Microsolvation of LiH+ in helium clusters: many-body effects and additivity models for the interaction forces

The ab initio calculation of the interaction forces between the LiH+ molecular ion, at its equilibrium geometry, and several He atoms is carried out in order to isolate and assess the importance of many-body contributions in the search for realistic energy and geometry data. The full potential energy surface (PES) with a single helium partner is obtained first by using an aug-cc-pVQZ basis set for He and higher quality ones for Li and H. The calculations were performed at the CAS-SCF plus MRCI level for the lowest potential energy surface over a total of 480 grid points of the two intermolecular Jacobi coordinates, whereas the excited state surface has also been examined in order to exclude the presence of any significant nonadiabatic interaction between the two PESs. A numerical fit of the lower surface is presented and the general physical changes of the ionic interaction when going from the lower to the upper of the two potentials are described and discussed. The fairly limited importance of many-body effects for such systems is seen from further ab initio calculations including several He atoms: our results suggest that, at least in the present case, no strong charge migration occurs after He attachment, and therefore, one could realistically model larger clusters by implementing a sum-of-potentials approach via the presently computed PES.     

Critical currents in quasiperiodic pinning arrays: chains and Penrose lattices

We study the critical depinning current Jc versus the applied magnetic flux Phi, for quasiperiodic (QP) chains and 2D arrays of pinning centers placed on the nodes of a fivefold Penrose lattice. In QP chains, the peaks in Jc(Phi) are determined by a sequence of harmonics of the long and short segments of the chain. The critical current Jc(Phi) has a remarkable self-similarity. In 2D QP pinning arrays, we predict analytically and numerically the main features of Jc(Phi), and demonstrate that the Penrose lattice of pinning sites provides an enormous enhancement of Jc(Phi), even compared to triangular and random pinning site arrays. This huge increase in Jc(Phi) could be useful for applications.     

Strong interaction corrections to CP violation in B0-B0 mixing

We calculate, in the framework of the standard six-quark model and QCD, the corrections due to strong interactions to the transition width for the $\text{B}{}^0\text{-}\text{B}{}^0$ system, focusing our attention on CP-violating effects.     

Ab initio valence bond calculations. X. Vertical valence ionization potentials of allene and butatriene

The ground and vertical valence ionized states of allene and butatriene have been studied in the ab initio valence bond framework using the 6–31G basis set after contraction and introducing the core–valence shell separation. The final wave functions have been analyzed in terms of VB structures by means of population analysis.     

An EPR study of rhodium oxihydroxide

Rhodium oxihydroxide has been synthesized by means of hydrothermal synthesis at 1500 bars and 600°C in acidic media. Powder X-ray diffraction shows small variations in cell parameters which appear to be related to the oxidizing power of the reaction media. On the basis of EPR work such variations can be attributed to the presence of small amounts of either Rh(II) or Rh(IV). This last species had not been fully characterized before by EPR in oxide-like materials. The paramagnetic species seem to be noninteracting and randomly distributed in the Rh(III) sites. These results can be understood on the basis of two different kinds of nonstoichiometry for rhodium oxihydroxide: either proton or hydroxyl ion defects.     

Les états de coaction. Aspects spécifiques et influence opérationnelle

Meccanica - Il rapporto si propone di delineare gli aspetti specifici degli equilibri per coazione. A tal fine vengono, in primo luogo, raffrontati gli equilibri da forze e quelli da deformazioni...     

Tetraphenylethylene-BODIPY aggregation-induced emission luminogens for near-infrared polymer light-emitting diodes

The aggregation-induced emission(AIE) phenomenon provides a new direction for the development of organic light-emitting devices. Here, we present a new class of emitters based on 4,4-difluoro-4-bora-3 a,4 a-diaza-s-indacene(BODIPY), functionalized at different positions with tetraphenylethylene(TPE), which is one of the most famous AIE luminogens. Thanks to this modification, we were able to tune the photoluminescence of the BODIPY moiety from the green to the near-infrared(NIR)spectral range and achieve PL efficiencies of ~50% in the solid state. Remarkably, we observed an enhancement of the AIE and up to ~100% photoluminescence efficiencies by blending the TPE-substituted BODIPY fluorophores with a poly[(9,9-di-noctylfluorene-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)](F8 BT) matrix. By incorporating these blends in organic lightemitting diodes(OLEDs), we obtained electroluminescence peaked in the range 650–700 nm with up to 1.8% external quantum efficiency and ~2 m W/cm2 radiance, a remarkable result for red/NIR emitting and solution-processed OLEDs.     

Effect of the solvent on growth and properties of polyaniline-based composite films

In this study, we report on the electrosyntheses of polyaniline (PAni) and PAni/magnetite nanoparticle (PAni/Fe₃O₄-NP) composite films by a potentiodynamic method from water and ethanol solutions. The aim of the study is to evaluate the effect of the solvent on the electrochemical growth of these films. The growth cyclic voltammograms and the mass change variation (Δm), determined by the electrochemical quartz crystal microbalance technique, show that the polymer growth rate is lower in ethanol than in water (Δm in water is ca. 50% higher than in ethanol after 30 voltammetric cycles). As a consequence, the films grown from ethanol show a more compact and uniform morphology, as we observed with scanning electron microscopy. Furthermore, the formation of oxidation products is inhibited in ethanol. The PAni/Fe₃O₄-NP composite films electrosynthesized in ethanol showed enhanced electrochemical response than the composite films grown from water. This is attributed to the better dispersion of the nanoparticles in this solvent and consequently in the polymer matrix, as confirmed by the Δm value and the spectroscopic characterization. We conclude that electropolymerization from ethanol solution provides high-quality PAni and PAni/Fe₃O₄-NP composite films; the electrochemical and morphological properties of these films suggest that their use for corrosion protection is promising.     

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO2 Reduction to CO

We report here the first purely organometallic fac‐[Mn^I(CO)₃(bis‐^MeNHC)Br] complex with unprecedented activity for the selective electrocatalytic reduction of CO₂ to CO, exceeding 100 turnovers with excellent faradaic yields (η_CO≈95 %) in anhydrous CH₃CN. Under the same conditions, a maximum turnover frequency (TOF_max) of 2100 s^?1 was measured by cyclic voltammetry, which clearly exceeds the values reported for other manganese‐based catalysts. Moreover, the addition of water leads to the highest TOF_max value (ca. 320 000 s^?1) ever reported for a manganese‐based catalyst. A Mn^I tetracarbonyl intermediate was detected under catalytic conditions for the first time.