Materials Literature
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Amorphous carbon films with variable sp3 content were produced by ArF (193 nm) pulsed laser deposition. Electron energy loss spectroscopy and spectroscopic ellipsometry were employed to systematically study changes in the bonding and optical properties of the carbon films as a function of the kinetic energy of ablated…
Transient absorption spectra of ion-implanted Si nanocrystals (NCs) exhibit two picosecond photoinduced absorption features, attributed to carriers in NC quantized states (high-energy band) and Si/SiO2 interface states (low-energy band). Fast relaxation of the high-energy band indicates that populations of quantized s…
The ability of novel tetraazatriphenylenes to sensitise the luminescence of different lanthanide ions is reported. An example of the type of lanthanide complex formed is depicted. The influence of the ligand–structure variation on the absorption characteristics and other photophysical properties of the sensitiser was…
We have measured the photoelectron spectra of mass-selected negatively charged mercury clusters ${\mathrm{Hg}}_{n}^{\ensuremath{-}}$ in the size range $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3--250$. The spectra are characterized by gaps which shrink with increasing $n$. These gaps represent the $s\ensure…
The low carrier mobility of the magnetic perovskite ${\mathrm{Nd}}_{0.52}{\mathrm{Sr}}_{0.48}{\mathrm{MnO}}_{3}$ implies that the dominant conductivity mechanism is related to Mott hopping. We propose a modification of Mott's original model by taking into account that the hopping barrier depends on the misorientation…
Two versatile luminescence ion probes for potassium ions have been designed based on the “switching on and off” of the gold–gold interaction. Addition of potassium ions to the gold(I) complexes [Au2(R2PCH2PR2)(S-benzo[15]crown-5)2] (see the picture; R=Ph, cyclohexyl; M+=K+) give rise to an intense red luminescence.
Molecular recognition and electrostatic interaction of oppositely charged polyelectrolytes are combined in the fabrication of ultrathin metallosupramolecular multilayers [shown schematically in the picture, PEI=polyethyleneimine, PSS=poly(styrene sulfonate)]. The layers between the PSS layers are composed of an iron(I…
Homoepitaxial growth is unstable towards the formation of pyramidal mounds when interlayer transport is reduced due to activation barriers to hopping at step edges. Simulations of a lattice model and a continuum equation show that a small amount of desorption dramatically speeds up the coarsening of the mound array, l…
On the basis of the pseudopotential plane-wave (PP-PW) method in combination with the local density functional theory (LDFT), complete stress-strain curves for the uniaxial loading and uniaxial deformation along the [001] and [111] directions, and the biaxial proportional extension along [010] and [001] for aluminium…
The mysterious coexistence of ferromagnetism and charge ordering in ${\mathrm{La}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{MnO}}_{3}$ is found to result from an inhomogenous spatial mixture of incommensurate charge-ordered and ferromagnetic charge-disordered microdomains with a size of 20--30 nm. Furthermore, high resolution…
Abstract The structure and dynamics of silica hard spheres and charged colloidal systems has been investigated at high concentrations by means of light scattering. The index of refraction at these high volume fractions was matched using a mixture of water/isopropanol for the Yukawa particles and toluene/ethanol for th…
The magnetoelastic contribution ΔĈ (3) to the effective third-order elastic constants Ĉ (3) ef is determined; it describes the additional elastic anharmonicity induced by nonlinear spin-spin and spin-phonon interactions in ferromagnets. In the vicinity of magnetoacoustic resonance, this anharmonicity can be manifested…
Ga, Tl, Sn, Pb, As, Sb, Bi, Cd, and Hg chlorides react with magnesium anthracene · 3 THF (MgA), anthracene-activated magnesium, or “active magnesium” (Mg*) in THF, generating the respective Mg intermetallics in a nanocrystalline or amorphous state (Eqs. 1–3). Mg intermetallics accessible through the wet-chemical route…
Abstract Crystallization of natural rubber (NR) and trans -1,4-polyisoprene (TPI) in blends with styrene—butadiene rubber (SBR) has been studied dilatometrically. For TPI, the melting temperature and Avrami index of crystallization kinetics were unchanged by blending with SBR. However, the rate of crystallization was…
Synchrotron radiation offers several advantages over the use of rotating anode sources for biological crystallography, which allow for the collection of higher-resolution data, substantially more rapid data collection, phasing by multiwavelength anomalous diffraction (MAD) techniques, and time-resolved experiments usi…
Two related and not thoroughly resolved issues in biochemistry concern the role, if any, of enzyme surfaces in routine metabolism and the method by which metabolic intermediates move between enzyme active sites during multi-step degradation or synthesis. An important enzyme for which a detailed three-dimensional struc…
Calculations of the phonon spectrum of crystalline In 4 Se 3 in a model of central-pair interactions with neglect of the long-range forces are presented. The model developed contains five unknown parameters, which are determined from experimental values of the elastic moduli without consideration of the internal displ…
A study of cathodoluminescence spectra of silicon oxide films grown thermally on silicon is reported. It has been established that the cathodoluminescence properties of thermal films are nonuniform in depth and depend on the growth conditions and characteristics of the silicon substrate.
Seedless crystallization of Ge and GaSb melts was achieved under microgravity occurring in a drop-shaft capsule. It was observed that melts levitated in Ar atmosphere, formed into a spherical shape and were solidified instantaneously when they collided with the container quartz wall. X-ray diffraction pattern of these…
2-Diphenylphosphino-phenol was chosen as an ambivalent (hard/soft) chelating ligand for biologically important first row transition metals. The expected mode of complexation is relevant to trapping of metal ions in humic acids and related environmental ion exchange systems with phenolate functions. The 1:2 complex wit…