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In two different treatments of the Nuzi contract HSS V 67, E. A. Speiser provided two different transliterations and translations of a key phrase without giving his reasons for the revision. It turns out that the text in question is damaged, rendering one particular cuneiform sign nearly unreadable. The significance of Speiser's revision for biblical studies is that, depending on which reading is taken, this text provides some legal background either for the concern that a full wife might send away the children of a secondary wife (as in Gen 21) or for the phenomenon of surrogate motherhood (i.e., the identification of the child of a secondary wife as in some way the child of the full wife; see Gen 16 and 30). Though some biblical scholars have noted Speiser's two translations, no one sofar has engaged in a technical discussion of the primary text in order to understand the revision. Rather, scholars have sometimes simply chosen the reading that fits better with their purposes (usually Speiser's earlier reading). This article examines the original cuneiform text of HSS V 67 in order to ascertain, using orthographic and linguistic data, which of Speiser's two readings is the more likely. Speiser's revised reading proves to be the correct one, meaning that HSS V 67 does not provide a legal background for the concern that a full wife might send away the sons of a secondary wife (e.g., Gen 21). [ABSTRACT FROM AUTHOR]

High-resolution Raman spectroscopy at low frequencies (<100cm-1) is used to reinvestigate and identify the surface phonons localized in the first atomic layers of In:Si(111)(4?1) and (8?2). The frequency and symmetry of low-energy surface phonons are strongly related to surface structure. The measured phonons are assigned to characteristic modes of the quasi-one-dimensional indium nanowires on Si(111) by means of density-functional theory calculations and symmetry considerations. It is found that the low-temperature (8?2) and the room-temperature (4?1) phases of the In:Si(111) surface are characterized by distinct sets of phonon modes. Strong modifications in Raman spectra upon the phase transition are, on the one hand, related to backfolding induced by symmetric quadruplication of the surface unit cell and, on the other hand, to structural changes within the surface unit cell. These are indications for two distinct structural phases, supporting the first-order transition scenario. The characteristic structural changes are thus verified in detail. [ABSTRACT FROM AUTHOR]

Rare earth metals are known to interact strongly with Si(001) surfaces to form different types of silicide nanostructures. Using STM to structurally characterize Dy and Tb silicide nanostructures on vicinal Si(001), it will be shown that reflectance anisotropy spectroscopy (RAS) can be used as an optical fingerprint technique to clearly distinguish between the formation of a semiconducting two-dimensional wetting layer and the metallic one-dimensional nanowires. Moreover, the distinctive spectral features can be related to structural units of the nanostructures. RAS spectra of Tb and Dy nanostructures are found to show similar features. [ABSTRACT FROM AUTHOR]

The grating of self-assembled Si nanoribbons at the Ag(110) surface has been studied by Raman spectroscopy. The study, conducted in situ with uncapped samples, resulted in phonon frequencies in disagreement with the results of theoretical calculations reported in literature for freestanding silicene sheets and nanoribbons. These results suggest that the structure of these silicon nanoribbons is very different from the planar and lightly buckled structural models and that the influence of the substrate might be underestimated in the discussed structural models. [ABSTRACT FROM AUTHOR]

We propose a quantitative and reversible method for tuning the charge localization of Au-stabilized stepped Si surfaces by site-specific hydrogenation. This is demonstrated for Si(553)-Au as a model system by combining density functional theory simulations and reflectance anisotropy spectroscopy experiments. We find that controlled H passivation is a two-step process: step-edge adsorption drives excess charge into the conducting metal chain "reservoir" and renders it insulating, while surplus H recovers metallic behavior. Our approach illustrates a route towards microscopic manipulation of the local surface charge distribution and establishes a reversible switch of site-specific chemical reactivity and magnetic properties on vicinal surfaces. [ABSTRACT FROM AUTHOR]

Abstract: The morphology, structure and phonon properties of well-aligned and kink-free GaAs nanowires grown on (1¯1¯1¯)B GaAs are reported. The nanowires were grown at temperatures down to 400°C by Au-catalysed MOVPE using tBuAsH2 and Me3Ga in H2 ambient. Colloidal Au nanoparticles (NPs) with average size of 60–70nm were used as catalyst. Below 425°C the nanowires consist of almost cylindrical segments, their average diameter closely matching that of the original Au NPs. At higher temperatures, the nanowires show a large tapering. The structural analysis of nanowire samples grown at 450°C evidences that residual catalyst droplets at the nanowire tips consist of crystalline fcc Au, with a preferred (111) crystallographic orientation, and orthorhombic GaAu2 alloy (γ phase). Non-resonant Raman scattering experiments carried out on GaAs nanowires showed no evidence of phonon confinement effects. However, new strong LO phonon contributions arise in the Raman spectra with respect to bulk GaAs, likely due to the nanowire large surface-to-volume ratio. [Copyright &y& Elsevier]

Wires having a width of one or two atoms are the smallest possible physical objects that may exhibit one-dimensional properties. In order to be experimentally accessible at finite temperatures, such wires must stabilized by interactions in two and even three dimensions. These interactions modify and partly destroy their one-dimensional properties, but introduce new phenomena of coupling and correlation that entangle both charge and spin. We explore this fascinating field by first giving an overview of the present status of theoretical knowledge on 1D physics, including coupling between chains and to the substrate, before we set out for experimental results on ordered arrays of atomic wires on both flat and vicinal Si(111) surfaces comprising Si(111)-In, Si(hhk)-Au, Si(557)-Pb, Si(557)-Ag, on Ge(001)-Au and of rare earth silicide wires. While for these systems structural, spectroscopic and (magneto-)conductive properties are in the focus, including temperature- and concentration-induced phase transitions, explicit dynamics on the femto- and picosecond time scales were explored for the modified Peierls transition in indium chains on Si(111). All these systems are characterized by strong correlations, including spin, that are extended over whole terraces and partly beyond, so that small geometric changes lead to large modifications of their electronic properties. Thus this coupling in one (1D), two (2D) (and even three) dimensions results in a wealth of phase transitions and transient quasi-1D conductance. As extremes, modified quasi-1D properties survive, as in the Si(111)-In system, whereas strong Fermi nesting results in entanglement of spin and charge between terraces for Si(557)-Pb, so that spin orbit density waves across the steps are formed. [ABSTRACT FROM AUTHOR]

Density-functional-theory calculations are combined with many-body perturbation theory in order to elucidate the geometry, electronic, and optical properties of the uiz-GaN(lIOO) surface, i.e., the so-called m-plane. The optical absorption and reflection anisotropy related to electronic transitions between surface states are identified by comparison with measured data covering transition energies from 2.4 up to 5.4 eV. Our results show a surface relaxation mechanism consistent with the electron counting rule that causes a moderate buckling of the GaN surface dimers and gives rise to two distinct surface states: The doubly occupied N dangling bonds form a surface band that is resonant with the GaN valence-band edge at the center of the Brillouin zone, whereas the empty Ga dangling bonds occur within the GaN band gap closely following the dispersion of the conduction-band edge. These two states contribute strongly to the formation of surface excitons that redshift the optical absorption with respect to the bulk optical response. The surface optical absorption i.e., the excitonic onset below the bulk band gap followed by a broad absorption band at higher energies related to the dispersion of the surface band structure, is calculated in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The electronic structure of GaN(1-100) surfaces is investigated in-situ by photoelectron spectroscopy (PES) and reflection anisotropy spectroscopy (RAS). Occupied surface states 3.1 eV below the Fermi energy are observed by PES, accompanied by surface optical transitions found in RAS around 3.3 eV, i.e., below the bulk band gap. These results indicate that the GaN(1-100) surface band gap is smaller than the bulk one due to the existence of intra-gap states, in agreement with density functional theory calculations. Furthermore, the experiments demonstrate that RAS can be applied for optical surface studies of anisotropic crystals. [ABSTRACT FROM AUTHOR]

We have studied the surface phonon modes of the reconstructed Si(111)-(7×7) surface by polarized Raman spectroscopy. Six surface vibration modes are observed in the frequency range between 62.5 and 420.0 cm-1. The mode frequencies agree very well with reported calculation results. This enables their attribution to calculated eigenmodes, whose elongation patterns are dominated by specific atomic sites: the two most characteristic novel fingerprints of the (7×7) reconstruction are sharp Raman peaks from localized adatom vibrations, located at 250.9 cm-1, and collective vibrations of the adatoms and first- and second-layer atoms, located at 420.0 cm-1. While the sharp localized adatom vibration peak is a substantial refinement of an earlier broad spectral structure from electron energy-loss spectroscopy, no spectroscopic features were reported before in the collective-vibration frequency region. Furthermore, we observe in-plane wagging vibrations in the range from 110 to 140 cm-1, and finally the backfolded acoustic Rayleigh wave at 62.5 cm-1, which coincides with helium atom scattering data. Moreover, the Raman peak intensities of the surface phonons show a mode-specific dependence on the polarization directions of incident and scattered light. From this polarization dependence the relevant symmetry components in the Raman scattering process (A i and/or E symmetry) are deduced for each mode. [ABSTRACT FROM AUTHOR]

Abstract: Multiwall carbon nanotubes are found to generate photocurrent in the visible and near ultra violet spectral range using a photoelectrochemical technique. Peaks in the photocurrent are observed at excitation energies in the visible region. Their electron energy loss spectra exhibit the π plasmon feature, typical of graphite layers, and a peak at lower energy. Features at energies between 0 and 4eV have been already observed for single wall carbon nanotubes and ascribed to interband electronic transitions due to the reduced dimensionality of these systems. The present measurements suggest that the usual identification of multiwall carbon nanotubes electronic density of states with that of graphite layers is not sufficient and more theoretical investigations are necessary to shed light on this point. [Copyright &y& Elsevier]

We report photocurrent generation in entangled networks of multiwall-carbon nanotubes (MWCNTs) grown on TiN/Si substrates by an all-laser process. By integrating these MWCNTs into planar devices, we demonstrate that they generate photocurrent over all the visible and near-ultraviolet range, with maximum efficiency around 420 nm. Photocurrent is obtained even at zero applied voltage, pointing to a true photovoltaic (PV) effect. The extracted photocurrent as a function of applied voltage exhibits nonlinear behavior for voltages ≥2 V, suggesting that the devices do not behave as pure photoresistances. Other mechanisms (e.g., Schottky barriers imbalance) are invoked to describe current flow in these PV devices. [ABSTRACT FROM AUTHOR]

Density-functional theory is used to explore the Si(553)-Au surface dynamics. Our study (i) reveals a complex two-stage order-disorder phase transition where with rising temperature first the ×3 order along the Si step edges and, subsequently, the ×2 order of the Au chains is lost, (ii) identifies the transient modification of the electron chemical potential during soft Au chain vibrations as instrumental for disorder at the step edge, and (iii) shows that the transition leads to a self-doping of the Si dangling-bond wire at the step edge. The calculations are corroborated by Raman measurements of surface phonon modes and explain previous electron diffraction, scanning tunneling microscopy, and surface transport data. [ABSTRACT FROM AUTHOR]

The authors demonstrate the ability of multiwall carbon nanotubes to generate photocurrents in the near ultraviolet and visible spectral ranges using electrochemical photocurrent measurements. The photogenerated current depends on the excitation wavelength similar to that for single wall carbon nanotubes. Its intensity and modulation can be related to the carbon nanotubes morphology. The maximum photon-to-current conversion efficiency is approximately 7%, about 50 times higher than that reported for single wall carbon nanotubes. This result is of particular relevance for photovoltaic nanodevices and solar energy conversion applications. [ABSTRACT FROM AUTHOR]

The vibrational properties of the Au-induced (√3x √3)R 30° reconstruction of the Si(111) surface are investigated by polarized surface Raman spectroscopy and density-functional theory. The Raman measurements are performed in situ at room temperature as well as 20 K, and they reveal the presence of vibrational eigenmodes in the spectral range from 20 to 450 cm-1. In particular, two peaks of E symmetry at 75 and 183 cm-1 dominate the spectra. No substantial difference between room- and low-temperature spectra is observed, suggesting that the system does not undergo a phase transition down to 20 K. First-principles calculations are performed based on the structural models discussed in the literature. The thermodynamically stable conjugate honeycomb-chained-trimer model (CHCT) [Surf. Sci. 275, L691 (1992)] leads to phonon eigenvalues compatible with the experimental observations in the investigated spectral range. On the basis of the phonon eigenfrequencies, symmetries, and Raman intensities, we assign the measured spectral features to the calculated phonon modes. The good agreement between measured and calculated modes provides a strong argument in favor of the CHCT model. [ABSTRACT FROM AUTHOR]

Ordered submonolayers of adsorbate atoms on semiconductor surfaces constitute a playground for electronic correlation effects, which are tightly connected to the local atomic arrangement and the corresponding vibration eigenmodes. We report on a study of the vibration eigenmodes of Au-covered Si(111) surfaces with (5 × 2) reconstruction using polarized Raman spectroscopy and first-principles calculations. Upon Au coverage, the vibration eigenmodes of the clean reconstructed Si(111)- (7 × 7) surface are quenched and replaced by new eigenmodes, determined by the Au- (5 × 2) reconstruction. Several polarization-dependent surface eigenmodes emerge in the spectral range from 25 to 120 cm-1, with the strongest ones at 29, 51, and 106 cm-1. In our first-principles calculations we have determined the vibration frequencies, the corresponding elongation patterns, and the Raman intensities for two different structure models currently discussed in the literature. The best agreement with the experimental results is achieved for a model with 0.7 monolayer coverage and seven Au atoms per unit cell, proposed by S. G. Kwon and M. H. Kang [Phys. Rev. Lett. 113, 086101 (2014)]. [ABSTRACT FROM AUTHOR]