scholarly journals Tunneling between parallel one-dimensional Wigner crystals

Author(s):  
Reyna Mendez-Camacho ◽  
Esteban Cruz-Hernandez

Abstract Vertically aligned arrays are a frequent outcome in the nanowires synthesis by self-assembly techniques or in its subsequent processing. When these nanowires are close enough, quantum electron tunneling is expected between them. Then, because extended or localized electronic states can be established in the wires by tuning its electron density, the tunneling configuration between adjacent wires could be conveniently adjusted by an external gate. In this contribution, by considering the collective nature of electrons using a Yukawa-like effective potential, we explore the electron interaction between closely spaced, parallel nanowires while varying the electron density and geometrical parameters. We find that, at a low-density Wigner crystal regime, the tunneling can take place between adjacent localized states along and transversal to the wires axis, which in turn allows to create two- and three-dimensional electronic distributions with valuable potential applications.

2018 ◽  
Vol 74 (8) ◽  
pp. 894-900 ◽  
Author(s):  
Lin Wang ◽  
Qian-Kun Zhou ◽  
Yun Xu ◽  
Ni-Ya Li

In recent years, the design and construction of crystalline coordination complexes by the assembly of metal ions with multitopic ligands have attracted considerable attention because of the unique architectures and potential applications of these compounds. Two new coordination polymers, namely poly[[μ-trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene-κ2 N:N′](μ3-5-methylisophthalato-κ4 O 1,O 1′:O 3:O 3′)cadmium(II)], [Cd(C9H6O4)(C12H11N3)] n or [Cd(5-Me-ip)(2-NH2-3,4-bpe)] n , (I), and poly[[μ-trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene-κ2 N:N′](μ2-5-hydroxyisophthalato-κ4 O 1,O 1′:O 3:O 5)cadmium(II)], [Cd(C8H4O5)(C12H11N3)] n or [Cd(5-HO-ip)(2-NH2-3,4-bpe)] n , (II), have been prepared hydrothermally by the self-assembly of Cd(NO3)2·4H2O and trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene (2-NH2-3,4-bpe) with two similar dicarboxylic acids, i.e. 5-methylisophthalic acid (5-Me-H2ip) and 5-hydroxyisophthalic acid (5-HO-H2ip). The coordination network of (I) is a two-dimensional sql net parallel to (101). Adjacent sql nets are further linked to form a three-dimensional supramolecular framework via hydrogen-bonding interactions. Compound (II) is a two-dimensional (3,5)-connected coordination network parallel to (010) with the point symbol (63)(55647). As the other reactants and reaction conditions are the same, the structural differences between (I) and (II) are undoubtedly determined by the different substituent groups in the 5-position of isophthalic acid. Both (I) and (II) exhibit good thermal stabilities and photoluminescence properties.


2014 ◽  
Vol 699 ◽  
pp. 318-324 ◽  
Author(s):  
Syara Kassim ◽  
S. Padmanabhan ◽  
J. McGrath ◽  
M.E. Pemble

The bottom-up colloidal synthesis of photonic band gap (PBG) materials or photonic crystals (PC) has attracted considerable interest as compared to so-called top-down lithographic approaches due to the simple processing steps involved and the prospect of the economically viable production of complex 3-dimensional optical materials from simple colloidal particles. To date self-assembly techniques constitute the most popular approach to fabricate 3D photonic crystals from colloidal particle suspensions. Based on the natural tendency of monodisperse colloidal particles to organise into ordered arrays, this method represent the best option due to the ease of fabrication, ability to produce larger area samples and cost. Here we report on the fabrication of long range three-dimensional (3D) ordered poly (methyl methacrylate) (PMMA)-silica PC structures and the subsequent fabrication of robust silica inverse opals using self-assembly methods. The optical properties of these materials are described and discussed in terms of potential applications of these materials.


Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1584
Author(s):  
SeongYong Cho ◽  
Masanori Ozaki

Blue phase (BP) liquid crystals, which self-assemble into soft three-dimensional (3D) photonic crystals, have attracted enormous research interest due to their ability to control light and potential photonic applications. BPs have long been known as optically isotropic materials, but recent works have revealed that achieving on-demand 3D orientation of BP crystals is necessary to obtain improved electro-optical performance and tailored optical characteristics. Various approaches have been proposed to precisely manipulate the crystal orientation of BPs on a substrate, through the assistance of external stimuli and directing self-assembly processes. Here, we discuss the various orientation-controlling technologies of BP crystals, with their mechanisms, advantages, drawbacks, and promising applications. This review first focuses on technologies to achieve the uniform crystal plane orientation of BPs on a substrate. Further, we review a strategy to control the azimuthal orientation of BPs along predesigned directions with a uniform crystal plane, allowing the 3D orientation to be uniquely defined on a substrate. The potential applications such as volume holograms are also discussed with their operation principle. This review provides significant advances in 3D photonic crystals and gives a huge potential for intelligent photonic devices with tailored optical characteristics.


2019 ◽  
Vol 75 (3) ◽  
pp. 277-282 ◽  
Author(s):  
Xi Liu ◽  
Bo Fu ◽  
Lin Li ◽  
Yun-Fei Jian ◽  
Si Shu

The assembly of metal–organic frameworks (MOFs) with metal ions and organic ligands is currently attracting considerable attention in crystal engineering and materials science due to their intriguing architectures and potential applications. A new three-dimensional MOF, namely poly[[diaqua(μ8-para-terphenyl-3,3′,5,5′-tetracarboxylato)dizinc(II)] dimethylformamide disolvate monohydrate], {[Zn2(C22H10O8)(H2O)2]·2C3H7NO·H2O} n , was synthesized by the self-assembly of Zn(NO3)2·6H2O and para-terphenyl-3,3′,5,5′-tetracarboxylic acid (H4TPTC) under solvothermal conditions. The compound was structurally characterized by FT–IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. Each ZnII ion is located in a square-pyramidal geometry and is coordinated by four carboxylate O atoms from four different TPTC4− ligands. Pairs of adjacent equivalent ZnII ions are bridged by four carboxylate groups, forming [Zn2(O2CR)4] (R = terphenyl) paddle-wheel units. One aqua ligand binds to each ZnII centre along the paddle-wheel axis. Each [Zn2(O2CR)4] paddle wheel is further linked to four terphenyl connectors to give a three-dimensional framework with NBO-type topology. The thermal stability and solid-state photoluminescence properties of the title compound have also been investigated.


2018 ◽  
Vol 74 (12) ◽  
pp. 1581-1585 ◽  
Author(s):  
Ni-Ya Li ◽  
Dong Liu

The assembly of coordination polymers from metal ions and organic moieties is currently attracting considerable attention in crystal engineering due to their intriguing architectures and potential applications as functional materials. A new coordination polymer, namely poly[[μ2-trans-1,2-bis(pyridin-3-yl)ethylene-κ2 N:N′]bis(μ4-4,4′-oxydibenzoato-κ6 O:O,O′:O′′:O′′,O′′′)dicadmium(II)], [Cd2(C14H8O5)2(C12H10N2)] n or [Cd2(4,4′-OBB)2(3,3′-BPE)] n , has been synthesized by the the self-assembly of Cd(NO3)2·4H2O, 4,4′-oxydibenzoic acid (4,4′-H2OBB) and trans-1,2-bis(pyridin-3-yl)ethene (3,3′-BPE) under hydrothermal conditions. The title compound was structurally characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. Each CdII centre is coordinated by six carboxylate O atoms from four different 4,4′-OBB2− ligands and by one pyridyl N atom form a 3,3′-BPE ligand. Adjacent crystallographically equivalent CdII ions are bridged by 4,4′-OBB2− ligands, affording a two-dimensional [Cd(4,4′-OBB)] n net extending in the ac plane. Neighbouring [Cd(4,4′-OBB)] n nets are interlinked by 3,3′-BPE along the b axis to form a three-dimensional (3D) [Cd2(4,4′-OBB)2(3,3′-BPE)] n coordination network. In the network, each CdII centre is linked by four different 4,4′-OBB2− ligands and one 3,3′-BPE ligand. Meanwhile, each 4,4′-OBB2− ligand connects four separate CdII ions. Therefore, if the 4,4′-OBB2− ligands and CdII ions are considered as 4- and 5-connecting nodes, the structure of the title compound can be simplified as a 3D (4,5)-connected binodal framework with the rare (4462)(4466) TCS topology (Pearson, 1985; Blake et al., 2011). The thermal stability and photoluminescence properties of the title compound have also been investigated.


Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.


2019 ◽  
Vol 10 (45) ◽  
pp. 6116-6121 ◽  
Author(s):  
Tan Ji ◽  
Lei Xia ◽  
Wei Zheng ◽  
Guang-Qiang Yin ◽  
Tao Yue ◽  
...  

We present a new family of porphyrin-functionalized coordination star polymers prepared through combination of coordination-driven self-assembly and post-assembly polymerization. Their self-assembly behaviour in water and potential for photodynamic therapy were demonstrated.


MRS Advances ◽  
2020 ◽  
Vol 5 (64) ◽  
pp. 3507-3520
Author(s):  
Chunhui Dai ◽  
Kriti Agarwal ◽  
Jeong-Hyun Cho

AbstractNanoscale self-assembly, as a technique to transform two-dimensional (2D) planar patterns into three-dimensional (3D) nanoscale architectures, has achieved tremendous success in the past decade. However, an assembly process at nanoscale is easily affected by small unavoidable variations in sample conditions and reaction environment, resulting in a low yield. Recently, in-situ monitored self-assembly based on ion and electron irradiation has stood out as a promising candidate to overcome this limitation. The usage of ion and electron beam allows stress generation and real-time observation simultaneously, which significantly enhances the controllability of self-assembly. This enables the realization of various complex 3D nanostructures with a high yield. The additional dimension of the self-assembled 3D nanostructures opens the possibility to explore novel properties that cannot be demonstrated in 2D planar patterns. Here, we present a rapid review on the recent achievements and challenges in nanoscale self-assembly using electron and ion beam techniques, followed by a discussion of the novel optical properties achieved in the self-assembled 3D nanostructures.


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