Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
A hyper-Rayleigh scattering (HRS) system based on an optical parametric power oscillator is described. The first hyperpolarizability, beta, of Crystal Violet dye was measured at 1450 and 1500 nm. The resonance-free beta value, beta(0), for this octupole was found to be comparable with that of the dipolar dye Disperse…
We present a non-self-consistent density-functional based construction of nonorthogonal tight-binding (TB) matrix elements for B, N, BN, BH, and NH within the framework of the linear combination of atomic orbitals formalism using the local-density approximation. Despite the simplicity of the scheme considering only tw…
Energy-filtered electron imaging is one of the future directions of high-resolution electron microscopy (HREM). In this paper, characteristics and applications of energy-selected HREM are illustrated. Image contrast can be dramatically improved with the use of an energy filter. High-resolution chemical-sensitive imagi…
Single-crystal Ce films of more than 300 \AA{} thickness have been epitaxially grown on W(110). Their interaction with molecular oxygen at room temperature has been studied by angle-resolved photoemission, low-energy electron diffraction, and Auger spectroscopy. As a function of the oxygen exposure, the reaction is fo…
A first-principles calculation to determine the electronic properties of trans-polyacetylene using Hedin's $\mathrm{GW}$ approximation for the self-energy is described. To our knowledge this work is the first application of the $\mathrm{GW}$ method to a quasi-one-dimensional system. The zeroth-order approximation is u…
The theoretical analysis of two different Si wires of size 5\ifmmode\times\else\texttimes\fi{}4 and 3\ifmmode\times\else\texttimes\fi{}4, simulating porous Si, has been performed through the linear-muffin-tin-orbitals method in the atomic sphere approximation. All the atomic core energies were self-consistently comput…
The size dependence of the electron-hole exchange interaction in Si nanocrystals is investigated and the excitonic exchange splitting is predicted to be as large as 300 meV in extremely small Si clusters. The exciton-phonon interaction in Si nanocrystals for acoustic phonon modes is formulated to calculate the Stokes…
The authors report on the first demonstration of optical fibres based on the Ga:La:S system. Core-clad structures have been fabricated by the rod and tube method and pulled into lengths > 200 m. Transmission over the wavelength range 1.0 to 6.5 µm, with fibre loss approaching the absorption and scattering level of…
Local structures around Mn in ${\mathrm{In}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$As films grown by molecular-beam epitaxy have been studied by using Mn K-edge extended x-ray-absorption fine-structure (EXAFS) technique. Substitution of Mn atoms for the In sites is found in samples either gr…
We present electronic transport studies of the aging process in naphtalene--sulfonate-doped polypyrrole. They include in situ conductivity measurements as a function of the aging time up to 1 month, and conductivity and thermoelectric power measurements in the temperature range 300--15 K for different aging times at 1…
The relationship between the ion-beam energy and the stress in thin carbon films is studied using two-dimensional molecular-dynamics simulations. In agreement with experiment, a transition is seen from tensile to compressive stress with increasing ion energy. The compressive stress reaches a maximum near 30 eV, after…
We have analysed the expression of five protein kinase C [PKC] isoforms in an in vitro model using nontumorigenic rat colonic epithelial cells FRC/TEX CL D [D/WT] and in the related tumorigenic Ha-ras-transformed FRC/TEX CL D/H-ras line [D/ras]. The PKC subspecies alpha, delta, epsilon and xi were expressed at the pro…
We have developed, in the framework of a broken-bond model, a method to determine the surface composition of transition metal alloys. The model is based on the equivalent-medium approximation which allows us to calculate the energies of surface layers as a function of local concentration. The model also considers bond…
Trimanganese(II) dipotassium bis(hydroxide) bis(tetraoxovanadate), K2Mn3(OH)2(VO4)2, has a layered structure. The [Mn3(OH)2(VO4)2]n2n- layers comprise CdI2-like planes of MnO4(OH)2 octahedra with 1/4 Mn vacancies, to which VO4 tetrahedra are linked on both sides via three vertices; the fourth vertex points into the in…
A general scheme for the spin adaptation of open-shell coupled-cluster theory is presented, and the generalization to genuine multireference cases is briefly discussed. In our formulation the wave operator is parameterized such that it automatically commutes with the spin operators, and the correlated wave function is…
We describe by approximate MO calculation a number of species for which high spin states are either the ground state or lie very low in energy. These are models for the spin coupling in projected ferromagnetic organic materials. The theory guiding their construction is based on planar conjugated systems, while experim…
A range of $〈110〉$ symmetric tilt grain boundaries (GB's) are investigated in several fcc metals with simulations and high-resolution electron microscopy. Boundaries with tilt angles between 50.5\ifmmode^\circ\else\textdegree\fi{} and 109.5\ifmmode^\circ\else\textdegree\fi{} dissociate into two boundaries 0.6 to 1.1 n…
The results of first-principles calculations of the electronic band structures, equilibrium lattice constants, cohesive energies, bulk moduli, and magnetic moments are presented for the rare-earth pnictides with the rocksalt structure and chemical formula R-V, where R=Gd, Er, and the group-V elements N, P, and As. The…
In the context of perovskite quantum paraelectrics, we study the effects of a quadrupolar interaction $J_q$, in addition to the standard dipolar one $J_d$. We concentrate here on the nonlinear dielectric response $χ_{P}^{(3)}$, as the main response function sensitive to quadrupolar (in our case antiquadrupolar) intera…
Motivated by the negative thermal expansion observed for silicon between 20 K and 120 K, we present an ab initio study of the volume dependence of interatomic force constants, phonon frequencies of transverse-acoustic TA(X) and TA(L) modes, and of the associated mode Gr\"uneisen parameters. The influence of successive…