interstitial and substitutional Fe sites are also in excellent agreement with experiments.

The effect of dissipation on confinement is studied for compact QED. This model is relevant to the recently developed gauge theory of high-${\mathit{T}}_{\mathit{c}}$ superconductors. The global phase diagram of the gauge field is clarified in the parameter space of the coupling constant g, the strength of dissipation γ, and the temperature T. Confinement is drastically suppressed by dissipation, and the deconfining phase appears even in the strong-coupling and zero temperature limit when γ exceeds a critical value. This result supports the spin-charge separation in the resonating-valence-bond state.

The electron emission spectrum resulting from thermal collisions of ${\mathrm{He}}^{\mathrm{*}}$($2^3$S) atoms with ${\mathrm{LaCoO}}_3$ was measured as well as the hν-dependent photoemission spectra. The ${\mathrm{He}}^{\mathrm{*}}$ spectrum shows that the lower-lying Co 3d derived (main) bands are strongly suppressed relative to the O 2p derived bands, reflecting the spatial distribution of the initial Co 3d wave functions. On the other hand, the higher-lying Co 3d derived (satellite) band is anomalously enhanced in the ${\mathrm{He}}^{\mathrm{*}}$ spectrum. These findings are discussed on the basis of the initial and final configuration interactions, using a ${\mathrm{Co}}_2$${\mathrm{O}}_{11}$ cluster.

We study how strong Coulomb correlations affect the phonon-mediated superconductivity. Using the Hubbard model representation of a strongly correlated system, we evaluate the Eliashberg electron-pair correlation function for different values of hole doping concentration, x. The pair interaction is repulsive near half filling (x=0), but it becomes attractive above some critical value of x, making the phonon-mediated superconductivity possible. We also compute the isotope effect coefficient.