Search results for "hell"

Synthesis and characterization of GaN/ReS2, ZnS/ReS2 and ZnO/ReS2 core/shell nanowire heterostructures

2020

This research was funded by the ERDF project “Smart Metal Oxide Nanocoatings and HIPIMS Technology”, project number: 1.1.1.1/18/A/073. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART².

Silica nanoparticle core structure examined by the E?Si? center 29Si strong hyperfine interaction

2015

Abstract β-Ray irradiation up to 1.2 GGy was employed to induce E′Si γ defects and to study the structure of silica nanoparticles with diameters from 7 up to 20 nm. Defect concentration and their 29 Si strong hyperfine doublet were investigated through electron paramagnetic resonance measurements. Our data indicate that stable defects are located in the nanoparticle core. Furthermore, the E′Si γ hyperfine interaction evidences that the core structure is denser than bulk silica and independent from the particle size. Finally, we put in evidence that the core structure is stable and unaffected by the irradiation in the investigated dose range maintaining the specific features of nanoparticles.

Co-crystallization of atomically precise metal nanoparticles driven by magic atomic and electronic shells

2018

This paper reports co-crystallization of two atomically precise, different-size ligand-stabilized nanoclusters, a spherical (AuAg)267(SR)80 and a smaller trigonal-prismatic (AuAg)45(SR)27(PPh3)6 in 1:1 ratio, characterized fully by X-ray crystallographic analysis (SR = 2,4-SPhMe2). The larger cluster has a four concentric-shell icosahedral structure of Ag@M12@M42@M92@Ag120(SR)80 (M = Au or Ag) with the inner-core M147 icosahedron observed here for metal nanoparticles. The cluster has an open electron shell of 187 delocalized electrons, fully metallic, plasmonic behavior, and a zero HOMO-LUMO energy gap. The smaller cluster has an 18-electron shell closing, a notable HOMO-LUMO energy gap and…

Pressure effects on the electronic and optical properties ofAWO4wolframites (A =Cd, Mg, Mn, and Zn): The distinctive behavior of multiferroic MnWO4

2012

The electronic band-structure and band-gap dependence on the $d$ character of ${A}^{2+}$ cation in $A$WO${}_{4}$ wolframite-type oxides is investigated for different compounds ($A$ $=$ Mg, Zn, Cd, and Mn) by means of optical-absorption spectroscopy and first-principles density-functional calculations. High pressure is used to tune their properties up to 10 GPa by changing the bonding distances establishing electronic to structural correlations. The effect of unfilled $d$ levels is found to produce changes in the nature of the band gap as well as its pressure dependence without structural changes. Thus, whereas Mg, Zn, and Cd, with empty or filled $d$ electron shells, give rise to direct and…

Moisture barrier, wetting and mechanical properties of shellac/agar or shellac/cassava starch bilayer bio-membrane for food applications

2008

Abstract Edible bilayer membrane composed of agar (AG) or cassava starch (CAS) as a cohesive structural layer and ethanol-cast shellac layer as a moisture barrier are investigated for their potential use in food preservation as bio-packaging film, membrane or coating. Bilayer membranes containing non-plasticized shellac exhibit low water vapor permeability (WVP), from 0.89 to 1.03 × 10 −11  g m −1  s −1  Pa −1 . A high value of contact angle (≈92°) and a low liquid water adsorption rate (26 × 10 −3  μL s −1 ) indicate that these barrier layers have a quite hydrophobic surface. However, the rigid and brittle characteristics of shellac induce a lack of integrity for this layer. It tends to be…

Pd supported on magnetic carbon coated halloysite as hydrogenation catalyst: Study of the contribution of carbon layer and magnetization to the catal…

2019

Abstract In this article, a magnetic carbon-coated halloysite nanoclay (Hal) was prepared through introduction of hydrothermally carbonized glucose (Glu) on Hal followed by the immobilization of magnetic nanoparticles (MNPs) and incorporation of resorcinol-formaldehyde polymeric shell (RF) and carbonization. The resulting composite was then successfully applied for the immobilization of Pd nanoparticles to afford Pd@Hal@Glu-Fe-C that could efficiently promote hydrogenation of nitroarenes in the aqueous media at low temperature. The catalyst exhibited high selectivity toward nitro group. Moreover, it was highly recyclable with low MNPs and Pd leaching. To elucidate the contribution of each c…

Core–Shell Nanoparticles: Design of Bistable Gold@Spin‐Crossover Core–Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching (…

2019

Electronic Shell Structure and the Crystal Field Splitting in Simple Metals Clusters

1991

An upper limit for the number of atoms in metal clusters capable of exhibiting electronic shell structure has been estimated by comparing the energy difference between the highest occupied and the lowest unoccupied state with the crystal field splitting. The former is obtained by solving the Schrodinger equation for a spherical potential well with hard walls while the latter is obtained from the band structure of the solid. The results indicate that shell structures may persist in clusters containing as many as a million atoms.

Ultrastrong Coupling of Plasmons and Excitons in a Nanoshell

2014

The strong coupling regime of hybrid plasmonic-molecular systems is a subject of great interest for its potential to control and engineer light-matter interactions at the nanoscale. Recently, the so-called ultrastrong coupling regime, which is achieved when the light-matter coupling rate reaches a considerable fraction of the emitter transition frequency, has been realized in semiconductor and superconducting systems and in organic molecules embedded in planar microcavities or coupled to surface plasmons. Here we explore the possibility to achieve this regime of light-matter interaction at nanoscale dimensions. We demonstrate by accurate scattering calculations that this regime can be reach…

Towards tunable defect arrangements in smectic liquid crystal shells utilizing the nematic–smectic transition in hybrid-aligned geometries

2012

We produce and investigate liquid crystal shells with hybrid alignment—planar at one boundary, homeotropic at the other—undergoing a transition between the nematic (N) and smectic-A (SmA) phases. The shells display a dynamic sequence of patterns, the details depending on the alignment agents and on the diameter and thickness of the shell. In shells of sufficient diameter we typically find a transient striped texture near the N–SmA transition, stabilising into a pattern of tiled, more or less regularly spaced focal conic domains in the SmA phase. The domain size and spacing decrease with reduced shell thickness. In case of strong homeotropic anchoring at one boundary and small shell size, ho…