Materials Literature
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We develop a dimensional regularization approach to deal with the low-energy effects of the long-range Coulomb interaction in 1D electron systems. The method allows us to avoid the infrared singularities arising from the long-range Coulomb interaction at D = 1, providing at the same time insight about the fixed-points…
Density distribution of cold exciton clouds generated into a strain-induced potential well by two-photon excitation in Cu$_2$O is studied at 2 K. We find that an anomalous spike, which can be interpreted as accumulation of the excitons into the ground state, emerges at the potential minimum. The accumulation can be du…
Heat bath Monte Carlo simulations have been used to study a four-state clock model with a type of random field on simple cubic lattices. The model has the standard nonrandom two-spin exchange term with coupling energy $J$ and a random field which consists of adding an energy $D$ to one of the four spin states, chosen…
Coherent misfitting precipitates in elastically stressed media such as $γ\prime$ particles in nickel-based super-alloys show various splitting patterns such as doublets, quartets, or octets due to their misfit strain energy. While it is an interesting instability phenomenon defying conventional surface thermodynamics,…
This paper investigates the relationship between cure temperature, morphology, and mechanical properties of di-, tri-, and tetrafunctional high-performance, epoxy layered-silicate nanocomposites. Wide-angle X-ray analysis (XRD) was carried out at different stages of cure to monitor organoclay exfoliation kinetics. It…
Using an imaging mode based on the adjustment of a negative value of the spherical-aberration coefficient of the objective lens of a transmission electron microscope, we successfully imaged all types of atomic columns in the dielectric SrTiO3 and the superconductor YBa2Cu3O7. In particular, we were able to view the ox…
Photoelectron spectroscopy revealed that a 20-atom gold cluster has an extremely large energy gap, which is even greater than that of C60, and an electron affinity comparable with that of C60. This observation suggests that the Au20 cluster should be highly stable and chemically inert. Using relativistic density funct…
Reversible color change of a neutral chromophore in a cationic zeolite was achieved by controlling the direct interaction between alkali-metal cations and chromophores. As a typical combination of the cationic host and the neutral chromophore, Na + -type mordenite accommodating N,N -dimethyl- p -nitroaniline (DMpNA) w…
Geringes Erhitzen genügt, um kristallines 2,5-Dibrom-3,4-ethylendioxythiophen in ein gut leitendes, bromdotiertes Poly(3,4-ethylendioxythiophen) (PEDOT) zu überführen. Die Leitfähigkeit des Polymers kann durch Dotierung mit Iod weiter erhöht werden. Mit dieser Methode können auch dünne Filme von PEDOT mit einer Leitfä…
Microporous silica solids of SiO 2 and Ag/SiO 2 (a microporous SiO 2 substrate containing 5 wt % Ag) are synthesized by the sol−gel method and analyzed through several characterization techniques. The type I shapes of N 2 sorption isotherms at 76 K on these materials indicate large micropore contents as well as import…
This study shows the response of silicon nanotubes (SiNTs) under axial compression using an atomistic simulation based on the Tersoff potential. The application of pressure, proportional to the deformation within Hook’s law, eventually led to a collapse of the SiNT and an abrupt change in structure. Using the sum of t…
Ein Through-Space-Superaustausch scheint für die Ladungsrekombination (CR) nach Photoanregung und Ladungstrennung (CS) in Zinkporphyrin-C60-Rotaxanen maßgeblich zu sein (siehe Bild). Darauf weist die niedrige Aktivierungsenergie dieses Prozesses hin, an dem außerdem ein relativ langlebiger Ladungstrennungszustand bete…
Cupric complexes of a novel phenanthroline-phenolate ligand have strongly distorted coordination geometries and electrochemical properties conducive to modeling the spectroscopy and reactivity of the enzyme galactose oxidase.
Abstract Two homologues of novel triphenylene mesogens possessing –O(CH2)3CF3 (F1) and –O(CH2)3(CF2)5CF3 (F6) were synthesized and investigated on the mesomorphic behavior to reveal that these show a hexagonal columnar (Colh) mesophase. The mesomorphic behavior is obviously different from those of the corresponding hy…
Die Krönung: Die L-förmige Baueinheit [Ln(H2O)2(α-AsW9O33)]6− (Ln=Lanthanoid) ermöglicht den eleganten Aufbau kronenförmiger Strukturen [{Ln(H2O)2(α-AsW9O33)}n]6n− (n=gerade Zahl ≥4), die Kationen einschließen können. Die Mühlrad-Propellerstruktur links besteht aus einem K+-Ion und sechs [α-AsW9O33]9−-Liganden, in der…
Structural proteomics is the determination of atomic resolution three-dimensional protein structures on a genome-wide scale in order to better understand the relationship between protein sequence, structure, and function. Here we describe our ongoing structural proteomics project on the nonmembrane proteins of the arc…
Abstract In the Cu(1 – x )Cr x VS system CuCr 1– x V x S 2 solid solutions isostructural with CuCrS 2 and Cu 3 VS 4 were found by replacement of Cr by V up to x = 0.20. The oxidation states of Cr and V were determined from structural data and paramagnetic susceptibility measurements. The CuCr 1– x V x S 2 solid soluti…
A method for cooling by the application of pressure was recently proposed. As in any other (magnetic) adiabatic cooling technique, the cooling results from a change in the magnetic entropy of the system under investigation. As opposed to the well known method of adiabatic demagnetization (for paramagnets) or to the ma…
The molecular and crystal structures of solvent-free potassium, rubidium, and cesium oxalates have been determined ab initio from high-resolution synchrotron and X-ray laboratory powder patterns. In the case of potassium oxalate K(2)C(2)O(4) (a = 10.91176(7) A, b = 6.11592(4) A, c = 3.44003(2) A, orthorhombic, Pbam, Z…
We present a consistent approach to the study of single (isolated) defects in crystals. This has three stages: (i) band structure calculation of a perfect host crystal is used to define the shape and size of the supercell adequately modeling a perfect crystal, (ii) further supercell point defect calculation for unrela…