Materials Literature
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Faraday effect measurements have been carried out at room temperature for some sodium borate glasses containing Eu2+ ions prepared under a reducing atmosphere. The wavelength dependence of the Verdet constant is analyzed in terms of a theory derived by Van Vleck and Hebb to obtain effective transition wavelength of th…
The chemical state of sulfur on (NH${}_{4}{)}_{2}{\mathrm{S}}_{x}$-treated InAs(001) and thermal stability of the surface have been studied by high-resolution x-ray photoelectron spectroscopy and low-energy electron diffraction. We find sulfur bonded to In and As atoms but no elemental sulfur for the as-treated surfac…
The effect of monomer structure and catalyst on the synthesis of hyperbranched polyesters based on 4,4-(4′-hydroxyphenyl)pentanoic acid has been examined. The nature of the ester group and the catalyst have a significant effect on the molecular weight of the hyperbranched polyester but do not effect the degree of bran…
In the present work, the influence of the substitution of Al for Mn on the structure and magnetic properties of TbMn6−xAlxSn6 compounds was investigated. With increasing Al concentration the lattice constants a, c, and the unit-cell volume V decrease monotonically. The TbMn6−xAlxSn6 compounds exhibit ferrimagnetic ord…
Efficient near infrared to visible upconversion luminescence is reported in the low phonon-energy host material ${\mathrm{Ba}}_{2}{\mathrm{YCl}}_{7}:x%$ ${\mathrm{Er}}^{3+}$ ($x=1,$ 10, 100). The upconversion mechanisms upon ${}^{4}{I}_{9/2}$ excitation $(\ensuremath{\approx}800\mathrm{nm})$ are investigated by means…
We have studied the photoluminescence mechanism of freshly prepared and naturally oxidized porous silicon by fluorescence-line-narrowing spectroscopy. The surfaces of fresh and oxidized porous silicon are terminated by silicon hydrides and silicon dioxide, respectively. The TO-phonon-related structure in resonantly ex…
Intrinsic localized radiative surface states belonging to Si-Si dimers on the surface of silicon nanocrystallites have been recently predicted. We examine the various photoexcitation pathways involved in populating these molecular states. We include both direct excitation from the ground state and indirect excitation…
The energy dependence of the relaxation of photoexcited electrons in copper was measured using femtosecond time-resolved photoemission spectroscopy to within 0.3 eV above the Fermi level. By performing lifetime measurements under different surface conditions, several surface dynamical processes were investigated. In p…
The miscibility of blends of phenolphthalein poly(ether ether sulfone) (PES-C) and poly(ethylene oxide) (PEO) was established on the basis of the thermal analysis results. Differential scanning calorimetry (DSC) studies showed that the PES-C/PEO blends prepared by casting from N,N-dimethylformamide (DMF) possessed a s…
The effects of a long-range electronic potential on a one-dimensional commensurate charge-density-wave state are investigated. Using numerical techniques it is shown that a transition to a metallic ground state is reached as the range of the electron-electron repulsion increases. In this metallic state, the optical co…
Remarkable features of local density of states (LDOS) at a single $n$-membered ring defect $(n=4,5,7,8)$ in monolayered graphite are described. Based on the $n$-fold rotational symmetry at the center of the $n$-membered ring, the wave functions and the spectra of these systems are classified into $n$ kinds of componen…
Within density-functional theory, we compute the Born effective charges of tungsten trioxyde in its reference cubic phase (defect-perovskite structure). For the tungsten atom, the effective charge tensor is isotropic, with ${Z}_{\mathrm{W}}^{*}=+12.51$. For the oxygen atoms, the two independent components of the tenso…
Two types of quantum magnetotransport behavior were observed in pristine bundles of helicoidal carbon nanotubes. Universal conductance fluctuations for $T<10$ K and an underlying positive magnetoconductance to very high magnetic fields for $T<100$ K are the most notable features of one of these types. Remarkably…
When an insulator is subject to electron irradiation, a fraction of electrons is absorbed while the rest is backscattered. The injected electrons cannot be definitely trapped but they must instead recombine with positive charges left near the irradiated surface when secondary electrons are emitted; this is justified o…
The difference between La-deficient and Sr-substituting effects for La in LaCoO${}_{3}$ has been investigated by using x-ray photoelectron spectroscopy (XPS). On the basis of the relationship between the intensity of the ${}^{2}{T}_{2}$ line and the amount of low-spin Co${}^{3+}$ ions in these compounds, it is pointed…
A genuine organic radical crystal 1,3,5-triphenyl-6-oxoverdazyl (TOV) has been revealed to be an S =1/2 two-dimensional (2D) weak-ferromagnetic Heisenberg antiferromagnet with the exchange interaction 2 J / k B =-9.0 K by the experiments of magnetic susceptibility, heat capacity, magnetization and electron paramagneti…
Poly(lactones) may be crosslinked by ring-opening polymerization of the corresponding cyclic esters in the presence of tetrafunctional bis(ϵ-caprolactone). The homopolymer of 1.5-dioxepan-2-one (DXO) has poor mechanical properties but also some very good properties, such as biocompatibility and degradability. Crosslin…
We have proposed a possible crystal structure for the cluster-assembled solid Al${}_{12}$C(Si), and its electronic structures and stability have been studied in the framework of density functional theory and ab initio molecular dynamics. We find that Al${}_{12}$C(Si) clusters are condensed by van der Waals force, with…
Phosphorus-containing polyurethanes are synthesized by reacting phosphorus-containing diisocyanates, bis (4-isocyanatophenoxy) phenyl phosphine oxide (BIPPO) and bis (3-isocyanatophenyl) phenyl phosphine oxide (BIPPPO), with various diols. The chemical structures of the obtained monomers and polymers are characterized…
In computing the volume occupied by atoms and the density in proteins, one is faced with the problem of intersecting spheres. To estimate either, the space between the atoms has to be divided according to the location of the atoms relative to each other. Various methods, based on Voronoi's idea of approximating the at…