Materials Literature
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In this letter, we report an oleic acid (OA)-capped CdSe quantum-dot sensitized solar cell (QDSSC) with an improved performance. The TiO2/OA-CdSe photoanode in a two-electrode device exhibited a photon-to-current conversion efficiency of 17.5% at 400 nm. At AM1.5G irradiation with 100 mW/cm2 light intensity, the QDSSC…
This Forum Article overviews the recent amalgamation of two long-established areas, manganese/oxo coordination cluster chemistry involving the higher Mn(II)/Mn(IV) oxidation states and transition-metal azide (N(3)(-)) chemistry. The combination of azide and alkoxide- or carboxylate-containing ligands in Mn chemistry h…
We demonstrate experimentally and numerically that nonplanar chiral metamaterials give giant optical activity, circular dichroism, and negative refractive index. The transmission, reflection, and the retrieval results of the experiments agree pretty well with the simulations. This is an important step toward the desig…
The positronium state in quartz is described by a linear superposition of two states: the first describing the free positron in the crystal and the second corresponding to a positronium Bloch wavefunction in the lattice. The condition for positronium formation in the electron gas is deduced by using variational calcul…
Mountains on rapidly rotating neutron stars efficiently radiate gravitational waves. The maximum possible size of these mountains depends on the breaking strain of neutron star crust. With multi-million ion molecular dynamics simulations of Coulomb solids representing the crust, we show that the breaking strain of pur…
Density of the polyacrylamide ultrathin films has been studied using X-ray reflectivity technique. Two sources (one powder and another aqueous solution) of polyacrylamide were used to prepare spin coated films on silicon substrate. Light scattering measurements show that the polymer chains were unentangled in a concen…
The effect of annealing on the dynamical behavior of swelling for ultrathin polyacrylamide films deposited on silicon substrates have been studied using X-ray reflectivity technique. The spin coated polyacrylamide films of similar thicknesses were annealed at various temperatures below and above the glass transition t…
The issue of quantum size effects of interactive electron-hole systems in spherical semiconductor quantum dots is put to question. A sharper theoretical approach is suggested based on a new pseudo-potential method. In this new setting, analytical computations can be performed in most intermediate steps lending stronge…
The coupling between localized spins and phonons can lead to shifts in the dielectric constant of insulating materials at magnetic ordering transitions. Studies on isostructural SeCuO3 (ferromagnetic) and TeCuO3 (antiferromagnetic) illustrate how the q-dependent spin-spin correlation function couples to phonon frequen…
We have demonstrated the thickest bulk photonic metamaterial reported in the literature based on an Ag-filled alumina membrane. The material is highly anisotropic with hyperbolic dispersion at λ>0.84 μm. The refraction of light in the direction expected of isotropic media with n<1 has been experimentally…
Raman scattering from single gold nanostars coated with self-assembled monolayers of 4-mercaptobenzoic acid is observed. The Raman signal can be detected without the need of forming particle aggregates or resonant electronic excitation of the analyte. A total Raman enhancement factor of 107 for individual nanostars is…
Photomagnetism in molecular systems is a new development in molecular magnetism. It traces back to 1982 and 1984 when a transient effect and then the light-induced excited-spin-state-trapping effect was discovered in spin-crossover complexes. The present contribution gives a definition of the phenomenon, a process tha…
Ferrites of the type M II Fe 2 O 4 (M = Fe and Co) have been prepared by the traditional coprecipitation method. These ferrites were modified by the adsorption of fatty acids derived from soybean and castor oil and were then dispersed in cyclohexane, providing very stable magnetic fluids, readily usable in nonpolar me…
We report phonon renormalization in bilayer graphene as a function of doping. The Raman $G$ peak stiffens and sharpens for both electron and hole doping as a result of the nonadiabatic Kohn anomaly at the $\ensuremath{\Gamma}$ point. The bilayer has two conduction and valence subbands, with splitting dependent on the…
Magnetic order in graphene-related structures can arise from size effects or from topological frustration. We introduce a rigorous classification scheme for the types of finite graphene structures (nanoflakes) which lead to large net spin or to antiferromagnetic coupling between groups of electron spins. Based on this…
Slow relaxation of the magnetization (i.e., "magnet-like" behavior) in materials composed of magnetically isolated chains was observed for the first time in 2001. This type of behavior was predicted in the 1960s by Glauber in a chain of ferromagnetically coupled Ising spins (the so-called Glauber dynamics). In 2002, t…
Raman scattering of molecules adsorbed on the surface of TiO(2) nanoparticles was investigated. We find strong enhancement of Raman scattering in hybrid composites that exhibit charge transfer absorption with TiO(2) nanoparticles. An enhancement factor up to approximately 10(3) was observed in the solutions containing…
The first two families of polyoxometalate-based single-molecule magnets (SMMs) are reported here. Compounds of the general formula [Ln(W(5)O(18))(2)](9-) (Ln(III) = Tb, Dy, Ho, and Er) and [Ln(SiW(11)O(39))(2)](13-) (Ln(III) = Tb, Dy, Ho, Er, Tm, and Yb) have been magnetically characterized with static and dynamic mea…
Heterometallic 3d-4f complexes are of high interest in molecular magnetism: the lanthanide ions bring large and, in most cases, anisotropic magnetic moments. The combination of 3d and 4f metal ions, which differ through their chemistries and stereochemical preferences, leads to a rich variety of heterometal complexes,…
Abstract Micropatterns of cells on a poly(vinyl chloride) (PVC) film surface were created by using ion irradiation. A PVC film was irradiated with H + ions through a pattern mask in order to create patterns of the hydrophilic/hydrophobic regions on the PVC surface. The effect of ion irradiation on the surface properti…