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。
Biexcitons localized in ultrathin CdS/ZnS single quantum wells with fluctuating well thicknesses are investigated by two-photon absorption and single-exciton spectroscopy. For the binding energy of the confined biexciton, a value of $\ensuremath{\Delta}{E}_{\mathrm{B}}=38$ meV is determined. Comparing $\ensuremath{\De…
The local structure around Al and P impurities in silica is investigated using density-functional theory. Two distinct cases are considered: impurities substituting for a Si atom in $\ensuremath{\alpha}$ quartz, and impurities implanted in a stoichiometric $\ensuremath{\alpha}$-quartz crystal. Both impurity elements a…
The catalytically active copper phase for the partial oxidation of methanol is studied by means of time-resolved extended X-ray absorption fine structure (EXAFS) spectroscopy combined with the detection of the catalytic turnover. It is found that the active form of the copper is a strained nanocrystalline form of the…
Elastic methods are presently being used to study the space charge distributions in insulators. They are limited in their interpretation to simple geometries whereas real systems often involve complex structures such as the case for divergent electric field regions. The authors propose a general theory for the interpr…
We show that a cylindrical quantum wire whose lateral surface is deformed may support surface states localized on the deformation. This surface localization can be studied upon writing the single-particle Schr\"odinger equation in a curvilinear coordinates system on the surface. The energies of these localized states…
“Observation of d orbital holes.” “Electrons seen in orbit.” These headlines were for two articles in Nature on the electronic structure of Cu2O. The stirring statements on X-ray electron-density determinations, on bonds, and on the existence and shape of orbitals are challenged herein with respect to six points, on t…
Ein ausgedehntes konjugiertes π-System und einstellbare optische Eigenschaften weisen Verbindungen mit einem linearen Rückgrat aus Elektronendonor-Thiophen- und Elektronenacceptor-Pyridineinheiten sowie einem σ3,λ3-Phospholgerüst auf. Die gemischten Oligomere 1 und 2 sind hochkonjugierte fluoreszierende Chromophore. D…
Implantation-induced, microstructural modifications including increased bond length and non-Gaussian static disorder have been measured in amorphous Ge using extended x-ray absorption fine-structure spectroscopy. The evolution of the amorphous phase interatomic distance distribution as functions of ion dose and implan…
We report electrical transport measurements of synthetic diamonds doped with boron about 100 ppm. The resistivity has been measured in the temperature range 20--300 K by the van der Pauw method. We have also investigated infrared absorption coefficient at room temperature. Furthermore, we have studied the effect of ${…
We have measured the valence-band discontinuity at artificially structured, epitaxial heterojunctions of $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Cr}}_{2}{\mathrm{O}}_{3}(0001)$ and $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}(0001).$ Layered film structures of these two materials maintain the…
The very stable selenium-bridged gold complexes [Au10Se4(dppm)4]Br2 and [Au18Se8(dppe)6]Cl2 were obtained by the reaction of gold halide–phosphane complexes [(AuX)2(Ph2P(CH2)nPPh2)] (X=halide; n=1, 2) with silylated selenium derivatives. With the help of electrospray/ionization it was possible to promote the cation [A…
We investigate the electronic and atomic structure of interstitial hydrogen impurities in PbTiO3 and investigate their effect on ferroelectric polarization through first-principles total-energy calculations. Interstitial H in PbTiO3 is found to bond to oxygen and to act as a shallow donor impurity. At equilibrium, H d…
The electronic structure of lightly Nb-doped ${\mathrm{SrTiO}}_{3}$ has been investigated using high resolution x-ray absorption spectroscopy (XAS). Below the O $1s$ threshold, XAS spectra show two features due to empty states whose energy positions match with those of the $3d$ photoemission spectra in the band gap en…
The study of inelastic scattering of electrons moving in a surface region is important to a comprehensive understanding of the basic process of electron-surface interaction in a surface electron spectroscopy. A numerical formalism was previously developed to calculate the complex electron self-energy near a metal surf…
It is known that when irradiating a graphite surface with ions the predominant source of defects are vacancies. Vacancies are also formed in a growing graphite sheet and cannot be filled. The theoretical work that has been carried out so far on the properties of these defects has only involved quite small model system…
We have studied the strain effects on the structural and magnetotransport properties of Pr0.67Sr0.33MnO3 (PSMO) thin films. The PSMO films were epitaxially grown on LaAlO3 (001), SrTiO3 (001), and NdGaO3 (110) substrates that induce biaxial compressive, tensile, and almost no strain in the films, respectively. The fil…
We report an optical microscopy study on the domain structures of 0.955Pb(Zn1/3Nb2/3)O3–0.045PbTiO3 rhombohedral phase single crystals poled along [001] of the cubic coordinates. Both charged and uncharged domain walls are observed in domain engineered samples and they could join together to form “L” and “T” shaped do…
Escherichia coli hosts expressing fabG of Pseudomonas aeruginosa showed 3-ketoacyl coenzyme A (CoA) reductase activity toward R-3-hydroxyoctanoyl-CoA. Furthermore, E. coli recombinants carrying the poly-3-hydroxyalkanoate (PHA) polymerase-encoding gene phaC in addition to fabG accumulated medium-chain-length PHAs (mcl…
We use the instantaneous normal mode approach to provide a description of the local curvature of the potential energy surface of a model for water. We focus on the region of the phase diagram in which the dynamics may be described by mode-coupling theory. We find that the diffusion constant depends on the fraction of…
We have investigated theoretically the STM images and conductance signatures of defective carbon nanotubes. The defects considered are those that form on nanotubes under tension, both in the absence and presence of additional carbon atoms. The most prominent features observed in the STM images are a set of bright ring…