Materials Literature
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This paper describes the synthesis of polylactide-functionalized polyoxanorbornenes and their hydrolytic degradation behavior. Macromonomers with one or two exo -PLA chains as well with two endo,exo chains were prepared using tin(II) 2-ethylhexanoate as a catalyst in the presence of mono- or dialcohol derivatives of o…
Nanoparticle technologies open the routes for nanostructured materials which combine individual physical properties or generate new functions. In the field of ferroelectric materials the development of dense nanocomposites requires breakthroughs in the elaboration step. Here, we propose a flexible process to obtain fe…
Regular arrays of rectangular gold nanoparticles placed on gold films are characterized by using linear reflection spectroscopy (in the wavelength range of $450--950\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$) and nonlinear scanning optical microscopy, in which two-photon photoluminescence (TPL) excited with a strongly fo…
Abstract Deep‐red moisture and air sensitive single crystals of K 4 Ge 9 were obtained by reacting GeO 2 and elemental Ge with metallic W and K at high temperature in a niobium ampoule. The crystal structure of the compound was determined by single crystal X‐ray diffraction experiments. K 4 Ge 9 crystallizes in a pola…
Abstract Crystal growth of the trigonal form of isotactic poly(butene‐1) ( it ‐PB1) was successfully observed in the melt at atmospheric pressure. The growth rate of trigonal crystals was obtained by in situ optical microscopy. It is one hundredth that of it ‐PB1 tetragonal crystals. The growth rate of trigonal crysta…
Ag ist nicht Cu: Bei der heterogen katalysierten Reaktion von coadsorbiertem Sauerstoff mit Propylen (siehe Bild, O rot, Propylen gelb/grün) resultiert der unterschiedliche Verlauf an Ag- und Cu-Oberflächen DFT-Rechnungen zufolge aus dem ersten Reaktionsschritt. Die Basizität des O-Atoms an Ag führt zur Abspaltung ein…
Nanostructures, such as quantum dots, nanocrystals and nanowires, made of wurtzite ZnO have recently attracted attention due to their proposed applications in optoelectronic devices. Raman spectroscopy has been widely used to study the optical phonon spectrum modification in ZnO nanostructures as compared to bulk crys…
Clay minerals, and within these, the smectite group, including the hectorites in focus, possess layered structures, in which interlayer chemistry may be applied to functionalize them optically. While luminescence from organic dyes has previously been described in the structurally closely related montmorillonites, atte…
RNA-mediated fluorescent PbS nanoparticles have been synthesized in the quantum-confined region of a face-centered cubic phase. The binding of RNA to the surface of PbS nanoparticles has been exploited to tailor its size and to improve the stability and electronic properties. These particles display excitonic features…
In the past two decades mid-IR nonlinear optical crystals have grown from scientific curiosities to practical robust materials generating efficient, multi-watt output in the 3-12&mgr;m spectral range. Nonetheless, improved NLO crystals are critical for further advancing mid-IR laser development. In particular, mid-IR…
A novel photochromic helicenoid diarylethene (R)-1-[1-(1-methoxymethoxyethyl)-2-naphtho[2,1-b]thienyl]-2-(2,4,5-trimethyl-3-thienyl)hexafluorocyclopentene was synthesized enantioselectively. It showed highly diastereoselective photocyclization (90% de) and a large change (950 degrees) in the specific optical rotation…
The point defect and diffusion properties of A15 ${\mathrm{Nb}}_{3}\mathrm{Sn}$ are investigated using ab initio density functional theory calculations and statistical thermodynamics. The defect structure is found to be of antisite type, with small amounts of Nb vacancies, and Sn vacancies showing a trend towards inst…
Recent scanning tunneling microscopy studies of individual organic molecules on Si(001) reported negative differential resistance (NDR) above a critical applied field, observations explained by a resonant tunneling model proposed prior to the experiments. Here we use both density functional theory and a many-electron…
Swelling behaviors of cellulose I(alpha) and III(I) crystals have been studied using molecular dynamics simulations of the solvated finite-crystal models. The typical crystal models consisted of 48 x 10-mer chains. For the cellulose I(alpha) crystal, models consisting of different numbers of chains and chain lengths w…
The lowest energy structures and the diffusion energy barriers of small M N ( N = 1–4) Ag and Au clusters absorbed on the regular MgO (100) surface are investigated via density-functional (DF) calculations, using two different xc-functionals (PBE and LDA). In agreement with previous work, it is found that the lowest-e…
The low quantum yield of luminescence in the NIR region of small (1.8 nm) gold nanoparticles stabilized with triphenylphosphine (TPP) increases by at least 2 orders of magnitude when TPP is replaced with a pyrene derivative. Very efficient energy transfer from the bound fluorophores to the gold core was observed, lead…
We study the dynamics of long-wavelength fluctuations in one-dimensional (1D) many-particle systems as described by self-consistent mode-coupling theory. The corresponding non-linear integro-differential equations for the relevant correlators are solved analytically and checked numerically. In particular, we find that…
Here we present a layer-by-layer (LbL) assembled device architecture that serves as a model heterostructure to study the atypical assembly that can result from the bottom-up combination of multiple multilayers of different compositions. Heterostructure assembly is disrupted by diffusion of linear poly(ethylene imine)…
In the 1960s, Samson solved the structures of some of the most complicated intermetallic phases known, including those of NaCd(2), Mg(2)Al(3), and Cu(3)Cd(4) (each with over 1000 atoms per unit cell). Following remarkable earlier constructions by Samson and by Andersson, we use quantum-mechanical calculations as a gui…
It is of fundamental importance to be able to easily distinguish between the viscoelastic properties of a molecular gel (noncovalent cross-linked three-dimensional polymer structure) and a brush (polymer structure that emanates from a surface in three dimensions without cross-linking). This has relevance in biology an…