WorldWideScience

Sample records for one-dimensional nanostructure effects

  1. One-dimensional nanostructure field-effect sensors for gas detection.

    Science.gov (United States)

    Zhao, Xiaoli; Cai, Bin; Tang, Qingxin; Tong, Yanhong; Liu, Yichun

    2014-07-31

    Recently; one-dimensional (1D) nanostructure field-effect transistors (FETs) have attracted much attention because of their potential application in gas sensing. Micro/nanoscaled field-effect sensors combine the advantages of 1D nanostructures and the characteristic of field modulation. 1D nanostructures provide a large surface area-volume ratio; which is an outstanding advantage for gas sensors with high sensitivity and fast response. In addition; the nature of the single crystals is favorable for the studies of the response mechanism. On the other hand; one main merit of the field-effect sensors is to provide an extra gate electrode to realize the current modulation; so that the sensitivity can be dramatically enhanced by changing the conductivity when operating the sensors in the subthreshold regime. This article reviews the recent developments in the field of 1D nanostructure FET for gas detection. The sensor configuration; the performance as well as their sensing mechanism are evaluated.

  2. One-dimensional nanostructures principles and applications

    CERN Document Server

    Zhai, Tianyou

    2012-01-01

    Reviews the latest research breakthroughs and applications Since the discovery of carbon nanotubes in 1991, one-dimensional nanostructures have been at the forefront of nanotechnology research, promising to provide the building blocks for a new generation of nanoscale electronic and optoelectronic devices. With contributions from 68 leading international experts, this book reviews both the underlying principles as well as the latest discoveries and applications in the field, presenting the state of the technology. Readers will find expert coverage of all major classes of one-di

  3. Giant Peltier Effect in Self-Organized Quasi-One-Dimensional Nano-Structure in Cu-Ni Alloy

    Science.gov (United States)

    Dang Vu, Nguyen; Sato, Kazunori; Katayama-Yoshida, Hiroshi

    2011-01-01

    Based upon ab initio electronic structure calculations by the Korringa-Kohn-Rostoker coherent potential approximation and Monte Carlo simulation of the two-dimensional spinodal nano-decomposition, we simulate the formation of a self-organized quasi-one-dimensional nano-structure (Konbu-Phase) under a layer-by-layer crystal growth condition of Cu-Ni alloy. We propose a new mechanism of the giant Peltier coefficient dramatically enhanced by the one-dimensional singular density of states in the Konbu-Phase in addition to the conventional Peltier cooling and the spin-entropy expansion cooling.

  4. Giant Peltier Effect in Self-Organized Quasi-One-Dimensional Nano-Structure in Cu--Ni Alloy

    Science.gov (United States)

    Vu, Nguyen Dang; Sato, Kazunori; Katayama-Yoshida, Hiroshi

    2011-01-01

    Based upon ab initio electronic structure calculations by the Korringa--Kohn--Rostoker coherent potential approximation and Monte Carlo simulation of the two-dimensional spinodal nano-decomposition, we simulate the formation of a self-organized quasi-one-dimensional nano-structure (Konbu-Phase) under a layer-by-layer crystal growth condition of Cu--Ni alloy. We propose a new mechanism of the giant Peltier coefficient dramatically enhanced by the one-dimensional singular density of states in the Konbu-Phase in addition to the conventional Peltier cooling and the spin-entropy expansion cooling.

  5. Quantum Simulations of One-Dimensional Nanostructures under Arbitrary Deformations

    Science.gov (United States)

    Koskinen, Pekka

    2016-09-01

    A powerful technique is introduced for simulating mechanical and electromechanical properties of one-dimensional nanostructures under arbitrary combinations of bending, twisting, and stretching. The technique is based on an unconventional control of periodic symmetry which eliminates artifacts due to deformation constraints and quantum finite-size effects and allows transparent electronic-structure analysis. Via density-functional tight-binding implementation, the technique demonstrates its utility by predicting nonlinear electromechanical properties in carbon nanotubes and abrupt behavior in the structural yielding of Au7 and Mo6 S6 nanowires. The technique drives simulations markedly closer to the realistic modeling of these slender nanostructures under experimental conditions.

  6. Torsional Detwinning Domino in Nanotwinned One-Dimensional Nanostructures.

    Science.gov (United States)

    Zhou, Haofei; Li, Xiaoyan; Wang, Ying; Liu, Zishun; Yang, Wei; Gao, Huajian

    2015-09-09

    How to maintain sustained deformation in one-dimensional nanostructures without localized failure is an important question for many applications of nanotechnology. Here we report a phenomenon of torsional detwinning domino that leads to giant rotational deformation without localized failure in nanotwinned one-dimensional metallic nanostructures. This mechanism is demonstrated in nanotwinned Cu nanorods via molecular dynamics simulations, where coherent twin boundaries are transformed into twist boundaries and then dissolved one by one, resulting in practically unlimited rotational deformation. This finding represents a fundamental advance in our understanding of deformation mechanisms in one-dimensional metallic nanostructures.

  7. Synthesis of One Dimensional Gold Nanostructures

    Directory of Open Access Journals (Sweden)

    Hongchen Li

    2010-01-01

    Full Text Available Gold nanostructures with shapes of rod, dumbbells, and dog bone have been fabricated by an improved seed-mediated method. It is found that the pH change (the addition of HNO3 or HCl and the presence of Ag+ ions have a great influence on the growth process and aspect ratios of these Au nanocrystals. UV-Vis-NIR absorption spectra for the Au colloidal show that the transverse plasmon absorption band locates at ~520 nm, while the longitudinal plasmon absorption band shifts in a wide spectra region of 750–1100 nm. The obtained Au nanostructures have been investigated by transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray diffractometer. Based on the characterizations and FDTD simulations, most of the obtained Au nanorods are single crystals, possessing an octagonal cross-section bounded by {110} and {100} faces. One model for the anisotropic growth has been proposed. It is found that slow kinetics favor the formation of single-crystalline Au nanorods.

  8. One-dimensional Nanostructured Materials From Organic Precursor

    Institute of Scientific and Technical Information of China (English)

    K. F. Cai

    2005-01-01

    @@ 1Introduction One-dimensional nanostructured materials, such as nanowires, nanobelts, nanotubes and nanocables have been attracting a great research interest in the last decade due to their superior electrical, optical, mechanical and thermal properties, and many methods have been explored to synthesis of the materials, e.g., arc discharge, laser ablation, chemical vapor deposition, thermal evaporation, sol-gel method, template method and so on. In this work, we present a novel and simple method to one-dimensional nanostructured materials by pyrolysis of organic precursor.

  9. One-Dimensional Perovskite Manganite Oxide Nanostructures: Recent Developments in Synthesis, Characterization, Transport Properties, and Applications.

    Science.gov (United States)

    Li, Lei; Liang, Lizhi; Wu, Heng; Zhu, Xinhua

    2016-12-01

    One-dimensional nanostructures, including nanowires, nanorods, nanotubes, nanofibers, and nanobelts, have promising applications in mesoscopic physics and nanoscale devices. In contrast to other nanostructures, one-dimensional nanostructures can provide unique advantages in investigating the size and dimensionality dependence of the materials' physical properties, such as electrical, thermal, and mechanical performances, and in constructing nanoscale electronic and optoelectronic devices. Among the one-dimensional nanostructures, one-dimensional perovskite manganite nanostructures have been received much attention due to their unusual electron transport and magnetic properties, which are indispensable for the applications in microelectronic, magnetic, and spintronic devices. In the past two decades, much effort has been made to synthesize and characterize one-dimensional perovskite manganite nanostructures in the forms of nanorods, nanowires, nanotubes, and nanobelts. Various physical and chemical deposition techniques and growth mechanisms are explored and developed to control the morphology, identical shape, uniform size, crystalline structure, defects, and homogenous stoichiometry of the one-dimensional perovskite manganite nanostructures. This article provides a comprehensive review of the state-of-the-art research activities that focus on the rational synthesis, structural characterization, fundamental properties, and unique applications of one-dimensional perovskite manganite nanostructures in nanotechnology. It begins with the rational synthesis of one-dimensional perovskite manganite nanostructures and then summarizes their structural characterizations. Fundamental physical properties of one-dimensional perovskite manganite nanostructures are also highlighted, and a range of unique applications in information storages, field-effect transistors, and spintronic devices are discussed. Finally, we conclude this review with some perspectives/outlook and future

  10. One-dimensional hybrid nanostructures for heterogeneous photocatalysis and photoelectrocatalysis.

    Science.gov (United States)

    Xiao, Fang-Xing; Miao, Jianwei; Tao, Hua Bing; Hung, Sung-Fu; Wang, Hsin-Yi; Yang, Hong Bin; Chen, Jiazang; Chen, Rong; Liu, Bin

    2015-05-13

    Semiconductor-based photocatalysis and photoelectrocatalysis have received considerable attention as alternative approaches for solar energy harvesting and storage. The photocatalytic or photoelectrocatalytic performance of a semiconductor is closely related to the design of the semiconductor at the nanoscale. Among various nanostructures, one-dimensional (1D) nanostructured photocatalysts and photoelectrodes have attracted increasing interest owing to their unique optical, structural, and electronic advantages. In this article, a comprehensive review of the current research efforts towards the development of 1D semiconductor nanomaterials for heterogeneous photocatalysis and photoelectrocatalysis is provided and, in particular, a discussion of how to overcome the challenges for achieving full potential of 1D nanostructures is presented. It is anticipated that this review will afford enriched information on the rational exploration of the structural and electronic properties of 1D semiconductor nanostructures for achieving more efficient 1D nanostructure-based photocatalysts and photoelectrodes for high-efficiency solar energy conversion.

  11. Effects of temperature and pressure on morphologies of quasi-one-dimensional ZnO nanostructures fabricated via thermal evaporation

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-cheng; CAI Wei; MENG Xiang-long

    2006-01-01

    Quasi one-dimensional zinc oxide nanomaterials were synthesized by thermal evaporation. The structure,morphologies and composition of ZnO nanomaterials prepared under different conditions were studied by XRD,TEM,SEM and EDX. The morphologies are strongly sensitive to the temperature and the pressure during growth,including nanowires,nanobelts,nanocombs and pyramidal-like nanomaterials.

  12. Automated quantification of one-dimensional nanostructure alignment on surfaces

    CERN Document Server

    Dong, Jianjin; Abukhdeir, Nasser Mohieddin

    2016-01-01

    A method for automated quantification of the alignment of one-dimensional nanostructures from microscopy imaging is presented. Nanostructure alignment metrics are formulated and shown to able to rigorously quantify the orientational order of nanostructures within a two-dimensional domain (surface). A complementary image processing method is also presented which enables robust processing of microscopy images where overlapping nanostructures might be present. Scanning electron microscopy (SEM) images of nanowire-covered surfaces are analyzed using the presented methods and it is shown that past single parameter alignment metrics are insufficient for highly aligned domains. Through the use of multiple parameter alignment metrics, automated quantitative analysis of SEM images is shown to be possible and the alignment characteristics of different samples are able to be rigorously compared using a similarity metric. The results of this work provide researchers in nanoscience and nanotechnology with a rigorous metho...

  13. Morphology-Controlled Growth of AIN One-Dimensional Nanostructures

    Institute of Scientific and Technical Information of China (English)

    Ting XIE; Min YE; Xiaosheng FANG; Zhi JIANG; Li CHEN; Mingguang KONG; Yucheng WU; Lide ZHANG

    2008-01-01

    Aluminum nitride (AIN) nanowires, serrated nanoribbons, and nanoribbons were selectively obtained through a simple chloride assisted chemical vapor deposition process. The morphologies of the products could be controlled by adjusting the deposition position and the flux of the reactant gas. The morphologies and structures of the AIN products were investigated in detail. The formation mechanism of the as-prepared different morphologies of AIN one-dimensional (1D) nanostructures was discussed on the basis of the experimental results.

  14. Fabrication and characterization of one dimensional zinc oxide nanostructures

    Science.gov (United States)

    Cheng, Chun

    In this thesis, one dimensional (1D) ZnO nanostructures with controlled morphologies, defects and alignment have been fabricated by a simple vapor transfer method. The crystal structures, interfaces, growth mechanisms and optical properties of ZnO nanostructures have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. Great efforts have been devoted to the patterned growth and assembly of ZnO nanostructures as well as the stability of ZnO nanowires (NWs). Using carbonized photoresists, a simple and very effective method has been developed for fabricating and patterning high-quality ZnO NW arrays. ZnO NWs from this method show excellent alignment, crystal quality, and optical properties that are independent of the substrates. The carbonized photoresists provide perfect nucleation sites for the growth of aligned ZnO NWs and also perfectly connect to the NWs to form ideal electrodes. This approach is further extended to realize large area growth of different forms of ZnO NW arrays (e.g., the horizontal growth and multilayered ZnO NW arrays) on other kinds of carbon-based materials. In addition, the as-synthesized vertically aligned ZnO NW arrays show a low weighted reflectance (Rw) and can be used as antireflection coatings. Moreover, non c-axis growth of 1D ZnO nanostructures (e.g., nanochains, nanobrushes and nanobelts) and defect related 1D ZnO nanostructures (e.g., Y-shaped twinned nanobelts and hierarchical nanostructures decorated by flowers induced by screw dislocations) is also present. Using direct oxidization of pure Zn at high temperatures in air, uniformed ZnO NWs and tetrapods have been fabricated. The spatially-resolved PL study on these two kinds of nanostructures suggests that the defects leading to the green luminescence (GL) should originate from the structural changes along the legs of the tetrapods. Surface defects in these ZnO nanostructures play an unimportant

  15. Solution-phase Synthesis of One-dimensional Semiconductor Nanostructures

    Institute of Scientific and Technical Information of China (English)

    Jianfeng YE; Limin QI

    2008-01-01

    The synthesis of one-dimensional (1D) semiconductor nanostructures has been studied intensively for a wide range of materials due to their unique structural and physical properties and promising potential for future technological applications. Among various strategies for synthesizing 1D semiconductor nanostructures, solution-phase synthetic routes are advantageous in terms of cost, throughput, modulation of composition, and the potential for large-scale and environmentally benign production. This article gives a concise review on the recent developments in the solution-phase synthesis of 1D semiconductor nanostructures of different compositions, sizes, shapes, and architectures. We first introduce several typical solution-phase synthetic routes based on controlled precipitation from homogeneous solutions, including hydrothermal/solvothermal process, solution-liquid-solid (SLS) process, high-temperature organic-solution process, and low-temperature aqueous-solution process. Subsequently, we discuss two solution-phase synthetic strategies involving solid templates or substrates, such as the chemical transformation of 1D sacrificial templates and the oriented growth of 1D nanostructure arrays on solid substrates. Finally, prospects of the solution-phase approaches to 1D semiconductor nanostructures will be briefly discussed.

  16. Automated quantification of one-dimensional nanostructure alignment on surfaces

    Science.gov (United States)

    Dong, Jianjin; Goldthorpe, Irene A.; Mohieddin Abukhdeir, Nasser

    2016-06-01

    A method for automated quantification of the alignment of one-dimensional (1D) nanostructures from microscopy imaging is presented. Nanostructure alignment metrics are formulated and shown to be able to rigorously quantify the orientational order of nanostructures within a two-dimensional domain (surface). A complementary image processing method is also presented which enables robust processing of microscopy images where overlapping nanostructures might be present. Scanning electron microscopy (SEM) images of nanowire-covered surfaces are analyzed using the presented methods and it is shown that past single parameter alignment metrics are insufficient for highly aligned domains. Through the use of multiple parameter alignment metrics, automated quantitative analysis of SEM images is shown to be possible and the alignment characteristics of different samples are able to be quantitatively compared using a similarity metric. The results of this work provide researchers in nanoscience and nanotechnology with a rigorous method for the determination of structure/property relationships, where alignment of 1D nanostructures is significant.

  17. Quantum transport in strongly interacting one-dimensional nanostructures

    NARCIS (Netherlands)

    Agundez, R. R.

    2015-01-01

    In this thesis we study quantum transport in several one-dimensional systems with strong electronic interactions. The first chapter contains an introduction to the concepts treated throughout this thesis, such as the Aharonov-Bohm effect, the Kondo effect, the Fano effect and quantum state transfer.

  18. Stepwise Nanopore Evolution in One-Dimensional Nanostructures

    KAUST Repository

    Choi, Jang Wook

    2010-04-14

    We report that established simple lithium (Li) ion battery cycles can be used to produce nanopores inside various useful one-dimensional (1D) nanostructures such as zinc oxide, silicon, and silver nanowires. Moreover, porosities of these 1D nanomaterials can be controlled in a stepwise manner by the number of Li-battery cycles. Subsequent pore characterization at the end of each cycle allows us to obtain detailed snapshots of the distinct pore evolution properties in each material due to their different atomic diffusion rates and types of chemical bonds. Also, this stepwise characterization led us to the first observation of pore size increases during cycling, which can be interpreted as a similar phenomenon to Ostwald ripening in analogous nanoparticle cases. Finally, we take advantage of the unique combination of nanoporosity and 1D materials and demonstrate nanoporous silicon nanowires (poSiNWs) as excellent supercapacitor (SC) electrodes in high power operations compared to existing devices with activated carbon. © 2010 American Chemical Society.

  19. One-Dimensional Nanostructures and Devices of II–V Group Semiconductors

    Directory of Open Access Journals (Sweden)

    Shen Guozhen

    2009-01-01

    Full Text Available Abstract The II–V group semiconductors, with narrow band gaps, are important materials with many applications in infrared detectors, lasers, solar cells, ultrasonic multipliers, and Hall generators. Since the first report on trumpet-like Zn3P2nanowires, one-dimensional (1-D nanostructures of II–V group semiconductors have attracted great research attention recently because these special 1-D nanostructures may find applications in fabricating new electronic and optoelectronic nanoscale devices. This article covers the 1-D II–V semiconducting nanostructures that have been synthesized till now, focusing on nanotubes, nanowires, nanobelts, and special nanostructures like heterostructured nanowires. Novel electronic and optoelectronic devices built on 1-D II–V semiconducting nanostructures will also be discussed, which include metal–insulator-semiconductor field-effect transistors, metal-semiconductor field-effect transistors, andp–nheterojunction photodiode. We intent to provide the readers a brief account of these exciting research activities.

  20. Filtration-guided assembly for patterning one-dimensional nanostructures

    Science.gov (United States)

    Zhang, Yaozhong; Wang, Chuan; Yeom, Junghoon

    2017-04-01

    Tremendous progress has been made in synthesizing various types of one-dimensional (1D) nanostructures (NSs), such as nanotubes and nanowires, but some technical challenges still remain in the deterministic assembly of the solution-processed 1D NSs for device integration. In this work we investigate a scalable yet inexpensive nanomaterial assembly method, namely filtration-guided assembly (FGA), to place nanomaterials into desired locations as either an individual entity or ensembles, and form functional devices. FGA not only addresses the assembly challenges but also encompasses the notion of green nanomanufacturing, maximally utilizing nanomaterials and eliminating a waste stream of nanomaterials into the environment. FGA utilizes selective filtration of 1D NSs through the open windows on the nanoporous filter membrane whose surface is patterned by a polymer mask for guiding the 1D NS deposition. The modified soft-lithographic technique called blanket transfer (BT) is employed to create the various photoresist patterns of sub-10-micron resolution on the nanoporous filter membrane like mixed cellulose acetate. We use single-walled carbon nanotubes (SWCNTs) as a model 1D NS and demonstrate the fabrication of an array pattern of homogeneous 1D NS network films over an area of 20 cm2 within 10 min. The FGA-patterned SWCNT network films are transferred onto the substrate using the adhesive-based transfer technique, and show the highly uniform film thickness and resistance measurements across the entire substrate. Finally, the electrical performance of the back-gated transistors made from the FGA and transfer method of 95% pure SWCNTs is demonstrated.

  1. Preparation of one-dimensional nanostructured ZnO

    Institute of Scientific and Technical Information of China (English)

    Xiuping Jiang; Youzhi Liu; Yanyang Cao; Xuejun Zhang; Lihong Shi

    2010-01-01

    Rod-like ZnO particles were synthesized via a sol-gel method by adding ethylene diamine(EDA)to the were characterized by XRD(X-ray powder diffractometer)and TEM(transmission electron microscope).Rod-like ZnO belongs to the hexagonal Wurtzite system,with diameters and lengths of about 20-200nm and 0.2-1.5μm,respectively.Experimental results showed that the morphology of nano-ZnO can be controlled by modulating the quantities of EDA added into the reaction system and that EDA plays an important role in the formation of rod-like ZnO particles.The growth mechanism of the rod-like nano-ZnO was briefly discussed.The proposed facile,reproducible,effective and low-cost synthesis promises future large-scale preparation of nanostructured ZnO for application in nanotechnology.

  2. A Comprehensive Review of One-Dimensional Metal-Oxide Nanostructure Photodetectors

    Directory of Open Access Journals (Sweden)

    Bando Yoshio

    2009-08-01

    Full Text Available One-dimensional (1D metal-oxide nanostructures are ideal systems for exploring a large number of novel phenomena at the nanoscale and investigating size and dimensionality dependence of nanostructure properties for potential applications. The construction and integration of photodetectors or optical switches based on such nanostructures with tailored geometries have rapidly advanced in recent years. Active 1D nanostructure photodetector elements can be configured either as resistors whose conductions are altered by a charge-transfer process or as field-effect transistors (FET whose properties can be controlled by applying appropriate potentials onto the gates. Functionalizing the structure surfaces offers another avenue for expanding the sensor capabilities. This article provides a comprehensive review on the state-of-the-art research activities in the photodetector field. It mainly focuses on the metal oxide 1D nanostructures such as ZnO, SnO2, Cu2O, Ga2O3, Fe2O3, In2O3, CdO, CeO2, and their photoresponses. The review begins with a survey of quasi 1D metal-oxide semiconductor nanostructures and the photodetector principle, then shows the recent progresses on several kinds of important metal-oxide nanostructures and their photoresponses and briefly presents some additional prospective metal-oxide 1D nanomaterials. Finally, the review is concluded with some perspectives and outlook on the future developments in this area.

  3. A combined experimental and theoretical approach towards the understanding of transport in one-dimensional molecular nanostructures

    OpenAIRE

    Grimm, Daniel

    2008-01-01

    This thesis comprises detailed experimental and theoretical investigations of the transport properties of one-dimensional nanostructures. Most of the work is dedicated to the exploration of the fascinating effects occurring in single wall carbon nanotubes (SWCNT). These particular nanostructures gained an overwhelming interest in the past two decades due to its outstanding electronic and mechanical features. We have investigated the properties of a novel family of carbon nanostructures, named...

  4. Localized surface plasmon of quasi-one-dimensional metallic nanostructures

    Science.gov (United States)

    Liu, Mingzhao

    2007-05-01

    The plasmon resonance of noble metal nanoparticles provides interesting optical properties in the visible and near-infrared region, and is highly tunable by varying the shape and the composition of the nanoparticles. The rod-like gold nanostructures can be synthesized by a seed-mediated method in aqueous surfactant solutions. Starting from different types of gold seeds, either single crystalline gold nanorods or penta-fold twinned gold bipyramids can be synthesized in decent yield with silver(I) added into the growth solution. These nanostructures have pronounced plasmon resonance varying in the 1˜2 eV range. The bipyramids are strikingly monodisperse in shape, which leads to the sharpest ensemble longitudinal plasmon resonance reported so far for metal colloid solutions. A mechanism based on the underpotential deposition of silver was thus suggested to explain the essential role of Ag(I) in the growth process. The optical spectra of the gold colloids were simulated with the finite-difference time-domain (FDTD) method. The results show excellent agreement with recent experimental optical spectra. The local field enhancement (|E|/|E0|) was studied at the plasmon resonance. Sharper structural features produce more significant enhancement and the largest enhancement of more than a factor of 200 is seen around the poles of the bipyramid. A large internal field enhancement by more than a factor of 30 is found for the bipyramids, which suggests that they will exhibit very strong optical nonlinearities. The plasmon can be further tuned by introducing the core/shell nanostructures such as metal/metal or metal/semiconductor nanorods. Following a simple procedure, a homogeneous layer of silver with 1-4 nm thickness can be plated onto the gold nanorods, which shifts the longitudinal plasmon mode of the nanorods toward blue. The silver layer can be converted to semiconductors silver sulfide or selenide, with the longitudinal plasmon resonance tuned toward red. The metal

  5. One-dimensional CdS nanostructures: synthesis, properties, and applications

    Science.gov (United States)

    Zhai, Tianyou; Fang, Xiaosheng; Li, Liang; Bando, Yoshio; Golberg, Dmitri

    2010-02-01

    One-dimensional (1D) semiconductor nanostructures are of prime interest due to their potential in investigating the size and dimensionality dependence of the materials' physical properties and constructing nanoscale electronic and optoelectronic devices. Cadmium sulfide (CdS) is an important semiconductor compound of the ii-vi group, and its synthesis and properties have been of growing interest owing to prominent applications in several fields. This article provides a comprehensive review of the state-of-the-art research activities that focus on the rational synthesis, novel properties and unique applications of 1D CdS nanostructures in nanotechnology. It begins with the rational design and synthesis of 1D CdS nanostructures, and then highlights a range of unique properties and applications (e.g. photoluminescence, cathodoluminescence, electrochemiluminescence, photocatalysis, lasers, waveguides, modulators, solar cells, field-effect transistors, photodetectors, field-emitters, and nanogenerators) associated with them. Finally, the review is concluded with the author outlook of the perspectives with respect to future research on 1D CdS nanostructures.

  6. CONTROLLED FABRICATION OF ONE-DIMENSIONAL POLYMER NANOSTRUCTURES via METALLOGEL TEMPLATE POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Lu Qiang; Li-ming Tang; Bo-tian Li; Kai Chen

    2012-01-01

    A facile method is reported to controllably fabricate one dimensional (1D) polymer nanostructures via metallogel template polymerization.The metallogel was prepared through coordination interactions between silver ions and a ligand (L) bearing three pyridyl groups in tetrahydrofuran (THF).The diameters of the metallogel nanofibers could be tuned by the gel concentration (GC).Due to its high thermal stability and facility of removal,the metallogel was used as the template for radical polymerization of diacryolyl-2,6-diaminopyridine (DADAP) to form poly-diacryolyl-2,6-diaminopyridine (PDADAP) nanostructures.The gradually eroding of the templates by PDADAP provided us an effective way to fabricate various nanostructures of the polymer.We have demonstrated that different 1D nanostructures,including nanoribbons,nanotubes and nanowires,could be selectively fabricated by adjusting polymerization time,monomer concentration and GC.The rheological properties of the gel samples were tested by a rheometer.As prolonging the reaction time,more and more polymers were formed and the strength of the resulting polymer gels became higher and higher.The simple preparation process,easy controlled microstructures and adequate gel strength would make it a facile synthetic method for different 1D polymer nanosturctures.

  7. High Speed Water Sterilization Using One-Dimensional Nanostructures

    KAUST Repository

    Schoen, David T.

    2010-09-08

    The removal of bacteria and other organisms from water is an extremely important process, not only for drinking and sanitation but also industrially as biofouling is a commonplace and serious problem. We here present a textile based multiscale device for the high speed electrical sterilization of water using silver nanowires, carbon nanotubes, and cotton. This approach, which combines several materials spanning three very different length scales with simple dying based fabrication, makes a gravity fed device operating at 100000 L/(h m2) which can inactivate >98% of bacteria with only several seconds of total incubation time. This excellent performance is enabled by the use of an electrical mechanism rather than size exclusion, while the very high surface area of the device coupled with large electric field concentrations near the silver nanowire tips allows for effective bacterial inactivation. © 2010 American Chemical Society.

  8. Synthesis and Application of One-Dimensional La(OH)3 Nanostructures: An Overview

    OpenAIRE

    Xiang Xiao; Yu Huang; Fan Dong

    2014-01-01

    One-dimensional (1D) semiconductor nanomaterials are of particular importance owing to their unique properties and potential applications. This review attempts to provide a comprehensive introduction of 1D La(OH)3 nanostructures including nanowires, nanoneedles, nanobelts, and nanorods. Firstly, various strategies developed to fabricate the 1D La(OH)3 nanostructures are discussed, such as precipitation and composite-hydroxide-mediated, hydrothermal, and solvothermal methods, accompanying the ...

  9. Recent Progress in One-dimensional ZnS Nanostructures:Syntheses and Novel Properties

    Institute of Scientific and Technical Information of China (English)

    Xiaosheng FANG; Yoshio BANDO; Dmitri GOLBERG

    2008-01-01

    In this review, the progress made during the last two years with respect to the syntheses and novel properties of one-dimensional (1D) ZnS nanostructures is presented. Primarily the research on 1D ZnS nanostructures has been of growing interest owing to their promising applications in nanoscale optoelectronic devices. Diverse 1D ZnS nanostructures with delicately-tuned morphologies, sizes, and microstructures have been synthesized through relatively simple and well-controlled techniques. Some novel properties of the nanomaterials have been explored and the relationships between their structural features and functions have been understood gradually.

  10. One-dimensional CdS nanostructures: a promising candidate for optoelectronics.

    Science.gov (United States)

    Li, Huiqiao; Wang, Xi; Xu, Junqi; Zhang, Qi; Bando, Yoshio; Golberg, Dmitri; Ma, Ying; Zhai, Tianyou

    2013-06-11

    As a promising candidate for optoelectronics, one-dimensional CdS nanostructures have drawn great scientific and technical interest due to their interesting fundamental properties and possibilities of utilization in novel promising optoelectronical devices with augmented performance and functionalities. This progress report highlights a selection of important topics pertinent to optoelectronical applications of one-dimensional CdS nanostructures over the last five years. This article begins with the description of rational design and controlled synthesis of CdS nanostructure arrays, alloyed nanostructucures and kinked nanowire superstructures, and then focuses on the optoelectronical properties, and applications including cathodoluminescence, lasers, light-emitting diodes, waveguides, field emitters, logic circuits, memory devices, photodetectors, gas sensors, photovoltaics and photoelectrochemistry. Finally, the general challenges and the potential future directions of this exciting area of research are highlighted.

  11. Template-free Synthesis of One-dimensional Cobalt Nanostructures by Hydrazine Reduction Route

    Directory of Open Access Journals (Sweden)

    Lan Tianmin

    2011-01-01

    Full Text Available Abstract One-dimensional cobalt nanostructures with large aspect ratio up to 450 have been prepared via a template-free hydrazine reduction route under external magnetic field assistance. The morphology and properties of cobalt nanostructures were characterized by scanning electron microscopy, X-ray diffractometer, and vibrating sample magnetometer. The roles of the reaction conditions such as temperature, concentration, and pH value on morphology and magnetic properties of fabricated Co nanostructures were investigated. This work presents a simple, low-cost, environment-friendly, and large-scale production approach to fabricate one-dimensional magnetic Co materials. The resulting materials may have potential applications in nanodevice, catalytic agent, and magnetic recording.

  12. Facile Synthesis and Tensile Behavior of TiO2 One-Dimensional Nanostructures

    Directory of Open Access Journals (Sweden)

    Li Shu-you

    2009-01-01

    Full Text Available Abstract High-yield synthesis of TiO2 one-dimensional (1D nanostructures was realized by a simple annealing of Ni-coated Ti grids in an argon atmosphere at 950 °C and 760 torr. The as-synthesized 1D nanostructures were single crystalline rutile TiO2 with the preferred growth direction close to [210]. The growth of these nanostructures was enhanced by using catalytic materials, higher reaction temperature, and longer reaction time. Nanoscale tensile testing performed on individual 1D nanostructures showed that the nanostructures appeared to fracture in a brittle manner. The measured Young’s modulus and fracture strength are ~56.3 and 1.4 GPa, respectively.

  13. One-dimensional carbon nanostructures for terahertz electron-beam radiation

    Science.gov (United States)

    Tantiwanichapan, Khwanchai; Swan, Anna K.; Paiella, Roberto

    2016-06-01

    One-dimensional carbon nanostructures such as nanotubes and nanoribbons can feature near-ballistic electronic transport over micron-scale distances even at room temperature. As a result, these materials provide a uniquely suited solid-state platform for radiation mechanisms that so far have been the exclusive domain of electron beams in vacuum. Here we consider the generation of terahertz light based on two such mechanisms, namely, the emission of cyclotronlike radiation in a sinusoidally corrugated nanowire (where periodic angular motion is produced by the mechanical corrugation rather than an externally applied magnetic field), and the Smith-Purcell effect in a rectilinear nanowire over a dielectric grating. In both cases, the radiation properties of the individual charge carriers are investigated via full-wave electrodynamic simulations, including dephasing effects caused by carrier collisions. The overall light output is then computed with a standard model of charge transport for two particularly suitable types of carbon nanostructures, i.e., zigzag graphene nanoribbons and armchair single-wall nanotubes. Relatively sharp emission peaks at geometrically tunable terahertz frequencies are obtained in each case. The corresponding output powers are experimentally accessible even with individual nanowires, and can be scaled to technologically significant levels using array configurations. These radiation mechanisms therefore represent a promising paradigm for light emission in condensed matter, which may find important applications in nanoelectronics and terahertz photonics.

  14. Quasi-one dimensional (Q1D) nanostructures: Synthesis, integration and device application

    Science.gov (United States)

    Chien, Chung-Jen

    Quasi-one-dimensional (Q1D) nanostructures such as nanotubes and nanowires have been widely regarded as the potential building blocks for nanoscale electronic, optoelectronic and sensing devices. In this work, the content can be divided into three categories: Nano-material synthesis and characterizations, alignment and integration, physical properties and application. The dissertation consists of seven chapters as following. Chapter 1 will give an introduction to low dimensional nano-materials. Chapter 2 explains the mechanism how Q1D nanostructure grows. Chapter 3 describes the methods how we horizontally and vertically align the Q1D nanostructure. Chapter 4 and 5 are the electrical and optical device characterization respectively. Chapter 6 demonstrates the integration of Q1D nanostructures and the device application. The last chapter will discuss the future work and conclusion of the thesis.

  15. One Dimensional Nanostructures for Lithium-ion Batteries, Gas Sensors and Optoelectronics Applications

    Institute of Scientific and Technical Information of China (English)

    G.X.Wang; M.S.Park; J.S.Park; X.L.Gou; J.Yang; D.Wexler; J.Z.Wang; J.Yao; H.K.Liu

    2007-01-01

    1 Results One dimensional (1D) nanostructures such as nanowires,nanotubes,nanorods and nanoribbons have been extensively investigated for a wide range of applications[1].Here,we present the synthesis,characterization and technological applications of several 1D nanostructures including SnO2 nanowires,CuO nanoribbons,CdSe nanowires and In2O3 nanowires.SnO2 nanowires were synthesized by thermal evaporation combined with a self-catalyzed growth procedure.Scanning electron microscopy (SEM) observation shows...

  16. Preparation of TiO2 one-dimensional nanostructures: The effect of oxidizing solvent on structural properties and photocatalytic activity

    Science.gov (United States)

    Ramezani Sani, S.; Mohseni, F.; Javid, M.; Mortezaali, A.

    2016-10-01

    TiO2 nanowires were prepared by hydrothermal growth on Ti plates at 180°C with acetone solvent to oxidize Ti. The effect of the acetone concentration on the structural properties and photocatalytic activity was carefully investigated. It was found that a lower concentration of the oxidizing solvent leads to thinner and longer nanowires. The relationship between the percent of degradation of Methyl Orange (MO) and acetone concentration showed that with increasing acetone concentration, the percent of degradation of MO decreased due to decrease in the content of oxygen vacancies. Photocatalytic reactions at the different acetone concentration all followed the pseudo-first-order rate law. The rate constants increased with decreasing acetone concentration.

  17. One-dimensional titania nanostructures: Synthesis and applications in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Guo, Zhiguang, E-mail: zguo@licp.cas.cn [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Shimin [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials, Hubei University, Wuhan 430062 (China); Liu, Weimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2014-05-02

    One-dimensional (1D) titania (TiO{sub 2}) in the form of nanorods, nanowires, nanobelts and nanotubes have attracted much attention due to their unique physical, chemical and optical properties enabling extraordinary performance in biomedicine, sensors, energy storage, solar cells and photocatalysis. In this review, we mainly focus on synthetic methods for 1D TiO{sub 2} nanostructures and the applications of 1D TiO{sub 2} nanostructures in dye-sensitized solar cells (DSCs). Traditional nanoparticle-based DSCs have numerous grain boundaries and surface defects, which increase the charge recombination from photoanode to electrolyte. 1D TiO{sub 2} nanostructures can provide direct and rapid electron transport to the electron collecting electrode, indicating a promising choice for DSCs. We divide the applications of 1D TiO{sub 2} nanostructures in DSCs into four parts, that is, 1D TiO{sub 2} nanostructures only, 1D TiO{sub 2} nanostructure/nanoparticle composites, branched 1D TiO{sub 2} nanostructures, and 1D TiO{sub 2} nanostructures combined with other materials. This work will provide guidance for preparing 1D TiO{sub 2} nanostructures, and using them as photoanodes in efficient DSCs. - Graphical abstract: 1D TiO{sub 2} nanostructures which can provide direct and rapid pathways for electron transport have promising applications in dye-sensitized solar cells (DSCs). The synthetic methods and applications of 1D TiO{sub 2} nanostructures in DSCs are summarized in this review article.

  18. One-Dimensional (1D) ZnS Nanomaterials and Nanostructures

    Institute of Scientific and Technical Information of China (English)

    Xiaosheng FANG; Lide ZHANG

    2006-01-01

    One-dimensional (1D) nanomaterials and nanostructures have received much attention due to their potential interest for understanding fundamental physical concepts and for applications in constructing nanoscale electric and optoelectronic devices. Zinc sulfide (ZnS) is an important semiconductor compound of Ⅱ-Ⅵ group,and the synthesis of 1D ZnS nanomaterials and nanostructures has been of growing interest owing to their promising application in nanoscale optoelectronic devices. This paper reviews the recent progress on 1D ZnS nanomaterials and nanostructures, including nanowires, nanowire arrays, nanorods, nanobelts or nanoribbons,nanocables, and hierarchical nanostructures etc. This article begins with a survey of various methods that have been developed for generating 1D nanomaterials and nanostructures, and then mainly focuses on structures,synthesis, characterization, formation mechanisms and optical property tuning, and luminescence mechanisms of 1D ZnS nanomaterials and nanostructures. Finally, this review concludes with personal views towards future research on 1D ZnS nanomaterials and nanostructures.

  19. Synthesis and Application of One-Dimensional La(OH3 Nanostructures: An Overview

    Directory of Open Access Journals (Sweden)

    Xiang Xiao

    2014-01-01

    Full Text Available One-dimensional (1D semiconductor nanomaterials are of particular importance owing to their unique properties and potential applications. This review attempts to provide a comprehensive introduction of 1D La(OH3 nanostructures including nanowires, nanoneedles, nanobelts, and nanorods. Firstly, various strategies developed to fabricate the 1D La(OH3 nanostructures are discussed, such as precipitation and composite-hydroxide-mediated, hydrothermal, and solvothermal methods, accompanying the description of the corresponding growth mechanisms. Then, the unique properties such as novel physical properties of 1D La(OH3 nanostructures resulting from their unique electronic structures and numerous transition modes involving the 4f shells of these ions are represented in detail. Also, the wide applications in photocatalyst, capacitors, and photoluminescence based on the unique properties are discussed. Finally, the paper ends with a summary and some perspectives on the challenges and new directions in this emerging area.

  20. Controlled fabrication of fullerene derivative one-dimensional nanostructures via electrophoretic deposition of its clusters

    Institute of Scientific and Technical Information of China (English)

    GUO Yuguo; WAN Lijun; WANG Chunru; BAI Chunli; GAN Liangbing; CHEN Dongmin

    2004-01-01

    Well-defined and controllable one-dimensional (1D) nanostructures of fullerene derivative have been prepared by an electrophoretic template synthesis method. The clusters of fullerene derivative formed in mixed solvents are introduced into the channels of porous alumina templates through a dc electric field. Four types of 1D nanostructures (solid nanowires, solid-wall nanotubes, porous nanowires and porous-wall nanotubes) have been obtained by changing the deposition parameters. This approach opens a new avenue to assemble fullerene derivatives, endohedral fullerenes, as well as other functional organic compounds, which can form clusters in 1D nanostructure arrays for applications in chemical sensors, light energy conversion devices and nanoscale electronic and optoelectronic devices.

  1. One-dimensional ZnS-based Hetero-, Core/shell and Hierarchical Nanostructures

    Institute of Scientific and Technical Information of China (English)

    Xiaosheng FANG; Ujjal K.Gautam; Yoshio BANDO; Dmitri GOLBERG

    2008-01-01

    A focus of the current nanotechnology has shifted from routine fabrication of nanostructures to designing functional electronic devices and realizing their immense potentials for applications. Due to infusion of multifunctionality into a single system, the utilization of hetero-, core/shell and hierarchical nanostructures has become the key issue for building such devices. ZnS, due to its direct wide bandgap, high index of refraction, high transparency in the visible range and intrinsic polarity, is one of the most useful semiconductors for a wide range of electronics applications. This article provides a dense review of the state-of-the-art research activities in one-dimensional (1D) ZnS-based hetero-, core/shell and hierarchical nanostructures. The particular emphasis is put on their syntheses and applications.

  2. One-Dimensional Nanostructured TiO2 for Photocatalytic Degradation of Organic Pollutants in Wastewater

    Directory of Open Access Journals (Sweden)

    Ting Feng

    2014-01-01

    Full Text Available The present paper reviews the progress in the synthesis of one-dimensional (1D TiO2 nanostructures and their environmental applications in the removal of organic pollutants. According to the shape, 1D TiO2 nanostructures can be divided into nanorods, nanotubes, nanowires/nanofibers, and nanobelts. Each of them can be synthesized via different technologies, such as sol-gel template method, chemical vapor deposition, and hydrothermal method. These methods are discussed in this paper, and the recent development of the synthesis technologies is also presented. Furthermore, the organic pollutants, degradation using the synthesized 1D TiO2 nanostructures is studied as an important application of photocatalytic oxidation (PCO. The 1D nanostructured TiO2 exhibited excellent photocatalytic activity in a PCO process, and the mechanism of photocatalytic degradation of organic pollutants is also discussed. Moreover, the modification of 1D TiO2 nanostructures using metal ions, metal oxide, or inorganic element can further enhance the photocatalytic activity of the photocatalyst. This phenomenon can be explained by the suppression of e−-h+ pairs recombination rate, increased specific surface area, and reduction of band gap. In addition, 1D nanostructured TiO2 can be further constructed as a film or membrane, which may extend its practical applications.

  3. One-Dimensional SnO2 Nanostructures: Synthesis and Applications

    Directory of Open Access Journals (Sweden)

    Jun Pan

    2012-01-01

    Full Text Available Nanoscale semiconducting materials such as quantum dots (0-dimensional and one-dimensional (1D structures, like nanowires, nanobelts, and nanotubes, have gained tremendous attention within the past decade. Among the variety of 1D nanostructures, tin oxide (SnO2 semiconducting nanostructures are particularly interesting because of their promising applications in optoelectronic and electronic devices due to both good conductivity and transparence in the visible region. This article provides a comprehensive review of the recent research activities that focus on the rational synthesis and unique applications of 1D SnO2 nanostructures and their optical and electrical properties. We begin with the rational design and synthesis of 1D SnO2 nanostructures, such as nanotubes, nanowires, nanobelts, and some heterogeneous nanostructures, and then highlight a range of applications (e.g., gas sensor, lithium-ion batteries, and nanophotonics associated with them. Finally, the review is concluded with some perspectives with respect to future research on 1D SnO2 nanostructures.

  4. Tunable self-assembly of one-dimensional nanostructures with orthogonal directions

    Directory of Open Access Journals (Sweden)

    Allan Milan

    2007-01-01

    Full Text Available AbstractHigh-temperature exposure of a Mo(110 surface to borazine (HBNH3leads to the formation of two distinctly different self-assembling nanostructures. Depending on the substrate temperature during preparation, either well-aligned, ultra-thin boron nanowires or a single-layer stripe structure of hexagonal boron nitride forms. Both structures show one-dimensional (1D characteristics, but in directions perpendicular to each other. It is also possible to grow the two phases in coexistence. The relative weights are controlled by the sample temperature during preparation.

  5. Synthesis of One-Dimensional SiC Nanostructures from a Glassy Buckypaper

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Mengning; Star, Alexander

    2013-02-21

    A simple and scalable synthetic strategy was developed for the fabrication of one-dimensional SiC nanostructures - nanorods and nanowires. Thin sheets of single-walled carbon nanotubes (SWNTs) were prepared by vacuum filtration and were washed repeatedly with sodium silicate (Na₂SiO₃) solution. The resulting “glassy buckypaper” was heated at 1300 - 1500 °C under Ar/H₂ to allow a solid state reaction between C and Si precursors to form a variety of SiC nanostructures. The morphology and crystal structures of SiC nanorods and nanowires were characterized using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive xray spectroscopy (EDX), electron diffraction (ED) and x-ray diffraction (XRD) techniques. Furthermore, electrical conductance measurements were performed on SiC nanorods, demonstrating their potential applications in high-temperature sensors and control systems.

  6. Gas Sensors Based on One Dimensional Nanostructured Metal-Oxides: A Review

    Directory of Open Access Journals (Sweden)

    A. S. M. A. Haseeb

    2012-05-01

    Full Text Available Recently one dimensional (1-D nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO2, TiO2, In2O3, WOx, AgVO3, CdO, MoO3, CuO, TeO2 and Fe2O3. Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research.

  7. Gas sensors based on one dimensional nanostructured metal-oxides: a review.

    Science.gov (United States)

    Arafat, M M; Dinan, B; Akbar, Sheikh A; Haseeb, A S M A

    2012-01-01

    Recently one dimensional (1-D) nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO(2), TiO(2), In(2)O(3), WO(x), AgVO(3), CdO, MoO(3), CuO, TeO(2) and Fe(2)O(3). Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research.

  8. A Comprehensive Review of Semiconductor Ultraviolet Photodetectors: From Thin Film to One-Dimensional Nanostructures

    Directory of Open Access Journals (Sweden)

    Liwen Sang

    2013-08-01

    Full Text Available Ultraviolet (UV photodetectors have drawn extensive attention owing to their applications in industrial, environmental and even biological fields. Compared to UV-enhanced Si photodetectors, a new generation of wide bandgap semiconductors, such as (Al, In GaN, diamond, and SiC, have the advantages of high responsivity, high thermal stability, robust radiation hardness and high response speed. On the other hand, one-dimensional (1D nanostructure semiconductors with a wide bandgap, such as β-Ga2O3, GaN, ZnO, or other metal-oxide nanostructures, also show their potential for high-efficiency UV photodetection. In some cases such as flame detection, high-temperature thermally stable detectors with high performance are required. This article provides a comprehensive review on the state-of-the-art research activities in the UV photodetection field, including not only semiconductor thin films, but also 1D nanostructured materials, which are attracting more and more attention in the detection field. A special focus is given on the thermal stability of the developed devices, which is one of the key characteristics for the real applications.

  9. Controlled synthesis and energy applications of one-dimensional conducting polymer nanostructures: an overview

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Zhigang; Zheng, Qingdong [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian (China)

    2012-02-15

    The past decade has witnessed increasing attention in the synthesis, properties, and applications of one-dimensional (1D) conducting polymer nanostructures. This overview first summarizes the synthetic strategies for various 1D nanostructures of conjugated polypyrrole (PPy), polyaniline (PANI), polythiophene (PTh), poly(p-phenylenevinylene) (PPV) and derivatives thereof. By using template-directed or template-free methods, nanoscale rods, wires/fibers, belts/ribbons, tubes, arrays, or composites have been successfully synthesized. With their unique structures and advantageous characteristics (e.g., high conductivity, high carrier mobility, good electrochemical activity, large specific surface area, short and direct path for charge/ion transportation, good mechanical properties), 1D conducting polymer nanostructures are demonstrated to be very useful for energy applications. Next, their applications in solar cells, fuel cells, rechargeable lithium batteries, and electrochemical supercapacitors are highlighted, with a strong emphasis on recent literature examples. Finally, this review ends with a summary and some perspectives on the challenges and opportunities in this emerging area of research. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy

    Science.gov (United States)

    Lee, Jung Ah; Rok Lim, Young; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

    2016-10-01

    To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes.

  11. Structural characterization of one-dimensional ZnO-based nanostructures grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Sallet, Vincent; Falyouni, Farid; Marzouki, Ali; Haneche, Nadia; Sartel, Corinne; Lusson, Alain; Galtier, Pierre [Groupe d' Etude de la Matiere Condensee (GEMAC), CNRS-Universite de Versailles St-Quentin, Meudon (France); Agouram, Said [SCSIE, Universitat de Valencia, Burjassot (Spain); Enouz-Vedrenne, Shaima [Thales Research and Technology France, Palaiseau (France); Munoz-Sanjose, Vicente [Departamento de Fisica Aplicada y Electromagnetismo, Universitat de Valencia, Burjassot (Spain)

    2010-07-15

    Various one-dimensional (1D) ZnO-based nanostructures, including ZnO nano-wires (NWs) grown using vapour-liquid-solid (VLS) process, ZnO/ZnSe core/shell, nitrogen-doped ZnO and ZnMgO NWs were grown by metalorganic chemical vapour deposition (MOCVD). Transmission electron microscopy (TEM) analysis is presented. For all the samples, a high crystalline quality is observed. Some features are emphasized such as the gold contamination of ZnO wires grown under the metal droplets in the VLS process. It is concluded that MOCVD is a suitable technique for the realization of original ZnO nanodevices. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  12. One-Dimensional Metal-Oxide Nanostructures for Solar Photocatalytic Water-Splitting

    Science.gov (United States)

    Wang, Fengyun; Song, Longfei; Zhang, Hongchao; Luo, Linqu; Wang, Dong; Tang, Jie

    2017-08-01

    Because of their unique physical and chemical properties, one-dimensional (1-D) metal-oxide nanostructures have been extensively applied in the areas of gas sensors, electrochromic devices, nanogenerators, and so on. Solar water-splitting has attracted extensive research interest because hydrogen generated from solar-driven water splitting is a clean, sustainable, and abundant energy source that not only solves the energy crisis, but also protects the environment. In this comprehensive review, the main synthesis methods, properties, and especially prominent applications in solar water splitting of 1-D metal-oxides, including titanium dioxide (TiO2), zinc oxide (ZnO), tungsten trioxide (WO3), iron oxide (Fe2O3), and copper oxide (CuO) are fully discussed.

  13. Exploring arrays of vertical one-dimensional nanostructures for cellular investigations

    DEFF Research Database (Denmark)

    Bonde, Sara; Buch-Månson, Nina; Rostgaard, Katrine Rønne;

    2014-01-01

    The endeavor of exploiting arrays of vertical one-dimensional (1D) nanostructures (NSs) for cellular applications has recently been experiencing a pronounced surge of activity. The interest is rooted in the intrinsic properties of high-aspect-ratio NSs. With a height comparable to a mammalian cell...... of research. Encouragingly, despite the diversity of NS platforms and experimental conditions used thus far, general trends and conclusions from combining cells with NSs are beginning to crystallize. This review covers the broad spectrum of NS materials and dimensions used; the observed cellular responses....... By maintaining the impressive rate and quality of recent progress, it is conceivable that the use of vertical 1D NSs may soon be established as a superior choice over other current techniques, with all the further benefits that may entail. © 2014 IOP Publishing Ltd....

  14. One-dimensional chiral copper (II) complexes with novel nano-structures and superior antitumor activity.

    Science.gov (United States)

    Zhang, Wei Chuan; Tang, Xue; Lu, Xiaoming

    2016-03-01

    Three novel copper(II) compounds of formulas {[Cu(Phen)(Ala)]·NO3·H2O}n (1), {[Cu(Phen)(Ala)]·NO3}n (2) and [Cu(Ala)2]n (3) have been synthesized and determined by X-ray diffraction. 1 and 2 are shown in one dimensional long-chain chiral structures, and 3 is a two dimensional checkerboard-type structure. Both 1 and 2 displayed a higher anticancer activity than 3 against various cancer cells, even higher than the similar mononuclear complexes and clinical anticancer drug 5-fluorouracil. The noncancerous cell lines (CCC-HEL-1) have showed that complexes 1-3 have hardly any cytotoxicity. Transmission electron microscopy was studied to show the nano-structure and π function of two complexes. The ligand 1,10-phenanthroline inserted into its enantiomer lead complex 1 stable, and the π-π interaction outside the chain made complex 2 active, which is easy to crack and pile up together. In addition, the energy gaps, UV-vis, luminescent and cyclic voltammetry were experimented to show the stable one dimensional long-chain chiral structure and the π function of two complexes.

  15. Exchange effects in a quasi-one-dimensional electron gas

    Science.gov (United States)

    Gold, A.; Ghazali, A.

    1990-04-01

    We calculate the electron exchange of a quasi-one-dimensional electron gas in a quantum-well wire of radius R0. A two-subband model is considered and the exchange self-energy for the first and second subband is calculated under the assumption that only the lowest subband is partially filled with electrons. Band-bending effects are also discussed. Results for the total energy per electron including kinetic and exchange energy are presented.

  16. Emergence of One-Dimensional Wires of Free Carriers in Transition-Metal-Dichalcogenide Nanostructures.

    Science.gov (United States)

    Gibertini, Marco; Marzari, Nicola

    2015-09-01

    We highlight the emergence of metallic states in two-dimensional transition-metal-dichalcogenide nanostructures-nanoribbons, islands, and inversion domain boundaries-as a widespread and universal phenomenon driven by the polar discontinuities occurring at their edges or boundaries. We show that such metallic states form one-dimensional wires of electrons or holes, with a free charge density that increases with the system size, up to complete screening of the polarization charge, and can also be controlled by the specific edge or boundary configurations, e.g., through chemisorption of hydrogen or sulfur atoms at the edges. For triangular islands, local polar discontinuities occur even in the absence of a total dipole moment for the island and lead to an accumulation of free carriers close to the edges, providing a consistent explanation of previous experimental observations. To further stress the universal character of these mechanisms, we show that polar discontinuities give rise to metallic states also at inversion domain boundaries. These findings underscore the potential of engineering transition-metal-dichalcogenide nanostructures for manifold applications in nano- and optoelectronics, spintronics, catalysis, and solar-energy harvesting.

  17. Obstacle Effects on One-Dimensional Translocation of ATPase

    Institute of Scientific and Technical Information of China (English)

    WANG Xian-Ju; AI Bao-Quan; LIU Liang-Gang

    2002-01-01

    We apply a general random walk model to the study of the ATPase's one-dimensional translocation along obstacle biological environment, and show the effects of random obstacles on the ATPase translocation along single stranded DNA. We find that the obstacle environment can reduce the lifetime of ATPase lattice-bound state which results in the inhibition of ATPase activity. We also carry out the ranges of rate constant of ATPase unidirectonal translocation and bidirectional translocation. Our results are consistent with the experiments and relevant theoretical consideration, and can be used to explain some physiological phenomena.

  18. Recent progress in design, synthesis, and applications of one-dimensional TiO2 nanostructured surface heterostructures: a review.

    Science.gov (United States)

    Tian, Jian; Zhao, Zhenhuan; Kumar, Anil; Boughton, Robert I; Liu, Hong

    2014-01-01

    One-dimensional TiO2 nanostructured surface heterostructures (1D TiO2NSHs) have been comprehensively studied during the past two decades because of the possible practical applications in various fields, including photocatalysis, dye-sensitized solar cells, sensors, lithium batteries, biomedicine, catalysis, and supercapacitors. Combining extensive advancements in materials science and nanotechnology, a 1D TiO2NSH material with well-controlled size, morphology, and composition has been designed and synthesized. More importantly, its superior properties, including a high aspect ratio structure, chemical stability, large specific surface area, excellent electronic or ionic charge transfer, and a specific interface effect, have attracted a great deal of interest in improving current performance and exploring new applications. In this tutorial review, we introduce the characteristics of 1D TiO2 nanostructures, the design principles for the fabrication of 1D TiO2NSHs, and we also summarize the recent progress in developing synthesis methods and applications of 1D TiO2NSHs in different fields. The relationship between the secondary phase and the 1D TiO2 nanostructure and between the performance in applications and the excellent physical properties of 1D TiO2NSHs are also discussed.

  19. Diphenylthiocarbazone (dithizone)-assisted solvothermal synthesis and optical properties of one-dimensional CdS nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Jing [State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhao Gaoling, E-mail: glzhao@zju.edu.cn [State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Yang Jinjian; Han Gaorong [State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2011-06-09

    Graphical abstract: Display Omitted Highlights: > 1-Dimensional CdS is prepared by diphenylthiocarbazone-assisted solvothermal method. > Diphenylthiocarbazone promotes the preferential growth of CdS along [0 0 2] direction. > CdS nanowires are synthesized with an appropriate diphenylthiocarbazone amount. > CdS nanowires exhibit unique optical absorption properties due to nanometer effect. - Abstract: One-dimensional (1D) cadmium sulfide (CdS) nanostructures with various aspect ratios were successfully synthesized by a diphenylthiocarbazone (dithizone)-assisted solvothermal method. The results showed that the dithizone-assisted synthesized samples had larger aspect ratio than that prepared in the absence of dithizone, and CdS nanowires with the highest aspect ratio were obtained with an appropriate dithizone amount (0.03 g/50 ml ethylenediamine in the present system). All the 1D CdS nanostructures were in hexagonal wurtzite phase. The as-synthesized large-scale CdS nanowires were in diameters ranging from 70 to 80 nm, length up to 20 {mu}m, and aspect ratios of 250-285. Further characterization indicated that the CdS nanowires were single crystalline with a preferential growth orientation of [0 0 2], c-axis. Two optical absorption peaks were observed at about 488 nm and 502 nm for the CdS nanowire sample with high aspect ratio in the optical absorption spectroscopy, which could be attributed to the nanometer effect of nanowires. It was found that the additive dithizone was a crucial factor in controlling the morphology and optical properties of the 1D CdS nanostructures. The growth mechanism of 1D CdS nanostructure and the effects of dithizone in the present system were discussed.

  20. Facile synthesis of one dimensional ZnO nanostructures for DSSC applications

    Energy Technology Data Exchange (ETDEWEB)

    Marimuthu, T.; Anandhan, N., E-mail: anandhan-kn@rediffmail.com [Advanced Materials and Thin Film Physics Lab, School of Physics, Alagappa University, Karaikudi – 630 003, India. (India)

    2016-05-06

    Development of zinc oxide (ZnO) nanostructure based third generation dye sensitized solar cell is interesting compared to conventional silicon solar cells. ZnO nanostructured thin films were electrochemically deposited onto fluorine doped tin oxide (FTO) glass substrate. The effect of ethylene-diamine-tetra-acetic acid (EDTA) on structural, morphological and optical properties is investigated using X-ray diffraction (XRD) meter, field emission scanning electron microscope (FE-SEM) and micro Raman spectroscopy. XRD patterns reveal that the prepared nanostructures are hexagonal wutrzite structures with (101) plane orientation, the nanostructure prepared using EDTA exhibits better crystallinity. FE-SEM images illustrate that the morphological changes are observed from nanorod structure to cauliflower like structure as EDTA is added. Micro Raman spectra predict that cauliflower like structure possesses a higher crystalline nature with less atomic defects compared to nanorod structures. Dye sensitized solar cell (DSSC) is constructed for the optimized cauliflower structure, and open circuit voltage, short circuit density, fill factor and efficiency are estimated from the J-V curve.

  1. Facile synthesis of one dimensional ZnO nanostructures for DSSC applications

    Science.gov (United States)

    Marimuthu, T.; Anandhan, N.

    2016-05-01

    Development of zinc oxide (ZnO) nanostructure based third generation dye sensitized solar cell is interesting compared to conventional silicon solar cells. ZnO nanostructured thin films were electrochemically deposited onto fluorine doped tin oxide (FTO) glass substrate. The effect of ethylene-diamine-tetra-acetic acid (EDTA) on structural, morphological and optical properties is investigated using X-ray diffraction (XRD) meter, field emission scanning electron microscope (FE-SEM) and micro Raman spectroscopy. XRD patterns reveal that the prepared nanostructures are hexagonal wutrzite structures with (101) plane orientation, the nanostructure prepared using EDTA exhibits better crystallinity. FE-SEM images illustrate that the morphological changes are observed from nanorod structure to cauliflower like structure as EDTA is added. Micro Raman spectra predict that cauliflower like structure possesses a higher crystalline nature with less atomic defects compared to nanorod structures. Dye sensitized solar cell (DSSC) is constructed for the optimized cauliflower structure, and open circuit voltage, short circuit density, fill factor and efficiency are estimated from the J-V curve.

  2. One-Dimensional TiO2 Nanostructured Photoanodes: From Dye-Sensitised Solar Cells to Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Jung-Ho Yun

    2016-12-01

    Full Text Available This review presents one dimensional (1D TiO2 nanostructured photoanodes for next generation solar cells such as dye-sensitised solar cells (DSCs and perovskite solar cells (PSCs. Due to the unique morphological properties, 1D TiO2 nanostructures can act as express electron channels as well as light scattering layer, leading to improved charge transport properties, such as charge separation, electron injection, and electron lifetime, and light harvesting efficiency. As 1D TiO2 nanostructures are applied to solar cells, 1D TiO2 nanostructures should be further modified to overcome some drawbacks. In this review, we have described some solutions by introducing various 1D TiO2 synthetic methods and device fabrication processes for solar cell applications, where we have described some important surface engineering and hierarchical device design strategies that facilitate charge transport and light utilisation in 1D TiO2 nanostructured photoanode system.

  3. Tuning One-Dimensional Nanostructures of Bola-Like Peptide Amphiphiles by Varying the Hydrophilic Amino Acids.

    Science.gov (United States)

    Zhao, Yurong; Deng, Li; Yang, Wei; Wang, Dong; Pambou, Elias; Lu, Zhiming; Li, Zongyi; Wang, Jiqian; King, Stephen; Rogers, Sarah; Xu, Hai; Lu, Jian R

    2016-08-01

    By combining experimental measurements and computer simulations, we here show that for the bola-like peptide amphiphiles XI4 X, where X=K, R, and H, the hydrophilic amino acid substitutions have little effect on the β-sheet hydrogen-bonding between peptide backbones. Whereas all of the peptides self-assemble into one dimensional (1D) nanostructures with completely different morphologies, that is, nanotubes and helical nanoribbons for KI4 K, flat and multilayered nanoribbons for HI4 H, and twisted and bilayered nanoribbons for RI4 R. These different 1D morphologies can be explained by the distinct stacking degrees and modes of the three peptide β-sheets along the x-direction (width) and the z-direction (height), which microscopically originate from the hydrogen-bonding ability of the sheets to solvent molecules and the pairing of hydrophilic amino acid side chains between β-sheet monolayers through stacking interactions and hydrogen bonding. These different 1D nanostructures have distinct surface chemistry and functions, with great potential in various applications exploiting the respective properties of these hydrophilic amino acids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Correlation effects for a quasi-one-dimensional polaron gas

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Paulo Cesar Miranda [Escola de Engenharia Eletrica e de Computacao, Universidade Federal de Goias, Goiania (Brazil); Borges, Antonio Newton; Osorio, Francisco Aparecido Pinto [Instituto de Fisica, Universidade Federal de Goias, Goiania (Brazil); Nucleo de Pesquisa em Fisica, Pontificia Universidade Catolica de Goias, Goiania (Brazil)

    2011-04-15

    In this work, we investigate the plasmon-LO phonon interaction effects on the intrasubband structure factor, electron-electron effective potential, and plasmon energy associated with the lowest subband in a GaAs-AlGaAs rectangular quantum-well wire (QWW) as a function of the electronic density. Our calculations are performed using the self-consistent field approximation, which includes the local-field correction (LFC) within the Singwi, Tosi, Land, and Sjolander (STLS) theory, at zero temperature and assuming a three-subband model, where only the first subband is occupied by electrons. We report for the first time dips in the structure factor spectra as a function of the quasi-one-dimensional (Q1D) plasmon-LO phonon wavevector that are directly related with the resonant split of the collective excitation energy into two branches due to the polaronic effects. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Synthesis of one-dimensional boron-related nanostructures by chemical vapor deposition

    Science.gov (United States)

    Guo, Li

    in the submicron range were used to synthesize aligned BNNTs. Fine BN nanostructures with a diameter around 10-20 nm and length up to 10 microns were grown and dispersed in the Ni dots. Nanosized Ni dots were suggested for the growth of the vertically aligned BNNTs. Boron nanowires (BNWs) were also grown by the decomposition of diborane using a thermal CVD process at a temperature of 900°C, a pressure of 20 torr, diborane flow rate (5 vol.% in hydrogen) of 5 sccm, and nitrogen flow rate of 55 sccm. These BNWs had diameters in a range of 20-200 nanometers and lengths up to several tens of micrometers. Repeatable Raman spectra indicated icosahedra B12 to be the basic building units forming the B nanowires. Amorphous BNWs with rough surface were obtained without any catalysts on different substrates, such as Si wafer or ZrB2 powders. A vapor-solid (VS) growth was proposed for the amorphous BNWs, in which the solid phase precipitated directly from the vapor phase reactions. The amorphous BNWs were modified for size and composition using a plasma CVD process containing argon, ammonia and hydrogen. The diameters of these BNWs were reduced from 200 nm to several tens of nanometers, and a small amount of N was incorporated into BNWs after the plasma treatment. On the other hand, the metal catalyst proved to be effective for the growth of crystalline BNWs. Tetragonal BNWs with smooth surface were grown on thin Ni film (1 nm) coated Si substrates. Ni attachment was observed at the tip of the BNW for the first time, which indicated that the vapor-liquid-solid (VLS) growth mechanism can be used for synthesis of the BNW. The diameters of these BNWs were strongly dependent on the size of the metal particles encapsulated in the BNWs. In summary, two boron-related nanostructures were synthesized by chemical vapor deposition (CVD) in this work. A new method was successfully developed to decrease the substrate temperature more than 400°C to fabricate boron nitride nanotubes in a

  6. Template-assisted electrodeposition of one-dimensional nanostructures for sensing and solar energy applications

    Science.gov (United States)

    Hernandez-Pagan, Emil A.

    One-dimensional nanowires and nanotubes offer unique properties that cannot be achieved with bulk materials. High surface area, strain relaxation, quantum confinement, and orthogonal light absorption and charge separation are examples. In this work, conducting polymer nanowires were synthesized by template-assisted electrodeposition. The dimensions of the nanowires could be easily controlled, and arrays or individual nanowires could be obtained. The conducting polymers synthesized were polypyrrole and poly(3,4-ethylendioxythiophene), as well as palladium-polymer and platinum-polymer composites. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) / energy-dispersive X-ray spectroscopy (EDS) were employed for structural characterization. Integration of the nanowires onto test structures was carried through electrofluidic assembly. Once assembled, the electrical properties of individual nanowires were investigated and studied for sensing of various gases. Template-assisted electrodeposition was also employed to synthesize cadmium selenide (CdSe) and copper indium diselenide (CuInSe2) nanowires. The crystal structure and crystallite domain size of the CdSe nanowires was controlled by either direct electrodeposition from an electrolyte that contained both elements or by topochemical cation exchange starting from crystalline t-Se nanowires. This was confirmed by TEM, X-ray Diffraction (XRD), and electron diffraction. CdSe nanowire photoanodes were used to study the effects of crystallite domain size on the photoelectrochemical properties. CuInSe2 nanowires were characterized by SEM, TEM/EDS, XRD, inductively coupled plasma mass spectrometry, Mott-Schottky analysis, and single wire electrical measurements. It was demonstrated that single phase p- and n-type CuInSe2 nanowires could be fabricated by this method. Since micro and nanowire arrays coupled to inexpensive catalysts are promising materials for unassisted-overall water splitting, the

  7. Splendid one-dimensional nanostructures of zinc oxide: a new nanomaterial family for nanotechnology.

    Science.gov (United States)

    Wang, Zhong Lin

    2008-10-28

    Zinc oxide is a unique material that exhibits exceptional semiconducting, piezoelectric, and pyroelectric properties. Nanostructures of ZnO are equally as important as carbon nanotubes and silicon nanowires for nanotechnology and have great potential applications in nanoelectronics, optoelectronics, sensors, field emission, light-emitting diodes, photocatalysis, nanogenerators, and nanopiezotronics. Fundamental understanding about the growth of ZnO nanowires is of critical importance for controlling their size, composition, structure, and corresponding physical and chemical properties. The papers by She et al. and Ito et al. in this issue describe the controlled growth and field-emission properties of individual nanostructures, respectively. These studies provide new approaches and insight into the controlled growth and electrical properties of ZnO nanostructures.

  8. Building one-dimensional oxide nanostructure arrays on conductive metal substrates for lithium-ion battery anodes.

    Science.gov (United States)

    Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang

    2011-01-01

    Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized alumina membrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.

  9. Atom-light interactions in quasi-one-dimensional nanostructures: A Green's-function perspective

    Science.gov (United States)

    Asenjo-Garcia, A.; Hood, J. D.; Chang, D. E.; Kimble, H. J.

    2017-03-01

    Based on a formalism that describes atom-light interactions in terms of the classical electromagnetic Green's function, we study the optical response of atoms and other quantum emitters coupled to one-dimensional photonic structures, such as cavities, waveguides, and photonic crystals. We demonstrate a clear mapping between the transmission spectra and the local Green's function, identifying signatures of dispersive and dissipative interactions between atoms. We also demonstrate the applicability of our analysis to problems involving three-level atoms, such as electromagnetically induced transparency. Finally we examine recent experiments, and anticipate future observations of atom-atom interactions in photonic band gaps.

  10. Wedding Cake Growth Mechanism in One-Dimensional and Two-Dimensional Nanostructure Evolution.

    Science.gov (United States)

    Yin, Xin; Shi, Jian; Niu, Xiaobin; Huang, Hanchen; Wang, Xudong

    2015-11-11

    The kinetic processes and atomistic mechanisms in nanostructure growth are of fundamental interest to nanomaterial syntheses with precisely controlled morphology and functionality. By programming deposition conditions at time domain, we observed the wedding cake growth mechanism in the formation of 1D and 2D ZnO nanostructures. Within a narrow growth window, the surfaces of the 1D and 2D structures were covered with a unique concentric terrace feature. This mechanism was further validated by comparing the characteristic growth rates to the screw dislocation-driven model. An interesting 1D to 2D morphology transition was also found during the wedding cake growth, when the adatoms overcome the Ehrlich-Schwoebel (ES) barrier along the edge of the top crystal facet triggered by lowering the supersaturation. The wedding cake model might be a general growth mechanism for flat-tipped nanowires that do not possess any dislocations. This study enriches our understanding on the fundamental kinetics of nanostructured crystal growth and provides a transformative strategy to achieve rational design and control of nanoscale geometry.

  11. Numerical Simulation of Synthesis of One-Dimensional Molybdenum Oxide Nanostructures in Flame Environment

    Science.gov (United States)

    Srivastava, Shubham

    The past few decades have seen a great amount of interest in the field of nanotechnology. As our world moves towards miniaturized devices nanotechnology is set to revolutionize the electronics, storage and sensing industry. Various methods for synthesis of different types of nanoparticles are being explored. A few of these processes that hold great promise for the future are the flame synthesis methods. These methods are highly efficient but at the same time it is difficult to control the morphology of the produced nanoparticles due to a high number of control parameters involved because of the complex flow processes. These issues demand a better understanding before these processes can be exploited to their maximum potential. Most numerical methods developed cater to the simulation of spherical nanoparticles. However, it is now being increasingly understood that the shape and structure of a nanoparticle plays critical role in determining its chemical, physical and electronic properties. Therefore a high level of control on the shape of nanoparticles is highly imperative. With this purpose in mind this work proposes a novel numerical scheme to simulate the synthesis of one-dimensional nanorods and further presents mathematical simulations based on it followed by validation with experimental results. The ability to predict the morphology of a nanoparticle formed by a synthesis process adds a distinct advantage. Therefore, intricate solutions have been found for the fluid flow and these have been coupled to each stage of nanoparticle development, namely monomer formation, nucleation, particle growth and particle transport. The numerical scheme takes into account all the details of the complex surface phenomena taking place on a nanorod. Later, factors are studied which transition the growth characteristics of a nanoparticle from one dimensional to a spherical structure, thus encompassing all the factors that influence the particle shape. Group characteristics of

  12. One-Dimensional TiO2 Nanostructures as Photoanodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Jie Qu

    2013-01-01

    Full Text Available Titanium dioxide (TiO2 is star materials due to its remarkable optical and electronic properties, resulting in various applications, especially in the fields of dye-sensitized solar cells (DSSCs. Photoanode is the most important part of the DSSCs, which help to adsorb dye molecules and transport the injected electrons. The size, structure, and morphology of TiO2 photoanode have been found to show significant influence on the photovoltaic performance of DSSCs. In this paper, we briefly summarize the synthesis and properties of one-dimensional (1D TiO2 nanomaterials (bare 1D TiO2 nanomaterial and 1D hierarchical TiO2 and their photovoltaic performance in DSSCs.

  13. The effect of temperature on one-dimensional nanometallic photonic crystals with coupled defects

    Indian Academy of Sciences (India)

    ABDOLRASOUL GHARAATI; ZEINAB ZARE

    2017-05-01

    Using the transfer matrix method, the effect of temperature on one-dimensional (1D) nanostructure photonic crystal with coupled defects has been investigated. One of the layers of this structure is silver. The complex refractive index of silver is dependent on temperature and wavelength. This structure is tunable with temperature and incident angle. It is found that the number of defect modes is equal to the number of coupled defects in all incident angles for both polarizations. Also by increasing the temperature, due to dissipation, the wavelength of the defect modes increases and the height of the defect modes decreases. The wavelengths of defect modes depend linearly on temperature for both polarizations in all incident angles.

  14. One-Dimensional Peptide Nanostructure Templated Growth of Iron Phosphate Nanostructures for Lithium-Ion Battery Cathodes.

    Science.gov (United States)

    Susapto, Hepi Hari; Kudu, O Ulas; Garifullin, Ruslan; Yılmaz, Eda; Guler, Mustafa O

    2016-07-13

    Template-directed synthesis of nanomaterials can provide benefits such as small crystalline size, high surface area, large surface-to-volume ratio, and structural stability. These properties are important for shorter distance in ion/electron movement and better electrode surface/electrolyte contact for energy storage applications. Here nanostructured FePO4 cathode materials were synthesized by using peptide nanostructures as a template inspired by biomineralization process. The amorphous, high surface area FePO4 nanostructures were utilized as a cathode for lithium-ion batteries. Discharge capacity of 155 mAh/g was achieved at C/20 current rate. The superior properties of biotemplated and nanostructured amorphous FePO4 are shown compared to template-free crystalline FePO4.

  15. Structural and functional engineering of one-dimensional nanostructures for device applications

    Science.gov (United States)

    Singh, Krishna Veer

    Fabrication of 1-D nanostructures has been an area of keen interest due to their application in nanodevices. Carbon nanotubes (CNTs) and semiconducting nanorods are 1-D nanostructures of great importance. There are various challenges related to structural and functional aspects of these materials, which need to be addressed for their adaptation in devices. To this end, two approaches have been developed: (1) structural engineering of the nanorods and (2) functionalization of CNTs for device applications. In first approach, a new technique to produce single crystal semiconducting nanorods was developed. Single crystalline structure of nanorods is essential to obtain reproducible performance. The novel synthesis technique 'template assisted sonoelectrochemical deposition' was utilized to develop 'copper sulfide' and 'copper indium sulfide' nanorods. The use of sonoelectrochemical method resulted in the best deposition rate as compared to stirring-assisted and regular electrochemical deposition, respectively. Observed increase in the bulk electrolyte temperature, high acoustic pressure and shock waves generated from the collapse of bubbles could explain improved mass transport and reaction rate, which results in the formation of single crystal nanorods. Nanorods in the range of 50-200nm in diameter were synthesized and electrically characterized as p-type semiconductors. Excellent structural and repeatable electrical properties of the various nanorods developed by this technique make it suitable for developing nanorods for device applications. In addition, detailed statistical analysis of the polycarbonate templates (50-200 nm nominal pore size) used in electrodeposition provided a better understanding of template's as well as nanorods' structure. In the second approach, we functionally engineered single walled carbon nanotubes (SWNTs) with peptide nucleic acid (PNA) to form functional conjugates for molecular electronics. SWNT-PNA-SWNT conjugates were synthesized

  16. Effective poroelastic model for one-dimensional wave propagation

    NARCIS (Netherlands)

    Kudarova, A.; Van Dalen, K.N.; Drijkoningen, G.G.

    2013-01-01

    An effective poroelastic model is proposed that describes seismic attenuation and dispersion in periodically layeredmedia. In this model, the layers represent mesoscopic-scale heterogeneities (larger than the grain and pore sizes but smaller than the wavelength) that can occur both in fluid and soli

  17. Aharonov-Casher Effect in One-Dimensional Wigner Crystals

    Science.gov (United States)

    Tserkovnyak, Yaroslav; Kindermann, Markus

    2010-03-01

    We theoretically study the effects of spin-orbit coupling on spin exchange in a low-density Wigner crystal. In addition to the familiar antiferromagnetic Heisenberg exchange, we find general anisotropic interactions in spin space if the exchange paths allowed by the crystal structure form loops in real space. In particular, it is shown that the two-electron exchange interaction can acquire ferromagnetic character. Tserkovnyak and Kindermann, Phys. Rev. Lett. 102 (2009) 126801.

  18. The seasonal effect in one-dimensional Daisyworld.

    Science.gov (United States)

    Biton, Eli; Gildor, Hezi

    2012-12-07

    We have studied the effects of seasonal Solar Radiation Forcing (SRF) on the climate self-regulatory capability of life, using a latitudinal-dependent Daisyworld model. Because the seasonal polarity of SRF increases poleward, habitable conditions exist in the equatorial regions year round, whereas, in the high latitudes, harsh winters cause annual extinction of life, and only the summers are inhabited or regulated by life. Seasonality affects climate regulation by two major mechanisms: (1) the cold winter conditions in the high latitudes reduce the global temperature below the optimal temperature; (2) during summer, life experiences higher SRF anomalies and, therefore, shifts to higher albedo when compared to annual mean SRF. In turn, a full capacity for temperature regulation is reached at lower SRF, and the range of SRF over which life regulates climate is significantly reduced. Lastly, initiation/extinction of life at low/highly-perturbed SRF occurs at the poles. Therefore, an irreversible global extinction occurs once life passes its regulatory capacity in the poles. We conduct extensive sensitivity analyses on various model parameters (latitudinal heat diffusion, heat capacity, and population death rate), strengthening the generality/robustness of the above net seasonal effects. Applications to other SRF fluctuation, as Milankovitch cycles are discussed.

  19. An effective one-dimensional anisotropic fingerprint enhancement algorithm

    Science.gov (United States)

    Ye, Zhendong; Xie, Mei

    2012-01-01

    Fingerprint identification is one of the most important biometric technologies. The performance of the minutiae extraction and the speed of the fingerprint verification system rely heavily on the quality of the input fingerprint images, so the enhancement of the low fingerprint is a critical and difficult step in a fingerprint verification system. In this paper we proposed an effective algorithm for fingerprint enhancement. Firstly we use normalization algorithm to reduce the variations in gray level values along ridges and valleys. Then we utilize the structure tensor approach to estimate each pixel of the fingerprint orientations. At last we propose a novel algorithm which combines the advantages of onedimensional Gabor filtering method and anisotropic method to enhance the fingerprint in recoverable region. The proposed algorithm has been evaluated on the database of Fingerprint Verification Competition 2004, and the results show that our algorithm performs within less time.

  20. Facile hydrothermal synthesis of one-dimensional nanostructured α-MnO2 for supercapacitors

    Science.gov (United States)

    Wei, Hongmei; Wang, Jinxing; Yang, Shengwei; Zhang, Yangyang; Li, Tengfei; Zhao, Shuoqing

    2016-09-01

    α-MnO2 recently becomes a promising candidate of electrode materials for high effective supercapacitors in which it possesses of unique structure of 2×2 tunnels that can provide more electrons and ions diffusion paths. In this work, different morphologies MnO2 with α-phase crystalline structure have been prepared via a one-step facile hydrothermal method by adding various reagents. Compositions, microstructures and morphologies of these as-synthesized materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and electrochemical properties of α-MnO2 electrodes were studied by the cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) in 1 M Na2SO4 aqueous solution. The specific capacitance of nanowires were 158 F g-1 while the specific capacitance of nanorods were 106 F g-1 at current density of 4 A g-1, and improved performance of the wire-like electrode material was probably ascribed to the larger specific surface area that can provide relatively more active sites for high capacity. Meanwhile, both the nanowires and nanorods of MnO2 presented fine cycle stability after continuous multiple charge/discharge times.

  1. Effect of interchain frustration in quasi-one-dimensional conductors at half-filling

    Science.gov (United States)

    Tsuchiizu, M.; Suzumura, Y.; Bourbonnais, C.

    2007-04-01

    We examine the effect of frustrated interchain hoppings t_{\\perp 1} and t_{\\perp 2} on one-dimensional Mott insulators. By applying an N_\\perp -chain two-loop renormalization-group method to the half-filled quasi-one-dimensional Hubbard model, we show that the system remains insulating even for the large t_{\\perp 1} as far as t_{\\perp 2}=0 and vice versa, whereas a metallic state emerges by increasing both interchain hoppings. We also discuss the metallic behaviour suggested in the quasi-one-dimensional organic compound (TTM-TTP)I3 under high pressure.

  2. Localized surface plasmon resonance frequency tuning in highly doped InAsSb/GaSb one-dimensional nanostructures

    Science.gov (United States)

    Milla, M. J.; Barho, F.; González-Posada, F.; Cerutti, L.; Bomers, M.; Rodriguez, J.-B.; Tournié, E.; Taliercio, T.

    2016-10-01

    We report a detailed analysis of the influence of the doping level and nanoribbon width on the localized surface plasmon resonance (LSPR) by means of reflectance measurements. The plasmonic system, based on one-dimensional periodic gratings of highly Si-doped InAsSb/GaSb semiconductor nanostructures, is fabricated by a simple, accurate and large-area technique fabrication. Increasing the doping level blueshifts the resonance peak while increasing the ribbon width results in a redshift, as confirmed by numerical simulations. This provides an efficient means of fine-tuning the LSPR properties to a target purpose of between 8-20 μm (1250-500 cm-1). Finally, we show surface plasmon resonance sensing to absorbing polymer layers. We address values of the quality factor, sensitivity and figure of merit of 16 700 nm RIU-1 and 2.5, respectively. These results demonstrate Si-doped InAsSb/GaSb to be a low-loss/high sensitive material making it very promising for the development of biosensing devices in the mid-infrared.

  3. Effective one-dimensionality of universal ac hopping conduction in the extreme disorder limit

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Schrøder, Thomas

    1996-01-01

    A phenomenological picture of ac hopping in the symmetric hopping model (regular lattice, equal site energies, random energy barriers) is proposed according to which conduction in the extreme disorder limit is dominated by essentially one-dimensional "percolation paths." Modeling a percolation path...... as strictly one dimensional with a sharp jump rate cutoff leads to an expression for the universal ac conductivity that fits computer simulations in two and three dimensions better than the effective medium approximation....

  4. Kinetically Controlled Synthesis of Pt-Based One-Dimensional Hierarchically Porous Nanostructures with Large Mesopores as Highly Efficient ORR Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shaofang; Zhu, Chengzhou; Song, Junhua; Engelhard, Mark H.; Xia, Haibing; Du, Dan; Lin, Yuehe

    2016-12-28

    Rational design and construction of Pt-based porous nanostructures with large mesopores have triggered significant considerations because of their high surface area and more efficient mass transport. Hydrochloric acid-induced kinetic reduction of metal precursors in the presence of soft template F-127 and hard template tellurium nanowires has been successfully demonstrated to construct one-dimensional hierarchical porous PtCu alloy nanostructures with large mesopores. Moreover, the electrochemical experiments demonstrated that the resultant PtCu hierarchically porous nanostructures with optimized composition exhibit enhanced electrocatalytic performance for oxygen reduction reaction.

  5. Ultracold bosons in a one-dimensional optical lattice chain: Newton's cradle and Bose enhancement effect

    Science.gov (United States)

    Wang, Ji-Guo; Yang, Shi-Jie

    2017-05-01

    We study a model to realize the long-distance correlated tunneling of ultracold bosons in a one-dimensional optical lattice chain. The model reveals the behavior of a quantum Newton's cradle, which is the perfect transfer between two macroscopic quantum states. Due to the Bose enhancement effect, we find that the resonantly tunneling through a Mott domain is greatly enhanced.

  6. Fabrication and Photocatalytic Property of One-Dimensional SrTiO3/TiO2-xNx Nanostructures

    OpenAIRE

    Huarong Zhang; Miao Guashuai; Ma Xingping; Wang Bei

    2013-01-01

    One-dimensional SrTiO3/TiO2−xNx nanostructures were prepared by the hydrothermal method and investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) measurements. The photocatalytic activities of the prepared samples were evaluated by photodegrading the methylene blue (MB) solution. According to the characterizations, the intermediate product of SrTiO3/titanate...

  7. Synthesis of one-dimensional N-doped Ga2O3 nanostructures: different morphologies and different mechanisms

    Indian Academy of Sciences (India)

    S C Vanithakumari; K K Nanda

    2011-12-01

    N-doped monoclinic Ga2O3 nanostructures of different morphologies have been synthesized by heating Ga metal in ambient air at 1150°C to 1350°C for 1 to 5 h duration. Neither catalyst nor any gas flow has been used for the synthesis of N-doped Ga2O3 nanostructures. The morphology was controlled by monitoring the curvature of the Ga droplet. Plausible growth mechanisms are discussed to explain the different morphology of the nanostructures. Elemental mapping by electron energy loss spectroscopy of the nanostructures indicate uniform distribution of Ga, O and N. It is interesting to note that we have used neither nitride source nor any gas flow but the synthesis was carried out in ambient air. We believe that ambient nitrogen acts as the source of nitrogen. Unintentional nitrogen doping of the Ga2O3 nanostructures is a straightforward method and such nanostructures could be promising candidates for white light emission.

  8. Hydrothermal fabrication of quasi-one-dimensional single-crystalline anatase TiO2 nanostructures on FTO glass and their applications in dye-sensitized solar cells.

    Science.gov (United States)

    Liao, Jin-Yun; Lei, Bing-Xin; Wang, Yu-Fen; Liu, Jun-Min; Su, Cheng-Yong; Kuang, Dai-Bin

    2011-01-24

    One-dimensional and quasi-one-dimensional semiconductor nanostructures are desirable for dye-sensitized solar cells (DSSCs), since they can provide direct pathways for the rapid collection of photogenerated electrons, which could improve the photovoltaic performance of the device. Quasi-1D single-crystalline anatase TiO(2) nanostructures have been successfully prepared on transparent, conductive fluorine-doped tin oxide (FTO) glass with a growth direction of [101] through a facile hydrothermal approach. The influences of the initial titanium n-butoxide (TBT) concentration, hydrothermal reaction temperature, and time on the length of quasi-1D anatase TiO(2) nanostructures and on the photovoltaic performance of DSSCs have been investigated in detail. A power conversion efficiency of 5.81% has been obtained based on the prepared TiO(2) nanostructure photoelectrode 6.7 μm thick and commercial N719 dye, with a short-circuit current density of 13.3 mA cm(-2) , an open-circuit voltage of 810 mV, and a fill factor of 0.54. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. One-dimensional semiconductor nanostructure based thin-film partial composite formed by transfer implantation for high-performance flexible and printable electronics at low temperature.

    Science.gov (United States)

    Moon, Kyeong-Ju; Lee, Tae-Il; Choi, Ji-Hyuk; Jeon, Joohee; Kang, Youn Hee; Kar, Jyoti Prakash; Kang, Jung Han; Yun, Ilgu; Myoung, Jae-Min

    2011-01-25

    Having high bending stability and effective gate coupling, the one-dimensional semiconductor nanostructures (ODSNs)-based thin-film partial composite was demonstrated, and its feasibility was confirmed through fabricating the Si NW thin-film partial composite on the poly(4-vinylphenol) (PVP) layer, obtaining uniform and high-performance flexible field-effect transistors (FETs). With the thin-film partial composite optimized by controlling the key steps consisting of the two-dimensional random dispersion on the hydrophilic substrate of ODSNs and the pressure-induced transfer implantation of them into the uncured thin dielectric polymer layer, the multinanowire (NW) FET devices were simply fabricated. As the NW density increases, the on-current of NW FETs increases linearly, implying that uniform NW distribution can be obtained with random directions over the entire region of the substrate despite the simplicity of the drop-casting method. The implantation of NWs by mechanical transfer printing onto the PVP layer enhanced the gate coupling and bending stability. As a result, the enhancements of the field-effect mobility and subthreshold swing and the stable device operation up to a 2.5 mm radius bending situation were achieved without an additional top passivation.

  10. Shape-Controlled Synthesis of ZnS Nanostructures: A Simple and Rapid Method for One-Dimensional Materials by Plasma

    Directory of Open Access Journals (Sweden)

    Peng Hu

    2009-01-01

    Full Text Available Abstract In this paper, ZnS one-dimensional (1D nanostructures including tetrapods, nanorods, nanobelts, and nanoslices were selectively synthesized by using RF thermal plasma in a wall-free way. The feeding rate and the cooling flow rate were the critical experimental parameters for defining the morphology of the final products. The detailed structures of synthesized ZnS nanostructures were studied through transmission electron microscope, X-ray diffraction, and high-resolution transmission electron microscope. A collision-controlled growth mechanism was proposed to explain the growth process that occurred exclusively in the gas current by a flowing way, and the whole process was completed in several seconds. In conclusion, the present synthetic route provides a facile way to synthesize ZnS and other hexagonal-structured 1D nanostructures in a rapid and scalable way.

  11. Funneling and guiding effects in ultrathin aSi-H solar cells using one-dimensional dielectric subwavelength gratings

    Science.gov (United States)

    Elshorbagy, Mahmoud H.; Alda, Javier

    2017-01-01

    Ultrathin amorphous silicon hydrogenated (aSi-H) solar cells grown on a one-dimensional (1-D) dielectric subwavelength gratings improve the short circuit current by a factor of more than 51% when compared with conventional, flat ultrathin aSi-H devices. This improvement is possible due to several mechanisms. In addition the increase in exposed area caused by the nanostructured surface, a reliable computational electromagnetic evaluation of the interaction of the solar spectrum with the cell structure demonstrates that absorption at the active layer is enhanced and also reflectivity is decreased. In addition, the absorbed power at the nonactive layers is larger, helping to increase the temperature and mitigate the Staebler-Wronski effect. The detailed analysis of the power flux inside the structure has also shown that funneling and guiding mechanism are at play, increasing the optical path within the active layer that produces a better performance of the cell.

  12. Finite-size effects in quasi-one-dimensional conductors with a charge-density wave

    Energy Technology Data Exchange (ETDEWEB)

    Zaitsev-Zotov, Sergei V [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Moscow (Russian Federation)

    2004-06-30

    Recent studies of finite-size effects in charge-density wave conductors are reviewed. Various manifestations of finite-size effects, including the transverse-size dependence of the nonlinear-conduction threshold field, the Peierls transition temperature, high-frequency conduction, and the relaxation rates of metastable states, are discussed. Resistivity jumps in thin samples, the smeared threshold field for nonlinear conduction, and threshold conduction above the Peierls transition temperature are considered, as are mesoscopic oscillations of the threshold field, one-dimensional conduction in thin crystals, absolute negative conductivity of quasi-one-dimensional conductors, the length dependence of the phase-slip voltage, and the Aharonov-Bohm oscillations in sliding CDWs. Problems yet to be solved are discussed. (reviews of topical problems)

  13. A one-dimensional stochastic approach to the study of cyclic voltammetry with adsorption effects

    OpenAIRE

    Adib J. Samin

    2016-01-01

    In this study, a one-dimensional stochastic model based on the random walk approach is used to simulate cyclic voltammetry. The model takes into account mass transport, kinetics of the redox reactions, adsorption effects and changes in the morphology of the electrode. The model is shown to display the expected behavior. Furthermore, the model shows consistent qualitative agreement with a finite difference solution. This approach allows for an understanding of phenomena on a microscopic level ...

  14. Analytic Franz-Keldysh effect in one-dimensional polar semiconductors

    CERN Document Server

    Pedersen, T G

    2003-01-01

    The optical properties of a one-dimensional polar semiconductor in a strong electric field are considered. This class of materials includes non-centrosymmetric III-V inorganic quantum wires but also polar conjugated polymers such as polymethineimine. The polar Franz-Keldysh effect is derived via an analytic expression for the complex dielectric constant including line broadening and linear field terms. Results for the high-field non-perturbative regime as well as the low-field expansion are presented.

  15. Band gap characterization and slow light effects in periodic and quasiperiodic one dimensional photonic crystal

    Science.gov (United States)

    Zaghdoudi, J.; Kuszelewicz, R.; Kanzari, M.; Rezig, B.

    2008-04-01

    Slow light offers many opportunities for photonic devices by increasing the effective interaction length of imposed refractive index changes. The slow wave effect in photonic crystals is based on their unique dispersive properties and thus entirely dielectric in nature. In this work we demonstrate an interesting opportunity to decrease drastically the group velocity of light in one-dimensional photonic crystals constructed form materials with large dielectric constant without dispersion). We use numerical analysis to study the photonic properties of periodic (Bragg mirror) and quasiperiodic one dimensional photonic crystals realized to engineer slow light effects. Various geometries of the photonic pattern have been characterized and their photonic band-gap structure analyzed. Indeed, one dimensional quasi periodic photonic multilayer structure based on Fibonacci, Thue-Morse, and Cantor sequences were studied. Quasiperiodic structures have a rich and highly fragmented reflectivity spectrum with many sharp resonant peaks that could be exploited in a microcavity system. A comparison of group velocity through periodic and quasiperiodic photonic crystals was discussed in the context of slow light propagation. The velocity control of pulses in materials is one of the promising applications of photonic crystals. The material systems used for the numerical analysis are TiO II/SiO II and Te/SiO II which have a refractive index contrast of approximately 1.59 and 3.17 respectively. The proposed structures were modelled using the Transfer Matrix Method.

  16. Consistent treatment of viscoelastic effects at junctions in one-dimensional blood flow models

    Science.gov (United States)

    Müller, Lucas O.; Leugering, Günter; Blanco, Pablo J.

    2016-06-01

    While the numerical discretization of one-dimensional blood flow models for vessels with viscoelastic wall properties is widely established, there is still no clear approach on how to couple one-dimensional segments that compose a network of viscoelastic vessels. In particular for Voigt-type viscoelastic models, assumptions with regard to boundary conditions have to be made, which normally result in neglecting the viscoelastic effect at the edge of vessels. Here we propose a coupling strategy that takes advantage of a hyperbolic reformulation of the original model and the inherent information of the resulting system. We show that applying proper coupling conditions is fundamental for preserving the physical coherence and numerical accuracy of the solution in both academic and physiologically relevant cases.

  17. Spin-Lattice Order in One-Dimensional Conductors: Beyond the RKKY Effect

    Science.gov (United States)

    Schecter, Michael; Rudner, Mark S.; Flensberg, Karsten

    2015-06-01

    We investigate magnetic order in a lattice of classical spins coupled to an isotropic gas of one-dimensional conduction electrons via local exchange interactions. The frequently discussed Ruderman-Kittel-Kasuya-Yosida effective exchange model for this system predicts that spiral order is always preferred. Here we consider the problem nonperturbatively, and find that such order vanishes above a critical value of the exchange coupling that depends strongly on the lattice spacing. The critical coupling tends to zero as the lattice spacing becomes commensurate with the Fermi wave vector, signaling the breakdown of the perturbative Ruderman-Kittel-Kasuya-Yosida picture, and spiral order, even at weak coupling. We provide the exact phase diagram for arbitrary exchange coupling and lattice spacing, and discuss its stability. Our results shed new light on the problem of utilizing a spiral spin-lattice state to drive a one-dimensional superconductor into a topological phase.

  18. Mobility and asymmetry effects in one-dimensional rock-paper-scissors games.

    Science.gov (United States)

    Venkat, Siddharth; Pleimling, Michel

    2010-02-01

    As the behavior of a system composed of cyclically competing species is strongly influenced by the presence of fluctuations, it is of interest to study cyclic dominance in low dimensions where these effects are the most prominent. We here discuss rock-paper-scissors games on a one-dimensional lattice where the interaction rates and the mobility can be species dependent. Allowing only single site occupation, we realize mobility by exchanging individuals of different species. When the interaction and swapping rates are symmetric, a strongly enhanced swapping rate yields an increased mixing of the species, leading to a mean-field-like coexistence even in one-dimensional systems. This coexistence is transient when the rates are asymmetric, and eventually only one species will survive. Interestingly, in our spatial games the dominating species can differ from the species that would dominate in the corresponding nonspatial model. We identify different regimes in the parameter space and construct the corresponding dynamical phase diagram.

  19. 纳米级的一维II-VI族化合物的合成及其电子结构研究%One-dimensional (1D) Ⅱ-Ⅳ Based Nanostructures-synthesis and Electronic Structure Study

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ Various single crystalline IIB-VIA one-dimensional nanostructures have been fabricated using thermal evaporation. Although these nanostructures possess large amount of unpassivated surface, it does not lead to dissociation of excitons, which fact indicates the high purity and high quality of the electronic structure of these nanostructures.

  20. Nanostructural evolution of one-dimensional BaTiO₃ structures by hydrothermal conversion of vertically aligned TiO₂ nanotubes.

    Science.gov (United States)

    Muñoz-Tabares, J A; Bejtka, K; Lamberti, A; Garino, N; Bianco, S; Quaglio, M; Pirri, C F; Chiodoni, A

    2016-03-28

    The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the growth of dendritic structures by aggregation and oriented attachment mechanisms. Instead, at the bottom, the low liquid/solid ratio, due to the limited amount of Ba solution that infiltrates the NTs, leads to the rapid crystallization of such a solution into BaTiO3, thus allowing the NTs to act as a template for the formation of highly oriented one-dimensional nanostructures. The in-depth analysis of the structural transformations that take place during the formation of the rod-like arrays of BaTiO3 could help elucidate the conversion mechanism, thus paving the way for the optimization of the synthesis process in view of new applications in energy harvesting devices, where easy and low temperature processing, controlled composition, morphology and functional properties are required.

  1. Impurity-limited resistance and phase interference of localized impurities under quasi-one dimensional nano-structures

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Nobuyuki, E-mail: sano@esys.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

    2015-12-28

    The impurity-limited resistance and the effect of the phase interference among localized multiple impurities in the quasi-one dimensional (quasi-1D) nanowire structures are systematically investigated under the framework of the scattering theory. We derive theoretical expressions of the impurity-limited resistance in the nanowire under the linear response regime from the Landauer formula and from the Boltzmann transport equation (BTE) with the relaxation time approximation. We show that the formula from the BTE exactly coincides with that from the Landauer approach with the weak-scattering limit when the energy spectrum of the in-coming electrons from the reservoirs is narrow and, thus, point out a possibility that the distinction of the impurity-limited resistances derived from the Landauer formula and that of the BTE could be made clear. The derived formulas are applied to the quasi-1D nanowires doped with multiple localized impurities with short-range scattering potential and the validity of various approximations on the resistance are discussed. It is shown that impurity scattering becomes so strong under the nanowire structures that the weak-scattering limit breaks down in most cases. Thus, both phase interference and phase randomization simultaneously play a crucial role in determining the impurity-limited resistance even under the fully coherent framework. When the impurity separation along the wire axis direction is small, the constructive phase interference dominates and the resistance is much greater than the average resistance. As the separation becomes larger, however, it approaches the series resistance of the single-impurity resistance due to the phase randomization. Furthermore, under the uniform configuration of impurities, the space-average resistance of multiple impurities at room temperature is very close to the series resistance of the single-impurity resistance, and thus, each impurity could be regarded as an independent scattering center. The

  2. Effect of Temperature on Polaron Stability in a One-Dimensional Organic Lattice

    Institute of Scientific and Technical Information of China (English)

    LIU Wen; LI Yuan; QU Zhen; GAO gun; YIN Sun; LIU De-Sheng

    2009-01-01

    Effect of temperature on the polaron stability in a one-dimensional organic lattice is investigated within the Su-Schrieffer-Heeger model.The temperature effect is simulated by introducing random forces to the equation of the lattice motion.It is found that the localized polaron state becomes delocalized even at low temperatures.The time of polaron keeping localized depends on the magnitude of temperatures.By taking into account the thermal effect,we find that the dissociation field is weaker as compared with earlier works.

  3. Antiresonance Effect in Electronic Tunnelling through a One-Dimensional Quantum Dot Chain

    Institute of Scientific and Technical Information of China (English)

    SUN Pu-Nan

    2006-01-01

    @@ Electronic tunnelling through a one-dimensional quantum dot chain is theoretically studied, when two leads couple to the individual component quantum dots of the chain arbitrarily. If there are some dangling quantum dots in the chain outside the leads, the electron tunnelling through the quantum dot chain is wholly forbidden while the energy of the incident electron is just equal to the molecular energy levels of the dangling quantum dots,which is known as the antiresonance effect. In addition, the influence of electron interaction on the antiresonance effect is discussed within the Hartree-Fock approximation.

  4. The effect of magnetic frustrations in a structure of Quasi-One-Dimensional Heisenberg antiferromagnetic chain

    Energy Technology Data Exchange (ETDEWEB)

    Cui, L.; Wang, F. [Suqian College, Fundamental Department, Suqian 223800 (China); Zhang, S.J. [Hubei University of Automotive Technology, Shiyan 442002 (China); Hu, Y.J., E-mail: eric8222@126.com [Hubei University of Automotive Technology, Shiyan 442002 (China)

    2014-10-15

    Using exact numerical diagonalization and density-matrix renormalization group method, we study the effect of magnetic frustrations due to next-nearest-neighbor bonds in a structure of periodically doping spins beside every spin side of the same sublattice of the 1D HAF linear chain, which is popularly known as Quasi-One-Dimensional Heisenberg Antiferromagnetic chain. As a result of the frustrations, the quantum disordered phase (gapped) also appears in the quantum case, except that the ferrimagnetic state in the non-frustrations case and the caned phase appeared in the classical case. For quantum disordered phase, tetramer–dimmer state is predominant and the spin gap is opened.

  5. Green's functions of one-dimensional quasicrystal bi-material with piezoelectric effect

    Science.gov (United States)

    Zhang, Liangliang; Wu, Di; Xu, Wenshuai; Yang, Lianzhi; Ricoeur, Andreas; Wang, Zhibin; Gao, Yang

    2016-09-01

    Based on the Stroh formalism of one-dimensional quasicrystals with piezoelectric effect, the problems of an infinite plane composed of two different quasicrystal half-planes are taken into account. The solutions of the internal and interfacial Green's functions of quasicrystal bi-material are obtained. Moreover, numerical examples are analyzed for a quasicrystal bi-material subjected to line forces or line dislocations, showing the contour maps of the coupled fields. The impacts of changing material constants on the coupled field components are investigated.

  6. 一维纳米结构氧化锌的水热法制备及紫外光敏特性研究%Hydrothermal Synthesis of One Dimensional Nanostructure ZnO and Its Ultraviolet Photosensitivity Characteristics

    Institute of Scientific and Technical Information of China (English)

    张祥涛; 吴起白; 张海燕; 魏爱香; 刘俊

    2009-01-01

    在陶瓷衬底上制作叉指状金电极,采用低温水热法生长一维纳米结构氧化锌,制得氧化锌紫外光电导型探测器.探讨了反应溶液的浓度对氧化锌纳米结构形貌及紫外光电导特性的影响.X射线衍射分析表明,产物为六方纤锌矿结构的ZnO.扫描电镜观察显示.产物为一维纳米结构,因反应溶液浓度的不同直径介于80~500nm.光电测试表明,一维纳米结构氧化锌的紫外光电导特性受其表面形貌的影响显著.%Comb-shaped Au electrodes are prepared on ceramic substrate firstly, and then the one dimensional nanostructure is synthesised by hydrothermal method in order to get ZnO UV detector. The effect of the concentration of solution on the growth of nanostructure ZnO and UV sensitivity has been studied. X-ray diffraction patterns indicate that the product is pure phase zinc oxide. The morphology of one dimensional nanostructure is characterized by SEM. The diameter of one dimensional nanostructure ZnO obtained is 80~500nm. Test shows that the UV conductivity properties of ZnO are affected by their surface topography.

  7. Synthesis and characterization of one-dimensional Ag-doped ZnO/Ga-doped ZnO coaxial nanostructure diodes.

    Science.gov (United States)

    Chiu, Hsien-Ming; Chang, Yu-Tsui; Wu, Wen-Wei; Wu, Jenn-Ming

    2014-04-09

    In the pursuit of high injection current diode nanodevices, entire one-dimensional (1D) ZnO coaxial nanostructures with p-n homojunctions is one of the ideal structures. In this study, we synthesized entire 1D ZnO-based coaxial homojunction diodes with p-type Ag-doped ZnO (SZO) nanostructure shells covering n-type Ga-doped ZnO (GZO) nanopagoda (NPG) cores by a metal-organic chemical vapor deposition (MOCVD) technique. The entire 1D SZO-GZO and SZO-ZnO coaxial nanostructures exhibit better diode characteristics, such as lower threshold voltage, better rectification ratios, and better ideality factor n, than that reported for either 2D or 2D-1D p-n heterojunction and/or homojunction diodes. The binding energies of Ga and Ag were evaluated by low-temperature and temperature-dependent photoluminescence. In comparison, the SZO-GZO coaxial p-n nanostructures display better diode performance than the SZO-ZnO ones.

  8. Effect of disorders on topological phases in one-dimensional optical superlattices

    Science.gov (United States)

    Zhizhou, Wang; Yidong, Wu; Huijing, Du; Xili, Jing

    2016-07-01

    In a recent paper, Lang et al. proposed that edge states and topological phases can be observed in one-dimensional optical superlattices. They showed that the topological phases can be revealed by observing the density profile of a trapped fermion system, which displays plateaus with their positions. However, disorders are not considered in their model. To study the effect of disorders on the topological phases, we introduce random potentials to the model for optical superlattcies. Our calculations show that edge states are robust against the disorders. We find the edge states are very sensitive to the number of the sites in the optical superlattice and we propose a simple rule to describe the relationship between the edge states and the number of sites. The density plateaus are also robust against weak disorders provided that the average density is calculated over a long interval. The widths of the plateaus are proportional to the widths of the bulk energy gaps when there are disorders. The disorders can diminish the bulk energy gaps. So the widths of the plateaus decrease with the increase of disorders and the density plateaus disappear when disorders are too strong. The results in our paper can be used to guide the experimental detection of topological phases in one-dimensional systems. Project supported by the National Natural Science Foundation of China (Grant No. 41174116), the Graduate Student Education Teaching Reform Project, China (Grant No. JG201512), and the Young Teachers’ Research Project of Yanshan University, China (Grant No. 13LGB028).

  9. Nanostructural evolution of one-dimensional BaTiO3 structures by hydrothermal conversion of vertically aligned TiO2 nanotubes

    Science.gov (United States)

    Muñoz-Tabares, J. A.; Bejtka, K.; Lamberti, A.; Garino, N.; Bianco, S.; Quaglio, M.; Pirri, C. F.; Chiodoni, A.

    2016-03-01

    The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the growth of dendritic structures by aggregation and oriented attachment mechanisms. Instead, at the bottom, the low liquid/solid ratio, due to the limited amount of Ba solution that infiltrates the NTs, leads to the rapid crystallization of such a solution into BaTiO3, thus allowing the NTs to act as a template for the formation of highly oriented one-dimensional nanostructures. The in-depth analysis of the structural transformations that take place during the formation of the rod-like arrays of BaTiO3 could help elucidate the conversion mechanism, thus paving the way for the optimization of the synthesis process in view of new applications in energy harvesting devices, where easy and low temperature processing, controlled composition, morphology and functional properties are required.The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the

  10. Diffusion related isotopic fractionation effects with one-dimensional advective–dispersive transport

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Bruce S. [Civil Engineering Department, University of Toronto, 35 St George Street, Toronto, ON M5S 1A4 (Canada); Lollar, Barbara Sherwood [Earth Sciences Department, University of Toronto, 22 Russell Street, Toronto, ON M5S 3B1 (Canada); Passeport, Elodie [Civil Engineering Department, University of Toronto, 35 St George Street, Toronto, ON M5S 1A4 (Canada); Chemical Engineering and Applied Chemistry Department, University of Toronto, 200 College Street, Toronto, ON M5S 3E5 (Canada); Sleep, Brent E., E-mail: sleep@ecf.utoronto.ca [Civil Engineering Department, University of Toronto, 35 St George Street, Toronto, ON M5S 1A4 (Canada)

    2016-04-15

    Aqueous phase diffusion-related isotope fractionation (DRIF) for carbon isotopes was investigated for common groundwater contaminants in systems in which transport could be considered to be one-dimensional. This paper focuses not only on theoretically observable DRIF effects in these systems but introduces the important concept of constraining “observable” DRIF based on constraints imposed by the scale of measurements in the field, and on standard limits of detection and analytical uncertainty. Specifically, constraints for the detection of DRIF were determined in terms of the diffusive fractionation factor, the initial concentration of contaminants (C{sub 0}), the method detection limit (MDL) for isotopic analysis, the transport time, and the ratio of the longitudinal mechanical dispersion coefficient to effective molecular diffusion coefficient (D{sub mech}/D{sub eff}). The results allow a determination of field conditions under which DRIF may be an important factor in the use of stable carbon isotope measurements for evaluation of contaminant transport and transformation for one-dimensional advective–dispersive transport. This study demonstrates that for diffusion-dominated transport of BTEX, MTBE, and chlorinated ethenes, DRIF effects are only detectable for the smaller molar mass compounds such as vinyl chloride for C{sub 0}/MDL ratios of 50 or higher. Much larger C{sub 0}/MDL ratios, corresponding to higher source concentrations or lower detection limits, are necessary for DRIF to be detectable for the higher molar mass compounds. The distance over which DRIF is observable for VC is small (less than 1 m) for a relatively young diffusive plume (< 100 years), and DRIF will not easily be detected by using the conventional sampling approach with “typical” well spacing (at least several meters). With contaminant transport by advection, mechanical dispersion, and molecular diffusion this study suggests that in field sites where D{sub mech}/D{sub eff} is

  11. Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}): Peroxovanadate sol gel synthesis and structural study

    Energy Technology Data Exchange (ETDEWEB)

    Langie da Silva, Douglas, E-mail: douglas.langie@ufpel.edu.br [Departamento de Física, Universidade Federal de Pelotas, Caixa Postal 354, Pelotas 96010-900 (Brazil); Moreira, Eduardo Ceretta [Laboratório de Espectroscopia, Universidade Federal do Pampa, Campus Bagé, Bagé 96400-970 (Brazil); Dias, Fábio Teixeira; Neves Vieira, Valdemar das [Departamento de Física, Universidade Federal de Pelotas, Caixa Postal 354, Pelotas 96010-900 (Brazil); Brandt, Iuri Stefani; Cas Viegas, Alexandre da; Pasa, André Avelino [Laboratório de Filmes Finos e Superfícies, Universidade Federal de Santa Catarina, Caixa Postal 476, Florianópolis 88.040-900 (Brazil)

    2015-01-15

    Nanostructured cobalt vanadium oxide (V{sub 2}O{sub 5}) xerogels spread onto crystalline Si substrates were synthesized via peroxovanadate sol gel route. The resulting products were characterized by distinct experimental techniques. The surface morphology and the nanostructure of xerogels correlate with Co concentration. The decrease of the structural coherence length is followed by the formation of a loose network of nanopores when the concentration of intercalated species was greater than 4 at% of Co. The efficiency of the synthesis route also drops with the increase of Co concentration. The interaction between the Co(OH{sub 2}){sub 6}{sup 2+} cations and the (H{sub 2}V{sub 10}O{sub 28}){sup 4−} anions during the synthesis was suggested as a possible explanation for the incomplete condensation of the V{sub 2}O{sub 5} gel. Finally the experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5}. In this scenario two possible preferential occupation sites for the metallic atoms in the framework of the xerogel were proposed. - Graphical abstract: Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}) nanoribbons synthesized by peroxovanadate sol gel route. - Highlights: • Nanostructured cobalt V{sub 2}O{sub 5} gel spread onto c{sub S}i were synthesized via peroxovanadate sol gel route. • The micro and nanostructure correlates with the cobalt content. • The efficiency of the synthesis route shows to be also dependent of Co content. • The experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5} xerogel.

  12. Boundary-induced dynamics in one-dimensional topological systems and memory effects of edge modes

    Science.gov (United States)

    He, Yan; Chien, Chih-Chun

    2016-07-01

    Dynamics induced by a change of boundary conditions reveals rate-dependent signatures associated with topological properties in one-dimensional Kitaev chain and SSH model. While the perturbation from a change of the boundary propagates into the bulk, the density of topological edge modes in the case of transforming to open boundary condition reaches steady states. The steady-state density depends on the transformation rate of the boundary and serves as an illustration of quantum memory effects in topological systems. Moreover, while a link is physically broken as the boundary condition changes, some correlation functions can remain finite across the broken link and keep a record of the initial condition. By testing those phenomena in the nontopological regimes of the two models, none of the interesting signatures of memory effects can be observed. Our results thus contrast the importance of topological properties in boundary-induced dynamics.

  13. Simultaneous quasi-one-dimensional propagation and tuning of upconversion luminescence through waveguide effect.

    Science.gov (United States)

    Gao, Dangli; Tian, Dongping; Zhang, Xiangyu; Gao, Wei

    2016-02-29

    Luminescence-based waveguide is widely investigated as a promising alternative to conquer the difficulties of efficiently coupling light into a waveguide. But applications have been still limited due to employing blue or ultraviolet light as excitation source with the lower penetration depth leading to a weak guided light. Here, we show a quasi-one-dimensional propagation of luminescence and then resulting in a strong luminescence output from the top end of a single NaYF4:Yb(3+)/Er(3+) microtube under near infrared light excitation. The mechanism of upconversion propagation, based on the optical waveguide effect accompanied with energy migration, is proposed. The efficiency of luminescence output is highly dependent on the concentration of dopant ions, excitation power, morphology, and crystallinity of tube as an indirect evidence of the existence of the optical actived waveguide effect. These findings provide the possibility for the construction of upconversion fiber laser.

  14. Simultaneous quasi-one-dimensional propagation and tuning of upconversion luminescence through waveguide effect

    Science.gov (United States)

    Gao, Dangli; Tian, Dongping; Zhang, Xiangyu; Gao, Wei

    2016-02-01

    Luminescence-based waveguide is widely investigated as a promising alternative to conquer the difficulties of efficiently coupling light into a waveguide. But applications have been still limited due to employing blue or ultraviolet light as excitation source with the lower penetration depth leading to a weak guided light. Here, we show a quasi-one-dimensional propagation of luminescence and then resulting in a strong luminescence output from the top end of a single NaYF4:Yb3+/Er3+ microtube under near infrared light excitation. The mechanism of upconversion propagation, based on the optical waveguide effect accompanied with energy migration, is proposed. The efficiency of luminescence output is highly dependent on the concentration of dopant ions, excitation power, morphology, and crystallinity of tube as an indirect evidence of the existence of the optical actived waveguide effect. These findings provide the possibility for the construction of upconversion fiber laser.

  15. Green's functions of one-dimensional quasicrystal bi-material with piezoelectric effect

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Liangliang [College of Engineering, China Agricultural University, Beijing 100083 (China); Sinomatech Wind Power Blade Co., Ltd, Beijing 100092 (China); Wu, Di [College of Engineering, China Agricultural University, Beijing 100083 (China); Xu, Wenshuai [College of Science, China Agricultural University, Beijing 100083 (China); Yang, Lianzhi [Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083 (China); Ricoeur, Andreas; Wang, Zhibin [Institute of Mechanics, University of Kassel, 34125 Kassel (Germany); Gao, Yang, E-mail: gaoyangg@gmail.com [College of Science, China Agricultural University, Beijing 100083 (China)

    2016-09-16

    Based on the Stroh formalism of one-dimensional quasicrystals with piezoelectric effect, the problems of an infinite plane composed of two different quasicrystal half-planes are taken into account. The solutions of the internal and interfacial Green's functions of quasicrystal bi-material are obtained. Moreover, numerical examples are analyzed for a quasicrystal bi-material subjected to line forces or line dislocations, showing the contour maps of the coupled fields. The impacts of changing material constants on the coupled field components are investigated. - Highlights: • Green's functions of 1D piezoelectric quasicrystal bi-material are studied. • The coupled fields subjected to line forces or line dislocations are obtained. • Mechanical behavior under the effect of different material constants is researched.

  16. Impurity effects on the band structure of one-dimensional photonic crystals: Experiment and theory

    CERN Document Server

    Luna-Acosta, G A; Kuhl, U; Stoeckmann, H -J

    2007-01-01

    We study the effects of single impurities on the transmission in microwave realizations of the photonic Kronig-Penney model, consisting of arrays of Teflon pieces alternating with air spacings in a microwave guide. As only the first propagating mode is considered, the system is essentially one dimensional obeying the Helmholtz equation. We derive analytical closed form expressions from which the band structure, frequency of defect modes, and band profiles can be determined. These agree very well with experimental data for all types of single defects considered (e. g. interstitial, substitutional) and shows that our experimental set-up serves to explore some of the phenomena occurring in more sophisticated experiments. Conversely, based on the understanding provided by our formulas, information about the unknown impurity can be determined by simply observing certain features in the experimental data for the transmission. Further, our results are directly applicable to the closely related quantum 1D Kronig-Penn...

  17. Impurity effects on the band structure of one-dimensional photonic crystals: experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Luna-Acosta, G A [Instituto de Fisica, BUAP Apartado Postal J-48, 72570 Puebla (Mexico); Schanze, H; Kuhl, U; Stoeckmann, H-J [Fachbereich Physik der Philipps-Universitaet Marburg, Renthof 5, D-35032 (Germany)], E-mail: gluna@sirio.ifuap.buap.mx

    2008-04-15

    We study the effects of single impurities on the transmission in microwave realizations of the photonic Kronig-Penney model, consisting of arrays of Teflon pieces alternating with air spacings in a microwave guide. As only the first propagating mode is considered, the system is essentially one-dimensional (1D) obeying the Helmholtz equation. We derive analytical closed form expressions from which the band structure, frequency of defect modes and band profiles can be determined. These agree very well with experimental data for all types of single defects considered (e.g. interstitial and substitutional) and show that our experimental set-up serves to explore some of the phenomena occurring in more sophisticated experiments. Conversely, based on the understanding provided by our formulae, information about the unknown impurity can be determined by simply observing certain features in the experimental data for the transmission. Further, our results are directly applicable to the closely related quantum 1D Kronig-Penney model.

  18. Effect of Sulfur Precursor on Dimensions of One-dimensional CdS Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    M. Maleki; Sh. Mirdamadi; R.Ghasemzadeh; M.Sasani Ghamsari

    2009-01-01

    One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor, elemental sulfur and Na2S, as a sulfur precursor, and ethylenediamine as a solvent at 150℃ for 5 h. The nanocrystals were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-Vis absorption spectroscopy. XRD patterns indicate that both Na2S and elemental sulfur as the sulfur precursor result in CdS nanorods with wurtzite phase (hexagonal structure). SEM and TEM images show that diameter of CdS nanorods can be decreased using Na2S instead of elemental sulfur. For the growth of CdS nanorods, a mechanism has been proposed. Uv-Vis absorption of CdS nanorods (sulfur precursor: Na2S) was shown blue shift to 485 nm due to the quantum size effect.

  19. Size effects in electrical and magnetic properties of quasi-one-dimensional tin wires in asbestos

    Science.gov (United States)

    Chernyaev, A. V.; Shamshur, D. V.; Fokin, A. V.; Kalmykov, A. E.; Kumzerov, Yu. A.; Sorokin, L. M.; Parfen'ev, R. V.; Lashkul, A.

    2016-03-01

    Bulk composites have been prepared based on one-dimensional fibers of natural chrisothil-asbestos with various internal diameters ( d = 6-2.5 nm) filled with tin. The electrical and magnetic properties of quasi-one-dimensional Sn wires have been studied at low temperatures. The electrical properties have been measured at T = 300 K at a pressure P = 10 kbar. It has been found that the superconducting (SC) characteristics of the nanocomposites (critical temperature T c and critical magnetic field H c) increase as the Sn filament diameter decreases. The temperature spreading of the resistive SC transition also increases as the Sn filament diameter decreases, which is explained by the SC order parameter fluctuations. The size effects (the increase in critical temperature T c and transition width Δ T c) in Sn nanofilaments are well described by the independent Aslamazov-Larkin and Langer-Ambegaokara fluctuation theories, which makes it possible to find the dependence of T c of the diffuse SC transition on the nanowire diameter. Using the temperature and magnetic-field dependences of the magnetic moment M( T, H), it has been found that the superconductor-normal metal phase diagram of the Sn-asbestos nanocomposite has a wider region of the SC state in T and H as compared to the data for bulk Sn. The magnetic properties of chrisotil-asbestos fibers unfilled with Sn have been studied. It has been found that the Curie law is fulfilled and that the superparamagnetism is absent in such samples. The obtained results indicate the absence of magnetically ordered impurities (magnetite) in the chrisotil-asbestos matrix, which allowed one to not consider the problem of the interaction of the magnetic subsystem of the asbestos matrix and the superconducting subsystem of Sn nanowires.

  20. One-dimensional carbon nanotube/SnO2/noble metal nanoparticle hybrid nanostructure: synthesis, characterization, and electrochemical sensing.

    Science.gov (United States)

    Fang, Youxing; Guo, Shaojun; Zhu, Chengzhou; Dong, Shaojun; Wang, Erkang

    2010-08-02

    Herein we report a facile and efficient method for self-assembling noble-metal nanoparticles (NPs) to the surface of SnO(2)-coated carbon nanotubes (CNT@SnO(2)) to construct CNT@SnO(2)/noble metal NP hybrids. By using SnCl(4) as the precursor of the SnO(2) shell on the surface of CNTs, the hydrolysis speed of SnCl(4) was slowed down in ethanol containing a trace amount of urea and water. The coaxial nanostructure of CNT@SnO(2) was confirmed by using X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). It was found that the coating layer of SnO(2) was homogeneous with the mean thickness of 8 nm. The CNT@SnO(2)/noble-metal NP hybrids were obtained by mixing noble-metal NPs with as-prepared CNT@SnO(2) coaxial nanocables by means of a self-assembly strategy. With the amino group terminated, the CNT@SnO(2) coaxial nanocable can readily adsorb the as-prepared noble-metal NPs (Au, Ag, Au-Pt, and Au-Pd NPs). The presence of an amino group at the surface of SnO(2) was proved by use of X-ray photoelectron spectroscopy (XPS). In addition, H(2)O(2) sensing by amperometric methods could serve as detection models for investigating the electrocatalytic ability of as-prepared hybrid materials. It was found that wide linear ranges and low detection limits were obtained by using the enzyme-free CNT@SnO(2)@Au-Pt modified electrode, which indicated the potential utilizations of the hybrid based on CNT@SnO(2) for electrochemical sensing.

  1. Fabrication of FOX-7 quasi-three-dimensional grids of one-dimensional nanostructures via a spray freeze-drying technique and size-dependence of thermal properties.

    Science.gov (United States)

    Huang, Bing; Qiao, Zhiqiang; Nie, Fude; Cao, Minhua; Su, Jing; Huang, Hui; Hu, Changwen

    2010-12-15

    1,1-Diamino-2,2-dinitroethylene (C(2)H(4)N(4)O(4), FOX-7) quasi-three-dimensional (3D) grids, a promising high-energy-density material with superior sensitivity properties, were synthesized by a spray freeze-drying technique. The FOX-7 3D grids were constructed from one-dimensional nanostructures. The sizes and structures of the FOX-7 3D grids strongly depend on the concentration of the aqueous solution of FOX-7. A possible formation mechanism of this structure was proposed in detail. Thermal analysis reveals that decrease in average particle sizes of FOX-7 grids results in a lower decomposition temperature and a much higher decomposition rate, which is in agreement with those reported about inorganic nanomaterials.

  2. Effect of Inter-particle Interactions on Pair Correlations of One-Dimensional Anyon Gases

    Science.gov (United States)

    Li, Yan; He, Zhi

    2015-10-01

    The pair correlation function of the one-dimensional interacting anyonic system in its ground state is investigated based on the exact Bethe ansatz solution for arbitrary coupling constant () and statistics parameter (). We discuss the effects of the inter-particle interactions and the fractional statistics on the pair correlations in both position and momentum spaces. The pair correlations of anyons with coupling constant c and statistical parameter in position space are identical to that of the Lieb-Liniger Bose model with effective coupling constant . Besides the effect of renormalized coupling, the correlations in momentum space reveal more effects induced by the statistics parameter. The anyonic statistics results in the nonsymmetric correlation when the statistics parameter deviates from 0 (Bose statistics) and (Fermi statistics) for any coupling constant c. The correlations display peaks and dips, representing the bunching and antibunching of atoms, respectively. The correlations show crossover from bunching behavior of bosons to antibunching behavior of fermions as varies from 0 to for arbitrary coupling constant. Besides the fractional effect, we also observe the effects induced by the inter-particle interactions in the momentum correlations. With the increase of the coupling constant, the bunching effect between particles weakens and the antibunching points in the correlations shift.

  3. Synthesis of one-dimensional gold nanostructures and the electrochemical application of the nanohybrid containing functionalized graphene oxide for cholesterol biosensing.

    Science.gov (United States)

    Nandini, Seetharamaiah; Nalini, Seetharamaiah; Reddy, M B Madhusudana; Suresh, Gurukar Shivappa; Melo, Jose Savio; Niranjana, Pathappa; Sanetuntikul, Jakkid; Shanmugam, Sangaraju

    2016-08-01

    This manuscript reports a new approach for the synthesis of one dimensional gold nanostructure (AuNs) and its application in the development of cholesterol biosensor. Au nanostructures have been synthesized by exploiting β-diphenylalanine (β-FF) as an sacrificial template, whereas the Au nanoparticles (AuNPs) were synthesized by ultrasound irradiation. X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive analysis of X-rays (EDAX) have been employed to characterize the morphology and composition of the prepared samples. With the aim to develop a highly sensitive cholesterol biosensor, cholesterol oxidase (ChOx) was immobilized on AuNs which were appended on the graphite (Gr) electrode via chemisorption onto thiol-functionalized graphene oxide (GO-SH). This Gr/GO-SH/AuNs/ChOx biosensor has been characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy and chronoamperometry. CV results indicated a direct electron transfer between the enzyme and the electrode surface. A new potentiostat intermitant titration technique (PITT) has been studied to determine the diffusion coefficient and maxima potential value. The proposed biosensor showed rapid response, high sensitivity, wide linear range and low detection limit. Furthermore, our AuNs modified electrode showed excellent selectivity, repeatability, reproducibility and long term stability. The proposed electrode has also been used successfully to determine cholesterol in serum samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. The effect of cross flow on one-dimensional spectra measured using hot wires

    Science.gov (United States)

    Ewing, D.

    Expressions were developed to estimate the cross-flow error that occurs in the one-dimensional velocity spectra determined by applying Taylor's frozen field hypothesis to measurements with single- and cross-wire probes. The cross-flow error and the error caused by the unsteady convection of the small-scale motions were evaluated for typical measurements. It was found that the cross-flow error could be significant in inertial range of the measured one-dimensional spectra, and was much larger than the error caused by the unsteady convection of the small-scale motions in the one-dimensional spectra of the cross-stream velocity components, $ F2}{22 {( {k1 } )} and F1}{33 {( {k1 } )} . The results indicate that the one-dimensional spectra of the streamwise velocity component F1}{11 {( {k1 } )} $ measured with a single-wire probe should be significantly more accurate than the spectra measured with a cross-wire probe. The cross-flow error in the one-dimensional spectra also becomes much less important in the dissipation range of the measured spectra.

  5. One-dimensional photonic crystals

    NARCIS (Netherlands)

    Shen, Huaizhong; Wang, Zhanhua; Wu, Yuxin; Yang, Bai

    2016-01-01

    A one-dimensional photonic crystal (1DPC), which is a periodic nanostructure with a refractive index distribution along one direction, has been widely studied by scientists. In this review, materials and methods for 1DPC fabrication are summarized. Applications are listed, with a special emphasis

  6. The effects of one-dimensional glide on the reaction kinetics of interstitial clusters

    DEFF Research Database (Denmark)

    Heinisch, H.L.; Singh, B.N.; Golubov, S.I.

    2000-01-01

    Collision cascades in metals produce small interstitial clusters and perfect dislocation loops that glide in thermally activated one-dimensional (1D) random walks. These gliding defects can change their Burgers vectors by thermal activation or by interactions with other defects. Their migration i...

  7. Fabrication and Photocatalytic Property of One-Dimensional SrTiO3/TiO2-xNx Nanostructures

    Directory of Open Access Journals (Sweden)

    Huarong Zhang

    2013-01-01

    Full Text Available One-dimensional SrTiO3/TiO2−xNx nanostructures were prepared by the hydrothermal method and investigated by X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS measurements. The photocatalytic activities of the prepared samples were evaluated by photodegrading the methylene blue (MB solution. According to the characterizations, the intermediate product of SrTiO3/titanate nanotubes was presented after hydrothermal processing of the TiO2−xNx nanoparticles with the mixed solution of NaOH and Sr(NO32. The final product of SrTiO3/TiO2−xNx nanorods was obtained after calcining the intermediate. As compared to the TiO2−xNx nanoparticles, the absorption performance of SrTiO3/titanate nanotubes or SrTiO3/TiO2−xNx nanorods was depressed, instead of improving it. The mechanisms of the absorption property changes were discussed. The SrTiO3/TiO2−xNx nanorods presented better photocatalytic activity than the TiO2−xNx nanoparticles or nanorods. However, due to overmuch adsorption, the SrTiO3/titanate nanotubes gave ordinary photocatalytic performances.

  8. Effect of ice-albedo feedback on global sensitivity in a one-dimensional radiative-convective climate model

    Science.gov (United States)

    Wang, W.-C.; Stone, P. H.

    1980-01-01

    The feedback between the ice albedo and temperature is included in a one-dimensional radiative-convective climate model. The effect of this feedback on global sensitivity to changes in solar constant is studied for the current climate conditions. This ice-albedo feedback amplifies global sensitivity by 26 and 39%, respectively, for assumptions of fixed cloud altitude and fixed cloud temperature. The global sensitivity is not affected significantly if the latitudinal variations of mean solar zenith angle and cloud cover are included in the global model. The differences in global sensitivity between one-dimensional radiative-convective models and energy balance models are examined. It is shown that the models are in close agreement when the same feedback mechanisms are included. The one-dimensional radiative-convective model with ice-albedo feedback included is used to compute the equilibrium ice line as a function of solar constant.

  9. Finite-size effects for the gap in the excitation spectrum of the one-dimensional Hubbard model

    NARCIS (Netherlands)

    Colomé-Tatché, M.; Matveenko, S.I.; Shlyapnikov, G.V.

    2010-01-01

    We study finite-size effects for the gap of the quasiparticle excitation spectrum in the weakly interacting regime one-dimensional Hubbard model with on-site attraction. Two types of corrections to the result of the thermodynamic limit are obtained. Aside from a power law (conformal) correction due

  10. Finite-size effects for the gap in the excitation spectrum of the one-dimensional Hubbard model

    NARCIS (Netherlands)

    Colomé-Tatché, M.; Matveenko, S.I.; Shlyapnikov, G.V.

    2010-01-01

    We study finite-size effects for the gap of the quasiparticle excitation spectrum in the weakly interacting regime one-dimensional Hubbard model with on-site attraction. Two types of corrections to the result of the thermodynamic limit are obtained. Aside from a power law (conformal) correction due

  11. Diffusion in a tube of varying cross section: Numerical study of reduction to effective one-dimensional description

    Science.gov (United States)

    Berezhkovskii, A. M.; Pustovoit, M. A.; Bezrukov, S. M.

    2007-04-01

    Brownian dynamics simulations of the particle diffusing in a long conical tube (the length of the tube is much greater than its smallest radius) are used to study reduction of the three-dimensional diffusion in tubes of varying cross section to an effective one-dimensional description. The authors find that the one-dimensional description in the form of the Fick-Jacobs equation with a position-dependent diffusion coefficient, D(x ), suggested by Zwanzig [J. Phys. Chem. 96, 3926 (1992)], with D(x ) given by the Reguera-Rubí formula [Phys. Rev. E 64, 061106 (2001)], D(x )=D/√1+R'(x)2, where D is the particle diffusion coefficient in the absence of constraints, and R(x ) is the tube radius at x, is valid when ∣R'(x)∣⩽1. When ∣R'(x)∣>1, higher spatial derivatives of the one-dimensional concentration in the effective diffusion equation cannot be neglected anymore as was indicated by Kalinay and Percus [J. Chem. Phys. 122, 204701 (2005)]. Thus the reduction to the effective one-dimensional description is a useful tool only when ∣R'(x)∣⩽1 since in this case one can apply the powerful standard methods to analyze the resulting diffusion equation.

  12. Dynamical effects of a one-dimensional multibarrier potential of finite range

    CERN Document Server

    Bar, D

    2002-01-01

    We discuss the properties of a large number N of one-dimensional (bounded) locally periodic potential barriers in a finite interval. We show that the transmission coefficient, the scattering cross section $\\sigma$, and the resonances of $\\sigma$ depend sensitively upon the ratio of the total spacing to the total barrier width. We also show that a time dependent wave packet passing through the system of potential barriers rapidly spreads and deforms, a criterion suggested by Zaslavsky for chaotic behaviour. Computing the spectrum by imposing (large) periodic boundary conditions we find a Wigner type distribution. We investigate also the S-matrix poles; many resonances occur for certain values of the relative spacing between the barriers in the potential.

  13. Effects of delayed nonlinear response on wave packet dynamics in one-dimensional generalized Fibonacci chains

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianxin; Zhang, Zhenjun [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Tong, Peiqing, E-mail: pqtong@njnu.edu.cn [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems, Nanjing Normal University, Nanjing 210023 (China)

    2013-07-15

    We investigate the spreading of an initially localized wave packet in one-dimensional generalized Fibonacci (GF) lattices by solving numerically the discrete nonlinear Schrödinger equation (DNLSE) with a delayed cubic nonlinear term. It is found that for short delay time, the wave packet is self-trapping in first class of GF lattices, that is, the second moment grows with time, but the corresponding participation number does not grow. However, both the second moment and the participation number grow with time for large delay time. This illuminates that the wave packet is delocalized. For the second class of GF lattices, the dynamic behaviors of wave packet depend on the strength of on-site potential. For a weak on-site potential, the results are similar to the case of the first class. For a strong on-site potential, both the second moment and the participation number does not grow with time in the regime of short delay time. In the regime of large delay time, both the second moment and the participation number exhibit stair-like growth.

  14. Wave-packet dynamics in one-dimensional nonlinear Schroedinger lattices: local vs. nonlocal nonlinear effects

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Phi [Central University of Construction, Tuy Hoa (Viet Nam); Kim, Ki Hong [Ajou University, Suwon (Korea, Republic of)

    2014-02-15

    We study numerically the dynamics of an initially localized wave packet in one-dimensional nonlinear Schroedinger lattices with both local and nonlocal nonlinearities. Using the discrete nonlinear Schroedinger equation generalized by including a nonlocal nonlinear term, we calculate four different physical quantities as a function of time, which are the return probability to the initial excitation site, the participation number, the root-mean-square displacement from the excitation site and the spatial probability distribution. We investigate the influence of the nonlocal nonlinearity on the delocalization to self-trapping transition induced by the local nonlinearity. In the non-self-trapping region, we find that the nonlocal nonlinearity compresses the soliton width and slows down the spreading of the wave packet. In the vicinity of the delocalization to self-trapping transition point and inside the self-trapping region, we find that a new kind of self-trapping phenomenon, which we call partial self-trapping, takes place when the nonlocal nonlinearity is sufficiently strong.

  15. Tailoring the morphology and wettability of ZnO one-dimensional nanostructures%ZnO一维纳米结构的形貌调控与亲疏水性研究

    Institute of Scientific and Technical Information of China (English)

    武祥; 蔡伟; 曲凤玉

    2009-01-01

    分别使用金属、半导体等类型的基片作沉积衬底,采用气相沉积的方法合成了多种ZnO一维纳米结构,如塔状结构、锥状结构、蘑菇状结构、环状结构等等.用扫描电镜,透射电镜等对合成产物的形貌和结构进行了研究,结果发现沉积衬底对合成产物形貌和结构有着重要的影响.同时对合成塔状纳米结构的生长机理做了系统地分析,并研究了其相应的亲疏水性能.%Diverse one-dimensional (1D)nanostructures of ZnO, such as tower-like, conical, mushroom-like and ring-like, have been synthesized through vapor phase deposition method using metals and semiconductors as the substrates. SEM and TEM are used to characterize the morphologies and microstructures of as-synthesized products. Results indicate that the substrates have important effect on the morphology and structure of as-synthesized products. The growth mechanism of as-grown tower-like nanostructure is explained and the corresponding wettability is studied.

  16. Ultracold bosons in a one-dimensional optical lattice chain: Newton's cradle and Bose enhancement effect

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ji-Guo; Yang, Shi-Jie, E-mail: yangshijie@tsinghua.org.cn

    2017-05-18

    We study a model to realize the long-distance correlated tunneling of ultracold bosons in a one-dimensional optical lattice chain. The model reveals the behavior of a quantum Newton's cradle, which is the perfect transfer between two macroscopic quantum states. Due to the Bose enhancement effect, we find that the resonantly tunneling through a Mott domain is greatly enhanced.

  17. Quantum Dynamics of One-Dimensional Nanocrystalline Solids

    Institute of Scientific and Technical Information of China (English)

    丁建文; 颜晓红; 曹觉先; 王登龙

    2002-01-01

    A novel ballistic-nonballistic dynamic transition in one-dimensional nanocrystalline solids is found upon varyingthe strength of the composition modulation and the grain-boundary effect. This can contribute to the under-standing of the strange electronic transport properties of nanostructured systems.

  18. Quantum dynamics of one-dimensional nanocrystalline solids

    CERN Document Server

    Ding Jian Wen; Cao Jue Xian; Wang Deng Long

    2002-01-01

    A novel ballistic-non-ballistic dynamic transition in one-dimensional nanocrystalline solids is found upon varying the strength of the composition modulation and the grain-boundary effect. This can contribute to the understanding of the strange electronic transport properties of nano-structured systems

  19. Electric-Field Effect on the Angle-Dependent Magnetotransport Properties of Quasi-One-Dimensional Conductors

    Science.gov (United States)

    Kobayashi, K.; Saito, M.; Ohmichi, E.; Osada, T.

    2006-03-01

    We report a novel electric field effect on angular dependent magnetotransport in quasi-one-dimensional layered conductors with a pair of sheetlike Fermi surfaces. Under tilted magnetic fields and additional interlayer electric fields, semiclassical electron orbits on two Fermi sheets become periodic at different magnetic field orientations. This causes double splitting of the Lebed’s commensurability resonance in interlayer transport, and the amount of splitting allows us to estimate the Fermi velocity directly. We have successfully demonstrated this effect in the organic conductor α-(BEDT-TTF)2KHg(SCN)4.

  20. Effective permittivity and permeability of one-dimensional dielectric photonic crystal within a band gap

    Institute of Scientific and Technical Information of China (English)

    Guo Ji-Yong; Chen Hong; Li Hong-Qiang; Zhang Ye-Wen

    2008-01-01

    We take a finite dielectric photonic crystal as a homogeneous slab and have extracted the effective parameters. Our systematic study shows that the effective permittivity or permeability of dielectric photonic crystal is negative within a band gap region. This means that the band gap might act as ε-negative materials (ENMs) with ε0, or μ-negative materials (MNMs) with ε>0 and μ<0. Moreover the effective parameters sensitively rely on size, surface termination, symmetry, etc. The effective parameters can be used to design full transmission tunnelling modes and amplify evanescent wave. Several cases are studied and the results show that dielectric photonic band gap can indeed mimic a single negative material (ENM or MNM) under some restrictions.

  1. Effects of Colored Noise on Periodic Orbits in a One-Dimensional Map

    Institute of Scientific and Technical Information of China (English)

    LI Feng-Guo; AI Bao-Quan

    2011-01-01

    Noise can induce inverse period-doubling transition and chaos. The effects of the colored noise on periodic orbits, of the different periodic sequences in the logistic map, are investigated. It is found that the dynamical behaviors of the orbits, induced by an exponentially correlated colored noise, are different in the mergence of transition, and the effects of the noise intensity on their dynamical behaviors are different from the effects of the correlation time of noise.Remarkably, the noise can induce new periodic orbits, namely, two new orbits emerge in the period-four sequence at the bifurcation parameter value μ = 3.5, four new orbits in the period-eight sequence at μ = 3.55, and three new orbits in the period-six sequence at μ = 3.846, respectively. Moreover, the dynamical behaviors of the new orbits clearly show the resonancelike response to the colored noise.

  2. Nonlinear frequency conversion effect in a one-dimensional graphene-based photonic crystal

    Science.gov (United States)

    Wicharn, S.; Buranasiri, P.

    2015-07-01

    In this research, the nonlinear frequency conversion effect based on four-wave mixing (FWM) principle in a onedimensional graphene-based photonics crystal (1D-GPC) has been investigated numerically. The 1D-GPC structure is composed of two periodically alternating material layers, which are graphene-silicon dioxide bilayer system and silicon membrane. Since, the third-order nonlinear susceptibility χ(3) of bilayer system is hundred time higher than pure silicon dioxide layer, so the enhancement of FWM response can be achieved inside the structure with optimizing photon energy being much higher than a chemical potential level (μ) of graphene sheet. In addition, the conversion efficiencies of 1DGPC structure are compared with chalcogenide based photonic structure for showing that 1D-GPC structure can enhance nonlinear effect by a factor of 100 above the chalcogenide based structure with the same structure length.

  3. A Model for One-Dimensional Coherent Synchrotron Radiation including Short-Range Effects

    CERN Document Server

    Ryne, Robert D; Qiang, Ji; Yampolsky, Nikolai

    2012-01-01

    A new model is presented for simulating coherent synchrotron radiation (CSR) in one dimension. The method is based on convolving an integrated Green function (IGF) with the longitudinal charge density. Since it is based on an IGF, the accuracy of this approach is determined by how well one resolves the charge density and not by resolving the single particle wake function. Since short-range wakefield effects are included analytically, the approach can be much more efficient than ordinary (non-IGF) approaches in situations where the wake function and charge density have disparate spatial scales. Two cases are presented: one derived from the full wake including short-range effects, and one derived from the asymptotic wake. In the latter case the algorithm contains the same physics as others based on the asymptotic approximation, but requires only the line charge density and not its derivative. Examples are presented that illustrate the limitations of the asymptotic-wake approximation, and that illustrate how mic...

  4. Coupling of effective one-dimensional two-level atoms to squeezed light

    CERN Document Server

    Clark, S; Clark, Stephen; Parkins, Scott

    2002-01-01

    A cavity QED system is analyzed which duplicates the dynamics of a two-level atom in free space interacting exclusively with broadband squeezed light. We consider atoms in a three or four-level Lambda-configuration coupled to a high-finesse optical cavity which is driven by a squeezed light field. Raman transitions are induced between a pair of stable atomic ground states via the squeezed cavity mode and coherent driving fields. An analysis of the reduced master equation for the atomic ground states shows that a three-level atomic system has insufficient parameter flexibility to act as an effective two-level atom interacting exclusively with a squeezed reservoir. However, the inclusion of a fourth atomic level, coupled dispersively to one of the two ground states by an auxiliary laser field, introduces an extra degree of freedom and enables the desired interaction to be realised. As a means of detecting the reduced quadrature decay rate of the effective two-level system, we examine the transmission spectrum o...

  5. Resonant tunneling effect in one-dimensional twinned lattice photonic crystal under total reflection conditions

    Science.gov (United States)

    Feng, Xi; Li, Hu; Yuxia, Tang

    2016-07-01

    Under total reflection conditions, it typically seems as though light waves will be reflected completely on the interface; in actuality, the waves can penetrate the medium as evanescent waves. In this paper, we present a twinned lattice photonic crystal with a unit cell composed of AB layers and their mirror. We assume that the refractive index n 0 of the input and output end is equal to n B and larger than n A . We first demonstrate the dependence of band structure on the incidence angle and normalized wavelength, in which the resonant tunneling bands are exposed. We then draw a comparison of bands between ABBA and AB. To conclude, we discuss the resonant tunneling effect in the twinned lattice photonic crystal under the total reflection conditions. As incidence angle increases, the resonant tunneling band ultimately vanishes completely.

  6. Research progress in growth of one-dimensional ZnO nanostructures and preparing methods of related devices%一维氧化锌纳米结构生长及器件制备研究进展

    Institute of Scientific and Technical Information of China (English)

    秦杰明; 田立飞; 赵东旭; 蒋大勇; 曹建明; 丁梦; 郭振

    2011-01-01

    Morphologies of one-dimensional ZnO nanostructures(nanowires,nanobelts,etc.) and their characteristics are introduced.Methods of growing one-dimensional ZnO nanostructures and the relevant devices are demonstrated comprehensively,e.g.hydrothermal and chemical vapor deposition and so on.Progress in applications including light-emitting diodes and nanogenerators is provided.Finally,the future developing trend of one-dimensional ZnO nanostructures is presented and some novel means,techniques,etc.are also proposed.%介绍了一维氧化锌(ZnO)纳米结构的形态(纳米线和纳米带等)及其特点,阐述了该结构生长及器件制备的方法,例如水热法和化学气相沉积法等.概述了该结构在发光二极管和纳米发电机等方面的应用进展.最后,对一维ZnO纳米结构的未来发展趋势进行了展望,并在新方法和新工艺等方面提出了一些建议.

  7. Assessing the applicability of the reduction to effective one-dimensional description of diffusion in a hemispherical shaped tube

    Science.gov (United States)

    Vázquez, Marco-Vinicio; Dagdug, Leonardo

    2010-12-01

    Computer simulations of the diffusion of a Brownian particle, in a hemispherical shaped tube, were carried out to assess the range of applicability of the reduction of the three-dimensional diffusion to an effective one-dimensional description. Previously Berezhkovskii et al. [21] founded that the one-dimensional description centered in the Fick-Jacobs' equation with a position dependent diffusion coefficients, D(x) (one due to R. Zwanzig [14], and another by Reguera-Rubí [15]), has a restricted range of applicability, for a conical tube. Remarkably, our results have shown that applying the Zwanzig's formula one can predict variation of τ in the whole range of a/R in n→w direction, while the Reguera-Rubí's formula fits simulations' data in the w→n direction. This is an important result since it is known that Reguera-Rubí's predicts better the mean first-passage time's behavior without regard of direction in other geometries, and this is our principal result.

  8. Impurity effect on entanglement asymptotic state in one-dimensional Ising system coupled to a dissipative environment

    Science.gov (United States)

    Sadiek, G.

    2017-07-01

    We consider a finite one-dimensional Ising spin chain under the influence of a dissipative Lindblad environment obeying the Born-Markovian constrain in presence of an external magnetic field with open boundary conditions. We study the effect of a single impurity, located at the terminal or center of the chain, on the time evolution and asymptotic steady state of the bipartite entanglement in the chain starting from a maximally entangled initial state. We found that the impurity has a significant effect on the bipartite entanglement of its nearest spins and can be used to tune their steady state value but has almost no noticeable impact on the far ones. At finite temperature, the thermal excitations suppress the dynamics of the system and reduce the value of the steady state and may completely wipe it out as the temperature is increased, which eliminates the effect of the impurity in that case.

  9. Quantum Hall Effect in Quasi-One-Dimensional Conductors: The Roles of Moving FISDW, Finite Temperature, and Edge States

    Science.gov (United States)

    Yakovenko, Victor M.; Goan, Hsi-Sheng

    1996-12-01

    This paper reviews recent developments in the theory of the quantum Hall effect (QHE) in the magnetic-field-induced spin-density-wave (FISDW) state of the quasi-one-dimensional organic conductors (TMTSF)2X. The origin and the basic features of the FISDW are reviewed. The QHE in the pinned FISDW state is derived in several simple, transparent ways, including the edge states formulation of the problem. The temperature dependence of the Hall conductivity is found to be the same as the temperature dependence of the Fröhlich current. It is shown that, when the FISDW is free to move, it produces an additional contribution to the Hall conductivity that nullifies the total Hall effect. The paper is written on mathematically simple level, emphasizes physical meaning over sophisticated mathematical technique, and uses inductive, rather than deductive, reasoning.

  10. One-dimensional turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Kerstein, A.R. [Sandia National Lab., Livermore, CA (United States)

    1996-12-31

    One-Dimensional Turbulence is a new turbulence modeling strategy involving an unsteady simulation implemented in one spatial dimension. In one dimension, fine scale viscous and molecular-diffusive processes can be resolved affordably in simulations at high turbulence intensity. The mechanistic distinction between advective and molecular processes is thereby preserved, in contrast to turbulence models presently employed. A stochastic process consisting of mapping {open_quote}events{close_quote} applied to a one-dimensional velocity profile represents turbulent advection. The local event rate for given eddy size is proportional to the velocity difference across the eddy. These properties cause an imposed shear to induce an eddy cascade analogous in many respects to the eddy cascade in turbulent flow. Many scaling and fluctuation properties of self-preserving flows, and of passive scalars introduced into these flows, are reproduced.

  11. Enhanced four-wave-mixing effects by large group indices of one-dimensional silicon photonic crystal waveguides.

    Science.gov (United States)

    Kim, Dong Wook; Kim, Seung Hwan; Lee, Seoung Hun; Jong, Heung Sun; Lee, Jong-Moo; Lee, El-Hang; Kim, Kyong Hon

    2013-12-02

    Enhanced four-wave-mixing (FWM) effects have been observed with the help of large group-indices near the band edges in one-dimensional (1-D) silicon photonic crystal waveguides (Si PhCWs). A significant increase of the FWM conversion efficiency of about 17 dB was measured near the transmission band edge of the 1-D PhCW through an approximate 3.2 times increase of the group index from 8 to 24 with respect to the central transmission band region despite a large group-velocity dispersion. Numerical analyses based on the coupled-mode equations for the degenerated FWM process describe the experimentally measured results well. Our results indicate that the 1-D PhCWs are good candidates for large group-index enhanced nonlinearity devices even without having any special dispersion engineering.

  12. Radio signal propagation effects in a nonstationary ionosphere based on the numerical solution of the one-dimensional wave equation

    Science.gov (United States)

    Laryunin, O. A.

    2016-09-01

    The goal of this work is to solve Maxwell equations analytically and numerically in a one-dimensional case under the conditions of a nonstationary medium. Analytical solutions to the Maxwell equations have been obtained in two partial cases of the linear and quadratic time dependence of medium permittivity. Since the number of models for which the wave equation can be solved analytically is limited, it becomes also necessary to apply numerical methods, specifically the method of finite differences, in a time domain Finite Difference Time Domain method. The effects of the decameter wave dynamic reflection from structures with considerable spatial gradients (the scales of which are comparable with the sounding pulse wavelength) have been studied based on this method. It has been shown that the spectrum can broaden and a Doppler frequency shift of a reflected signal can originate can take place.

  13. Phase statistics of light wave reflected from one-dimensional optical disordered media and its effects on light transport properties

    CERN Document Server

    Pradhan, Prabhakar

    2015-01-01

    Light wave reflection from optical disordered media is always associate with its phase, and the phase statistics influence the reflection statistics. We report a detailed numerical study of the statistics of the reflection coefficient RR* and its associated phase(theta) for plane electromagnetic waves reflected from one dimensional (1D) Gaussian white-noise optical disordered media, ranging from weak to strong disordered regimes. We solve numerically the full Fokker-Planck (FP) equation for the joint probability distribution in the RR* - phase(theta) space for different lengths of the sample with different disorder strengths. The statistical optical transport properties of 1D optical disordered media are calculated using the full FP equation numerically. This constitutes a complete solution for the reflection phase statistics and its effects on light transport properties in a 1D Gaussian white-noise disordered optical potentials. Our results show the regime of the validation of the random phase approximations...

  14. Response of a particle in a one-dimensional lattice to an applied force: Dynamics of the effective mass

    CERN Document Server

    Duque-Gomez, Federico

    2012-01-01

    We study the behaviour of the expectation value of the acceleration of a particle in a one-dimensional periodic potential when an external homogeneous force is suddenly applied. The theory is formulated in terms of modified Bloch states that include the interband mixing induced by the force. This approach allows us to understand the behaviour of the wavepacket, which responds with a mass that is initially the bare mass, and subsequently oscillates around the value predicted by the effective mass. If Zener tunneling can be neglected, the expression obtained for the acceleration of the particle is valid over timescales of the order of a Bloch oscillation, which are of interest for experiments with cold atoms in optical lattices. We discuss how these oscillations can be tuned in an optical lattice for experimental detection.

  15. Magneto-electrical transport through MBE-grown III-V semiconductor nanostructures. From zero- to one-dimensional type of transport

    Energy Technology Data Exchange (ETDEWEB)

    Storace, Eleonora

    2009-07-08

    From the development of the first transistor in 1947, great interest has been directed towards the technological development of semiconducting devices and the investigation of their physical properties. A very vital field within this topic focuses on the electrical transport through low-dimensional structures, where the quantum confinement of charge carriers leads to the observation of a wide variety of phenomena that, in their turn, can give an interesting insight on the fundamental properties of the structures under examination. In the present thesis, we will start analyzing zero-dimensional systems, focusing on how electrons localized onto an island can take part in the transport through the whole system; by precisely tuning the tunnel coupling strength between this island and its surroundings, we will then show how it is possible to move from a zero- to a one-dimensional system. Afterwards, the inverse path will be studied: a one-dimensional system is electrically characterized, proving itself to split up due to disorder into several zero-dimensional structures. (orig.)

  16. Investigation of magneto-optical effects on properties of surface modes in one dimensional magnetized plasma photonic crystals

    Science.gov (United States)

    Shukla, Shikha; Prasad, Surendra; Singh, Vivek

    2016-09-01

    We have studied the properties of surface modes on one dimensional magnetized plasma photonic crystals in two configurations: Faraday and Voigt configurations. The results have been demonstrated by using the transfer matrix method and employing boundary conditions for TE and TM modes, respectively. For the Voigt effect, only the TM mode is considered because the TE modes under the influence of external magnetic field have the same properties as un-magnetized plasma. The influence of external magnetic field has been studied for three cases, i.e., TE left circular polarization, TE right circular polarization, and TM surface modes. It is shown that the properties of surface modes can be tuned correspondingly by changing the cap layer thickness, wave vector, and external magnetic field in the desired photonic band gap. The results show that collision frequency has a negligible effect on surface modes. A new type of wave called Fano mode has been reported for the Voigt effect for the TM mode in the first band gap. Proof of its existence has been demonstrated in the present paper.

  17. Effect of presence of benzene ring in surfactant hydrophobic chain on the transformation towards one dimensional aggregate

    Directory of Open Access Journals (Sweden)

    Rabah A. Khalil

    2015-07-01

    Full Text Available The formation of wormlike micelle and the following significant changes in rheological properties suffer misunderstanding from both theoretical and fundamental aspects. Recently, we have introduced a theory for interpreting such important phenomenon which is referred to as critical intermolecular forces (CIF. The theory has stated that the hydrophobic effect is the main factor for the formation of worm-like aggregates. Therefore, it seems interesting to check out the validity of this new physical insight through investigating the presence of benzene ring as less hydrophobic group in contrast to that of alkyl in surfactant tail. The mixture of anionic sodium dodecylbenzenesulphonate (SDBS and cationic cetyltrimethylammonium bromide (CTAB shows a high dynamic viscosity peak at the ratio of 80/20 of 3 wt.% CTAB/SDBS indicating the formation of wormlike micelles. The thermodynamic properties have been evaluated for this mixture exhibiting good agreement with the rheological changes. Interestingly, the results show the presence of benzene ring (in SDBS causing a negative effect towards the formation of one dimensional aggregate in contrast to previous results which support the proposed CIF theory. The presence of nonionic surfactant TritonX-100 in binary and ternary systems of SDBS and CTAB prohibits the formation of wormlike micelles.

  18. Effects of temperature dependence of electrical and thermal conductivities on the Joule heating of a one dimensional conductor

    Science.gov (United States)

    Antoulinakis, F.; Chernin, D.; Zhang, Peng; Lau, Y. Y.

    2016-10-01

    We examine the effects of temperature dependence of the electrical and thermal conductivities on Joule heating of a one-dimensional conductor by solving the coupled non-linear steady state electrical and thermal conduction equations. The spatial temperature distribution and the maximum temperature and its location within the conductor are evaluated for four cases: (i) constant electrical conductivity and linear temperature dependence of thermal conductivity, (ii) linear temperature dependence of both electrical and thermal conductivities, (iii) the Wiedemann-Franz relation for metals, and (iv) polynomial fits to measured data for carbon nanotube fibers and for copper. For (i) and (ii), it is found that there are conditions under which no steady state solution exists, which may indicate the possibility of thermal runaway. For (i), analytical solutions are constructed, from which explicit expressions for the parameter bounds for the existence of steady state solutions are obtained. The shifting of these bounds due to the introduction of linear temperature dependence of electrical conductivity (case (ii)) is studied numerically. These results may provide guidance in the design of circuits and devices in which the effects of coupled thermal and electrical conduction are important.

  19. Characterization of domain structure in one-dimensional SrRuO{sub 3} nanostructure using synchrotron x-ray microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Imai, Yasuhiko, E-mail: imai@spring8.or.jp [Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Sayo, Hyogo 679-5198 Japan (Japan); Kimura, Shigeru [Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Sayo, Hyogo 679-5198 Japan (Japan); Japan Science and Technology Agency, CREST, Uji, Kyoto 611-0011 (Japan); Kan, Daisuke; Shimakawa, Yuichi [Japan Science and Technology Agency, CREST, Uji, Kyoto 611-0011 (Japan); Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    2016-07-27

    SrRuO{sub 3} (SRO) thin films with a geometric shape of one-dimensional stripes can be epitaxially grown on a SrTiO{sub 3} (STO) substrate. Conventional X-ray reciprocal space map (RSM) measurements revealed that the stripes consist of multiple crystallographic domains. We performed synchrotron X-ray microdiffraction measurements to determine whether the single stripe of the SRO has a single crystallographic domain or not. Spacing between stripes is ~200 nm that is comparable to a beam size available for the microdiffraction. The synchrotron X-ray microdiffraction experiment was performed at BL13XU, SPring-8. RSMs of asymmetric diffractions around STO 204 reflection were measured by a broad-beam (200 × 200 µm{sup 2}) and the sub-micro-beam (250(h) × 190(v) nm{sup 2}). Both SRO 260 and 620 are seen in the RSM measured by the broad-beam due to the crystallographic twinning. On the other hand, only SRO 620 is observed in the RSM measured by the sub-micro-beam. The result shows the domain length of the single stripe SRO thin film is longer than the vertical beam size of 190 nm.

  20. Effective multidimensional crossover behavior in a one-dimensional voter model with long-range probabilistic interactions

    Science.gov (United States)

    Rodriguez, D. E.; Bab, M. A.; Albano, E. V.

    2011-01-01

    A variant of the standard voter model, where a randomly selected site of a one-dimensional lattice (d=1) adopts the state of another site placed at a distance r from the previous one, is proposed and studied by means of numerical simulations that are rationalized with the aid of dynamical and finite-size scaling arguments. The distance between the two sites is also selected randomly with a probability given by P(r)∝r-(d+σ), where σ is a control parameter. In this way one can study how the introduction of these long-range interactions influences the dynamic behavior of the standard voter model with nearest-neighbor interactions. It is found that the dynamics strongly depends on the range of the interactions, which is parameterized by σ, leading to an interesting effective multidimensional crossover behavior, as follows. (a) For σ2, as well as the case of both scale-free and small-world networks. (b) For σ>1, an ordering dynamics is observed, such that ρ(t)∝t-α, where the exponent α increases with σ until it reaches the value α=1/2 for σ⩾5, which corresponds to the behavior of the standard voter model with short-range interactions in d=1. (c) Finally, for σ≈1 we show evidence of a critical-type behavior as in the case of the critical dimension (dc=2) of the standard voter model.

  1. Effects of Bond Alternation on the Ground-State Phase Diagram of One-Dimensional XXZ Model

    Institute of Scientific and Technical Information of China (English)

    QIANG Ling; LIU Guang-Hua; TIAN Guang-Shan

    2013-01-01

    The ground-state properties and quantum phase transitions (QPTs) of the one-dimensional bond-alternative XXZ model are investigated by the infinite time-evolving block decimation (iTEBD) method.The bond-alternative effects on its ground-state phase diagram are discussed in detail.Once the bond alternation is taken into account,the antiferromagnetic phase (△ > 1) will be destroyed at a given critical point and change into a disordered phase without nonlocal string order.The QPT is shown to be second-order,and the whole phase diagram is provided.For the ferromagnetic phase region (△ <-1),the critical point rc always equals 1 (independent of △),and the QPT for this case is shown to be first-order.The dimerized Heisenberg model is also discussed,and two disordered phases can be distinguished by with or without nonlocal string orders.Both the bipartite entanglement and the fidelity per site,as two kinds of model-independent measures,are capable of describing all the QPTs in such a quantum model.

  2. Effect of double local quenches on the Loschmidt echo and entanglement entropy of a one-dimensional quantum system

    Science.gov (United States)

    Rajak, Atanu; Divakaran, Uma

    2016-04-01

    We study the effect of two simultaneous local quenches on the evolution of the Loschmidt echo (LE) and entanglement entropy (EE) of a one dimensional transverse Ising model. In this work, one of the local quenches involves the connection of two spin-1/2 chains at a certain time and the other corresponds to a sudden change in the magnitude of the transverse field at a given site in one of the spin chains. We numerically calculate the dynamics associated with the LE and the EE as a result of such double quenches, and discuss the various timescales involved in this problem using the picture of quasiparticles (QPs) generated as a result of such quenches. We perform a detailed analysis of the probability of QPs produced at the two sites and the nature of the QPs in various phases, and obtain interesting results. More specifically, we find partial reflection of these QPs at the defect center or the site of h-quench, resulting in new timescales which have never been reported before.

  3. Optical waveguide behavior of Se-doped and undoped CdS one-dimensional nanostructures using near-field optical microscopy

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao; LIU Dan; PAN Anlian; FANG Zheyu; HUANG Shan; ZHU Xing

    2009-01-01

    The optical waveguide behaviors of CdS and CdSxSe1-x nanostructures are studied using near-field optical microscopy. Optical measurements demonstrate that light may be guided on sub-wavelength scales along CdS nanoribbons in straight or bent structures. The photoluminescence (PL) spectra from nanoribbon emission using scanning near-field optical microscopy are analyzed under different inci-dent laser intensities. The PL spectra along Se-doped and undoped CdS nanoribbons at different propagation distances are investigated. Both the guided PL spectra of Se-doped and undoped CdS nanoribbons show red-shifts because of the band-edge absorption. Our results are useful for the de-velopment of new kinds of functional nano devices.

  4. Optical waveguide behavior of Se-doped and undoped CdS one-dimensional nanostructures using near-field optical microscopy

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The optical waveguide behaviors of CdS and CdSxSe1?x nanostructures are studied using near-field optical microscopy. Optical measurements demonstrate that light may be guided on sub-wavelength scales along CdS nanoribbons in straight or bent structures. The photoluminescence (PL) spectra from nanoribbon emission using scanning near-field optical microscopy are analyzed under different incident laser intensities. The PL spectra along Se-doped and undoped CdS nanoribbons at different propagation distances are investigated. Both the guided PL spectra of Se-doped and undoped CdS nanoribbons show red-shifts because of the band-edge absorption. Our results are useful for the development of new kinds of functional nano devices.

  5. A one-dimensional semi-empirical model considering transition boiling effect for dispersed flow film boiling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu-Jou [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Pan, Chin, E-mail: cpan@ess.nthu.edu.tw [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Low Carbon Energy Research Center, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China)

    2017-05-15

    Highlights: • Seven heat transfer mechanisms are studied numerically by the model. • A semi-empirical method is proposed to account for the transition boiling effect. • The parametric effects on the heat transfer mechanisms are investigated. • The thermal non-equilibrium phenomenon between vapor and droplets is investigated. - Abstract: The objective of this paper is to develop a one-dimensional semi-empirical model for the dispersed flow film boiling considering transition boiling effects. The proposed model consists of conservation equations, i.e., vapor mass, vapor energy, droplet mass and droplet momentum conservation, and a set of closure relations to address the interactions among wall, vapor and droplets. The results show that the transition boiling effect is of vital importance in the dispersed flow film boiling regime, since the flowing situation in the downstream would be influenced by the conditions in the upstream. In addition, the present paper, through evaluating the vapor temperature and the amount of heat transferred to droplets, investigates the thermal non-equilibrium phenomenon under different flowing conditions. Comparison of the wall temperature predictions with the 1394 experimental data in the literature, the present model ranging from system pressure of 30–140 bar, heat flux of 204–1837 kW/m{sup 2} and mass flux of 380–5180 kg/m{sup 2} s, shows very good agreement with RMS of 8.80% and standard deviation of 8.81%. Moreover, the model well depicts the thermal non-equilibrium phenomenon for the dispersed flow film boiling.

  6. One-dimensional fossil-like γ-Fe2O3@carbon nanostructure: preparation, structural characterization and application as adsorbent for fast and selective recovery of gold ions from aqueous solution

    Science.gov (United States)

    Gunawan, Poernomo; Xiao, Wen; Hao Chua, Marcus Wen; Poh-Choo Tan, Cheryl; Ding, Jun; Zhong, Ziyi

    2016-10-01

    One-dimensional (1D) magnetic nanostructures with high thermal stability have important industrial applications, but their fabrication remains a big challenge. Herein we demonstrate a scalable approach for the preparation of stable 1D γ-Fe2O3@carbon, which is also applicable for other metal oxide-core and carbon-shell nanostructures, such as 1D TiO2@carbon. One-dimensional ferric oxyhydroxide (α-FeO(OH)) was initially prepared by a hydrothermal method, followed by carbon coating through hydrothermal treatment of the resulting metal oxide in glucose solution. After calcination in N2 gas at 500 °C and subsequent exposure to air, the initial carbon-coated 1D α-Fe2O3 was converted to 1D γ-Fe2O3@carbon, which was very stable without any observed changes even after 1.5 years of storage under ambient conditions. The materials were then used as adsorbents and found to be highly selective towards Au (III) adsorption, of which the maximum adsorption capacity is about 600 mg Au/g sorbent (1132 mg Au/g carbon). The spent sorbent containing Au after adsorption can be readily collected by applying a magnetic field due to the presence of the magnetic core, and the adsorbed Au particles are subsequently recovered after the combustion and dissolution of the sorbent. This work demonstrates not only a facile approach to the fabrication of robust 1D magnetic materials with a stable carbon shell, but also a possible cyanide-free process for the fast and selective recovery of gold from electronic waste and industrial water.

  7. Effect of Fabry-Perot resonances in disordered one-dimensional array of alternating dielectric bi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Luna-Acosta, G.A. [Instituto de Fisica, Universidad Autonoma de Puebla, Apartado Postal J-48, Puebla, Pue., 72570 (Mexico); Makarov, N.M. [Instituto de Ciencias, Universidad Autonoma de Puebla, Priv. 17 Norte No 3417, Col. San Miguel Hueyotlipan, Puebla, Pue., 72050 (Mexico)

    2009-12-15

    We study numerically and analytically the role of Fabry-Perot resonances in the transmission through a one-dimensional finite array formed by two alternating dielectric slabs. The disorder consists in varying randomly the width of one type of layers while keeping constant the width of the other type. Our numerical simulations show that localization is strongly inhibited in a wide neighborhood of the Fabry-Perot resonances. Comparison of our numerical results with an analytical expression for the average transmission, derived for weak disorder and finite number of cells, reveals that such expression works well even for medium disorder up to a certain frequency. Our results are valid for photonic and phononic one-dimensional disordered crystals, as well as for semiconductor superlattices. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  8. Designing a New Class of Electrocatalysts for Polymer Electrolyte Membrane Fuel Cells: Probing Size, Composition, and Structure Dependent Electrocatalytic Performance in High-Quality, One-Dimensional Noble Metal Nanostructures

    Science.gov (United States)

    Koenigsmann, Christopher

    A key challenge in the practical commercialization of PEMFCs is the extremely high cost and relatively poor durability of carbon supported Pt nanoparticle (Pt NP/C) electrocatalysts utilized in both the anode and cathode half-cells. Herein, we synthesize and characterize a new class of high-quality one-dimensional noble metal nanostructures as a potentially new and promising structural paradigm for the next generation of electrocatalyst materials. Specifically, we investigate the nature of the complex interplay amongst size, chemical composition, and electrocatalytic performance in high-quality elemental and bimetallic 1D noble metal nanowire systems with an emphasis on achieving efficient and sustainable methods for catalyst preparation. In terms of nanowire dimensions and composition, an interesting and measureable size-dependent enhancement in performance emerges in the case of elemental Pt, Pd, and Pd1-xAux nanowires possessing diameters ranging from the submicron (d = ˜200 nm) to the ultrathin regime (d = ˜1 nm). In a similar context, we have considered the role of chemical composition in 1D electrocatalysts and noted significant composition-dependent enhancements in activity and durability in high-quality, bimetallic Pd1-xAux and Pd1-xPtx NWs. A key finding that is apparent from these experimental results is that widely seen behavioral trends in the composition- and size-dependent performance for 0D nanoparticle-based catalysts do not hold in the case of 1D architectures, because of the patently unique structural and electronic effects, associated with their anisotropic structures. As a culmination of our efforts to take advantage of these intrinsic structure-activity correlations, our group has developed a morphology-, size-, and composition-optimized Pd9Au NW possessing a Pt monolayer shell (PtML˜Pd9Au NWs) electrocatalyst with an ultrathin 2 nm diameter, which yielded outstanding Pt mass and platinum group metal activities of 2.56 A/mgPt and 0.64 A

  9. One-Dimensionality and Whiteness

    Science.gov (United States)

    Calderon, Dolores

    2006-01-01

    This article is a theoretical discussion that links Marcuse's concept of one-dimensional society and the Great Refusal with critical race theory in order to achieve a more robust interrogation of whiteness. The author argues that in the context of the United States, the one-dimensionality that Marcuse condemns in "One-Dimensional Man" is best…

  10. One-Dimensionality and Whiteness

    Science.gov (United States)

    Calderon, Dolores

    2006-01-01

    This article is a theoretical discussion that links Marcuse's concept of one-dimensional society and the Great Refusal with critical race theory in order to achieve a more robust interrogation of whiteness. The author argues that in the context of the United States, the one-dimensionality that Marcuse condemns in "One-Dimensional Man" is best…

  11. Numerical analysis of temperature and flow effects in a dry, one-dimensional aquifer used for compressed air energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Smith, G.C.; Wiles, L.E.; Loscutoff, W.V.

    1979-02-01

    A detailed description of the method of analysis and the results obtained for an investigation of the hydrodynamic and thermodynamic response of a model of a dry porous media reservoir used for compressed air energy storage (CAES) is presented. Results were obtained from a one-dimensional simulation of the cycling of heated air to and from a radial flow field surrounding a single well in a porous rock. It was assumed that the performance of the bulk of the reservoir could be characterized by the performance of a single well.

  12. One-Dimensional Nanostructures for Neutron Detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yong [North Carolina State Univ., Raleigh, NC (United States); Eapen, Jacob [North Carolina State Univ., Raleigh, NC (United States); Hawari, Ayman [North Carolina State Univ., Raleigh, NC (United States)

    2015-05-04

    This report consists of four parts in addition to a publication/presentation list. Part I is on electronic structure simulations on boron nitride (BN) and BCxN nanotubes using density function theory (DFT), Part II is on fabrication and characterization of nanowire sensors, Part III is on irradiation response of BN nanotubes using molecular dynamics (MD) simulations, and Part IV is on the in-situ transmission electron microscopy (TEM) study of irradiation response of BN nanotubes.

  13. Linear and nonlinear optical response of one-dimensional semiconductors: finite-size and Franz–Keldysh effects

    Science.gov (United States)

    Bonabi, Farzad; Pedersen, Thomas G.

    2017-04-01

    The dipole moment formalism for the optical response of finite electronic structures breaks down in infinite ones, for which a momentum-based method is better suited. Focusing on simple chain structures, we compare the linear and nonlinear optical response of finite and infinite one-dimensional semiconductors. This comparison is then extended to cases including strong electro-static fields breaking translational invariance. For large electro-static fields, highly non-perturbative Franz–Keldysh (FK) features are observed in both linear and nonlinear spectra. It is demonstrated that dipole and momentum formalisms agree in the limit of large structures provided the intraband momentum contributions are carefully treated. This convergence is established even in the presence of non-perturbative electro-static fields.

  14. Electron-phonon interaction effect on persistent current in a one-dimensional quantum ring by using a simple model

    Science.gov (United States)

    Omidi, Mahboubeh; Faizabadi, Edris

    2015-09-01

    We use a simple model to study the electron-phonon interaction influences on persistent current in a one-dimensional quantum ring enclosed by a magnetic flux. With increasing the temperature, persistent current amplitude is reduced, especially in a quantum ring with two ions per primitive cell (diatomic ring) because of the participation of optical phonons. Furthermore, the periodicity of the Aharonov-Bohm oscillations changes to Φ0 / 2 (Φ0 is magnetic flux quantum). In a diatomic ring, by increasing the difference between left and right nearest-neighbor hopping integrals at zero temperature, persistent current variations show a transition from metallic to insulator against distinctive behavior at nonzero temperature.

  15. Giant Nernst effect and bipolarity in the quasi-one-dimensional metal Li0.9Mo6O17.

    Science.gov (United States)

    Cohn, J L; White, B D; dos Santos, C A M; Neumeier, J J

    2012-02-03

    The Nernst coefficient for the quasi-one-dimensional metal, Li{0.9}Mo{6}O{17}, is found to be among the largest known for metals (ν≃500  μV/KT at T∼20  K), and is enhanced in a broad range of temperature by orders of magnitude over the value expected from Boltzmann theory for carrier diffusion. A comparatively small Seebeck coefficient implies that Li{0.9}Mo{6}O{17} is bipolar with large, partial Seebeck coefficients of opposite sign. A very large thermomagnetic figure of merit, ZT∼0.5, is found at high field in the range T≈35-50  K.

  16. Properties of Ternary One Dimensional Plasma Photomic Crystals for an Obliquely Incident Electromagnetic Wave Considering the Effect of Collisions in Plasma Layers

    Institute of Scientific and Technical Information of China (English)

    S. PRASAD; Vivek SINGH; A. K. SINGH

    2012-01-01

    An analytical study is presented on the modal dispersion characteristics, group velocity, and effective group, as well as the phase index of a ternary one dimensional plasma photonic crystal for an obliquely incident electromagnetic wave considering the effect of collisions in plasma layers. The dispersion relation is derived by using the transfer matrix method and the boundary conditions based on electromagnetic theory. The dispersion curves are plotted for both the normal photonic band gap structure and the absorption photonic band gap structure. It is found that the increase in the angle of incidence shifts the photonic band gap toward higher frequencies. Also, the cutoff frequency is independent of collisions.

  17. Optical investigation of the one-dimensional confinement effects in narrow GaAs/GaAlAs quantum wires

    Science.gov (United States)

    Birotheau, L.; Izrael, A.; Marzin, J. Y.; Azoulay, R.; Thierry-Mieg, V.; Ladan, F. R.

    1992-12-01

    We show optical data obtained at 8 K on narrow GaAs/GaAlAs quantum wires, with width down to 15 nm, fabricated by reactive ion etching and metal organic chemical vapor deposition overgrowth. Lateral confinement energies (up to 23 meV) and polarization effects are evidenced in the photoluminescence excitation spectra. These experimental results are in good agreement with calculated absorption spectra, which include the effects of wire width fluctuations, yielding, for our fabrication technique, a value of ±5 nm for these size fluctuations.

  18. On the unambiguous determination of effective optical properties of periodic metamaterials: a one-dimensional case study

    DEFF Research Database (Denmark)

    Mortensen, Asger; Yan, Min; Sigmund, Ole

    2010-01-01

    We show how branch ambiguities in the extraction of effective parameters is arising as a direct consequence of the underlying Bloch state physics. The mutual importance of the different branches in general depends on the experimental context, and we show how the Fourier spectrum of the field inside...

  19. The effects of one-dimensional migration of self-interstitial clusters on the formation of void lattices

    DEFF Research Database (Denmark)

    Heinisch, H.L.; Singh, B.N.

    2002-01-01

    A series of kinetic Monte Carlo computer experiments performed on idealized systems clearly reveals the dramatic effects of 1-D migration of self-interstitial atom (SIA) crowdion clusters on the stability of void lattices. In the presence of migrating SIA, void lattices are shown to be unstable u...

  20. An investigation of dopping profile for a one dimensional heterostructure

    Science.gov (United States)

    Huang, Zhaohui

    2005-03-01

    A one-dimensional junction is formed by joining two silicon nanowires whose surfaces are terminated with capping groups of different electronegativity and polarizability. If this heterostructure is doped (with e.g. phosphorous) on the side with the higher bandgap, the system becomes a modulation doped heterostructure with novel one-dimensional electrostatics. We use density functional theory calculations in the pseudopotential approximation, plus empirical model calculations, to investigate doping profiles in this new class of nanostructures.

  1. THE STUDY OF THERMAL EFFECTS AND DEFECT MODE PROPERTIES ON THE ONE-DIMENSIONAL PHONONIC BAND GAP STRUCTURES

    Directory of Open Access Journals (Sweden)

    Arafa H. Aly

    2014-03-01

    Full Text Available In the present work, we describe an efficient study of the stop-band/pass-band dispersive behavior of 1D phononic crystal. We have treated the propagation and localization of in-plane (P and S/anti-plane (SH shear waves in perfect/defect phononic crystals. Based on the transfer matrix method and Bloch theory, the dispersion relations were calculated and plotted for both SH and in-plane waves. In order to confirm the results, the reflection coefficients were plotted for in-plane waves and compared with dispersion relations results. The effect of several parameters such as type and thickness of defect layer on the waves localization had be taken in account. Moreover, we have studied the effect of temperature on the phononic band gaps for SH and in-plane waves. These results can be useful in using phononic crystals as temperature sensor materials. Also, the presented analysis can be extended to acoustic filters and wave multiplexer.

  2. Effects of stoichiometry and substitution in quasi-one-dimensional iron chalcogenide BaFe2S3

    Science.gov (United States)

    Hirata, Yasuyuki; Maki, Sachiko; Yamaura, Jun-ichi; Yamauchi, Touru; Ohgushi, Kenya

    2015-11-01

    The effects of off-stoichiometry and elemental substitution on electronic properties of iron-based ladder compound BaFe2S3 are investigated. Resistivity and magnetization are revealed to be quite sensitive to the stoichiometry of Fe atoms, and 10% deficiency at Fe sites reduces the antiferromagnetic transition temperature by 40 K. The antiferromagnetic transition temperature decreases even faster and collapses to zero with hole doping through 10% K substitution at the Ba site, while the antiferromagnetic ordering phase remains with electron doping through 20% Co substitution at the Fe site. Such electron-hole asymmetry is opposite to two-dimensional iron-based superconductors, and can be explained on the basis of both itinerant and localized electronic pictures.

  3. Effects of negative index medium defect layers on the trans mission properties of one-dimensional photonic crystal

    Institute of Scientific and Technical Information of China (English)

    XIANG Yuan-jiang; DAI Xiao-yu; WEN Shuang-chun

    2007-01-01

    School of Computer and Communication, Hunan University, Changsha 410082, ChinaThe photonic band gap structure of 1D photonic crystal with a negative index medium defect layer is studied by using the transfer matrix method. Investigations show that the introdution of negative index medium defect layer and the increase of the negative index value will result in an extension of the band gap. Moreover, by increasing the negative index, the width of defect layer and the numbers of period photonic crystal, the width of defect modes will be narrowed, which is advantaged to obtain optical filters with narrow band. Finally, the effects of absorption on the properties of band gap and on defect modes have been discussed.

  4. General finite-size effects for zero-entropy states in one-dimensional quantum integrable models

    Science.gov (United States)

    Eliëns, Sebas; Caux, Jean-Sébastien

    2016-12-01

    We present a general derivation of the spectrum of excitations for gapless states of zero entropy density in Bethe ansatz solvable models. Our formalism is valid for an arbitrary choice of bare energy function which is relevant to situations where the Hamiltonian for time evolution differs from the Hamiltonian in a (generalized) Gibbs ensemble, i.e. out of equilibrium. The energy of particle and hole excitations, as measured with the time-evolution Hamiltonian, is shown to include additional contributions stemming from the shifts of the Fermi points that may now have finite energy. The finite-size effects are also derived and the connection with conformal field theory discussed. The critical exponents can still be obtained from the finite-size spectrum, however the velocity occurring here differs from the one in the constant Casimir term. The derivation highlights the importance of the phase shifts at the Fermi points for the critical exponents of asymptotes of correlations. We generalize certain results known for the ground state and discuss the relation to the dressed charge (matrix). Finally, we discuss the finite-size corrections in the presence of an additional particle or hole, which are important for dynamical correlation functions.

  5. One Dimensional Ballistic Electron Transport

    Directory of Open Access Journals (Sweden)

    Thomas K J

    2009-10-01

    Full Text Available Research in low-dimensional semiconductor systems over the last three decades has been largely responsible for the current progress in the areas of nanoscience and nanotechnology. The ability to control and manipulate the size, the carrier density, and the carrier type in two-, one-, and zero- dimensional structures has been widely exploited to study various quantum transport phenomena. In this article, a brief introduction is given to ballistic electron transport in one-dimensional quantum wires.

  6. One-dimensional InGaZnO field-effect transistor on a polyimide wire substrate for an electronic textile

    Science.gov (United States)

    Yoo, Tae-Hee; Sang, Byoung-In; Hwang, Do Kyung

    2016-02-01

    Amorphous InGaZnO (IGZO) is a promising semiconducting material to replace amorphous and polycrystalline Si. IGZO-based field-effect transistors (FET) can be versatile platforms for various electronic or optoelectronic applications. Here, we report on a one-dimensional (1-D) IGZO FET fabricated on a flexible polyimide wire substrate for electronic textiles (e-textiles). This flexible 1-D IGZO FET shows a high mobility of 18.18 cm2/Vs with a relatively good on/off current ratio of 104 at operating voltages below 5 V. Furthermore, a resistive-load inverter is implemented by connecting the 1-D IGZO FET to an external load resistor. Such an inverter exhibits obvious voltage switching characteristics, verifying the potential it is being a basic building block for an e-textile circuit system.

  7. Characterization by a time-frequency method of classical waves propagation in one-dimensional lattice : effects of the dispersion and localized nonlinearities

    CERN Document Server

    Richoux, Olivier; Hardy, Jean

    2009-01-01

    This paper presents an application of time-frequency methods to characterize the dispersion of acoustic waves travelling in a one-dimensional periodic or disordered lattice made up of Helmholtz resonators connected to a cylindrical tube. These methods allow (1) to evaluate the velocity of the wave energy when the input signal is an acoustic pulse ; (2) to display the evolution of the spectral content of the transient signal ; (3) to show the role of the localized nonlinearities on the propagation .i.e the emergence of higher harmonics. The main result of this paper is that the time-frequency methods point out how the nonlinearities break the localization of the waves and/or the filter effects of the lattice.

  8. One-Dimensional (1-D) Nanoscale Heterostructures

    Institute of Scientific and Technical Information of China (English)

    Guozhen SHEN; Di CHEN; Yoshio BANDO; Dmitri GOLBERG

    2008-01-01

    One-dimensional (1-D) nanostructures have been attracted much attention as a result of their exceptional properties, which are different from bulk materials. Among 1-D nanostructures, 1-D heterostructures with modulated compositions and interfaces have recently become of particular interest with respect to potential applications in nanoscale building blocks of future optoelectronic devices and systems. Many kinds of methods have been developed for the synthesis of 1-D nanoscale heterostructures. This article reviews the most recent development, with an emphasize on our own recent efforts, on 1-D nanoscale heterostructures, especially those synthesized from the vapor deposition methods, in which all the reactive precursors are mixed together in the reaction chamber. Three types of 1-D nanoscale heterostructures, defined from their morphologies characteristics, are discussed in detail, which include 1-D co-axial core-shell heterostructures, 1-D segmented heterostructures and hierarchical heterostructures. This article begins with a brief survey of various methods that have been developed for synthesizing 1-D nanoscale heterostructures and then mainly focuses on the synthesis, structures and properties of the above three types of nanoscale heterostructures. Finally, this review concludes with personal views towards the topic of 1-D nanoscale heterostructures.

  9. Flexible heat-flow sensing sheets based on the longitudinal spin Seebeck effect using one-dimensional spin-current conducting films.

    Science.gov (United States)

    Kirihara, Akihiro; Kondo, Koichi; Ishida, Masahiko; Ihara, Kazuki; Iwasaki, Yuma; Someya, Hiroko; Matsuba, Asuka; Uchida, Ken-ichi; Saitoh, Eiji; Yamamoto, Naoharu; Kohmoto, Shigeru; Murakami, Tomoo

    2016-03-15

    Heat-flow sensing is expected to be an important technological component of smart thermal management in the future. Conventionally, the thermoelectric (TE) conversion technique, which is based on the Seebeck effect, has been used to measure a heat flow by converting the flow into electric voltage. However, for ubiquitous heat-flow visualization, thin and flexible sensors with extremely low thermal resistance are highly desired. Recently, another type of TE effect, the longitudinal spin Seebeck effect (LSSE), has aroused great interest because the LSSE potentially offers favourable features for TE applications such as simple thin-film device structures. Here we demonstrate an LSSE-based flexible TE sheet that is especially suitable for a heat-flow sensing application. This TE sheet contained a Ni0.2Zn0.3Fe2.5O4 film which was formed on a flexible plastic sheet using a spray-coating method known as "ferrite plating". The experimental results suggest that the ferrite-plated film, which has a columnar crystal structure aligned perpendicular to the film plane, functions as a unique one-dimensional spin-current conductor suitable for bendable LSSE-based sensors. This newly developed thin TE sheet may be attached to differently shaped heat sources without obstructing an innate heat flux, paving the way to versatile heat-flow measurements and management.

  10. Flexible heat-flow sensing sheets based on the longitudinal spin Seebeck effect using one-dimensional spin-current conducting films

    Science.gov (United States)

    Kirihara, Akihiro; Kondo, Koichi; Ishida, Masahiko; Ihara, Kazuki; Iwasaki, Yuma; Someya, Hiroko; Matsuba, Asuka; Uchida, Ken-Ichi; Saitoh, Eiji; Yamamoto, Naoharu; Kohmoto, Shigeru; Murakami, Tomoo

    2016-03-01

    Heat-flow sensing is expected to be an important technological component of smart thermal management in the future. Conventionally, the thermoelectric (TE) conversion technique, which is based on the Seebeck effect, has been used to measure a heat flow by converting the flow into electric voltage. However, for ubiquitous heat-flow visualization, thin and flexible sensors with extremely low thermal resistance are highly desired. Recently, another type of TE effect, the longitudinal spin Seebeck effect (LSSE), has aroused great interest because the LSSE potentially offers favourable features for TE applications such as simple thin-film device structures. Here we demonstrate an LSSE-based flexible TE sheet that is especially suitable for a heat-flow sensing application. This TE sheet contained a Ni0.2Zn0.3Fe2.5O4 film which was formed on a flexible plastic sheet using a spray-coating method known as “ferrite plating”. The experimental results suggest that the ferrite-plated film, which has a columnar crystal structure aligned perpendicular to the film plane, functions as a unique one-dimensional spin-current conductor suitable for bendable LSSE-based sensors. This newly developed thin TE sheet may be attached to differently shaped heat sources without obstructing an innate heat flux, paving the way to versatile heat-flow measurements and management.

  11. Effects of a dimple potential on the ground-state properties of a quasi-one-dimensional Bose–Einstein condensate with two- and three-body interactions

    Energy Technology Data Exchange (ETDEWEB)

    Karabulut, Elife Ö.

    2015-04-01

    The ground state of a quasi-one-dimensional interacting Bose gas confined by a harmonic plus Gaussian dimple potential is studied within the variational approach and also Gross–Pitaevskii mean-field approximation. The effect of the superimposed dimple trap on the order parameter, the chemical and effective potentials of the system is analyzed for repulsive and attractive two- as well as three-body interactions between the particles. The results obtained from both methods show that the characteristics of the trap such as the width and depth of the dimple affect the corresponding ground state properties of the system in a qualitatively similar way to the repulsive and attractive interatomic interactions, respectively. - Highlights: • We study the effects of a dimple potential on a quasi-1D Bose-Einstein condensate. • We used variational and Gross-Pitaevskii mean-field approaches. • The width of the dimple affects the system similarly to repulsive interaction. • The depth of the dimple affects the system similarly to attractive interaction.

  12. Thermoelectric effects in magnetic nanostructures

    NARCIS (Netherlands)

    Hatami, M.; Bauer, G.E.W.; Zhang, Q.; Kelly, P.J.

    2009-01-01

    We model and evaluate the Peltier and Seebeck effects in magnetic multilayer nanostructures by a finite-element theory of thermoelectric properties. We present analytical expressions for the thermopower and the current-induced temperature changes due to Peltier cooling/heating. The thermopower of a

  13. Thermoelectric effects in magnetic nanostructures

    NARCIS (Netherlands)

    Hatami, M.; Bauer, G.E.W.; Zhang, Q.; Kelly, P.J.

    2009-01-01

    We model and evaluate the Peltier and Seebeck effects in magnetic multilayer nanostructures by a finite-element theory of thermoelectric properties. We present analytical expressions for the thermopower and the current-induced temperature changes due to Peltier cooling/heating. The thermopower of a

  14. One-Dimensional Tunable Josephson Metamaterials

    OpenAIRE

    Butz, Susanne

    2014-01-01

    This thesis presents a novel approach to the experimental realization of tunable, superconducting metamaterials. Therefore, conventional resonant meta-atoms are replaced by meta-atoms that contain Josephson junctions, which renders their resonance frequency tunable by an external magnetic field. This tunability is theoretically and experimentally investigated in one-dimensional magnetic and electric metamaterials. For the magnetic metamaterial, the effective, magnetic permeability is determined.

  15. One-Dimensional Simulation of Clay Drying

    Directory of Open Access Journals (Sweden)

    Siljan Siljan

    2002-04-01

    Full Text Available Drying of clay is simulated by a one-dimensional model. The background of the work is to form a better basis for investigation of the drying process in production of clay-based building materials. A model of one-dimensional heat and mass transfer in porous material is used and modified to simulate drying of clay particles. The convective terms are discretized by first-order upwinding, and the diffusive terms are discretized by central differencing. DASSL was used to solve the set of algebraic and differential equations. The different simulations show the effect of permeability, initial moisture content and different boundary conditions. Both drying of a flat plate and a spherical particle are modelled.

  16. Anomalous Oscillations due to Aharonov-Bohm and Aharonov-Casher Effects of the One-Dimensional Hubbard Ring in the Strong Coupling Limit

    Science.gov (United States)

    Sano, Kazuhiro; Ōno, Yoshiaki

    2016-12-01

    We investigate anomalous oscillations due to the Aharonov-Bohm (AB) and Aharonov-Casher (AC) effects of the one-dimensional Hubbard ring with flux in the strong coupling limit. By using the exact diagonalization method and the Shiba transformation, we examine the energies of the ground-state and a few excited states in the presence of the flux producing the AB or AC effect, where the transformation not only reverses the sign of the interaction U but also exchanges the role between the AB and AC effects in the model Hamiltonian. We systematically classify the AB and AC oscillations by using the number of minima Nmin of the ground-state energy as a function of a normalized phase shift ϕ for 0 ≤ ϕ effects. For example, it is shown that Nmin is given by NL - Ne (NL - N↑ + N↓) for the AB (AC) effect in the very strong attraction, where NL, Ne, N↑, and N↓ are the system size, the total number of electrons, the number of electrons with up-spin, and the number of electrons with down-spin, respectively, under the condition of NL > Ne > N↓ > N↑. In more special cases, such as for a half-filled band and the spin-balanced case (NL = Ne and N↓ = N↑), we find Nmin to be 0 (2) for the AB (AC) effect in the case of very strong repulsion. These results show us the nature of interesting phenomena originating from the interplay between the strong correlation and the quantum interference effect in a mesoscopic ring.

  17. Effects on the Thermo-Mechanical and Crystallinity Properties of Nylon 6,6 Electrospun Fibres Reinforced with One Dimensional (1D and Two Dimensional (2D Carbon

    Directory of Open Access Journals (Sweden)

    Francisco Medellín-Rodríguez

    2013-08-01

    Full Text Available Electrospun one dimensional (1D and two dimensional (2D carbon based polymer nanocomposites are studied in order to determine the effect provided by the two differently structured nanofillers on crystallinity and thermo-mechanical properties of the nanofibres. The nanomaterials studied are pristine carbon nanotubes, oxidised carbon nanotubes, reduced graphene oxide and graphene oxide. Functional groups associated with the order structure of the polymers are analysed by infrared and Raman spectroscopies; the morphology is studied by scanning electron microscopy and the crystallinity properties are investigated by differential scanning calorimetry and X-ray diffraction. Differences in crystallisation behaviour between 1D and 2D carbon based nanofibres are shown by their crystallinity degree and their crystal sizes. The nanocomposite crystal sizes perpendicular to the plane (100 decrease with nanofiller content in all cases. The crystallinity trend and crystal sizes are in accordance with storage modulus response. The results also suggest that functionalisation favours interfacial bonding and dispersion of the nanomaterials within the polymer matrix. As a consequence the number of nucleating sites increases which in turn decreases the crystal size in the nanocomposites. These features explain the improved thermo-mechanical properties in the nanocomposites.

  18. Modelling and engineering of stress based controlled oxidation effects for silicon nanostructure patterning

    Science.gov (United States)

    Han, Xiang-Lei; Larrieu, Guilhem; Krzeminski, Christophe

    2013-12-01

    Silicon nanostructure patterning with tight geometry control is an important challenge at the bottom level. In that context, stress based controlled oxidation appears to be an efficient tool for precise nanofabrication. Here, we investigate the stress-retarded oxidation phenomenon in various silicon nanostructures (nanobeams, nanorings and nanowires) at both the experimental and the theoretical levels. Different silicon nanostructures have been fabricated by a top-down approach. Complex dependence of the stress build-up on the nano-object’s dimension, shape and size has been demonstrated experimentally and physically explained by modelling. For the oxidation of a two-dimensional nanostructure (nanobeam), relative independence to size effects has been observed. On the other hand, radial stress increase with geometry downscaling of a one-dimensional nanostructure (nanowire) has been carefully emphasized. The study of shape engineering by retarded oxidation effects for vertical silicon nanowires is finally discussed.

  19. 大气温室效应的一维辐射传热分析%One Dimensional Radiative Heat Transfer Analysis of Atmosphere Greenhouse Effects

    Institute of Scientific and Technical Information of China (English)

    刘彬; 帅永; 谈和平

    2011-01-01

    大气中温室气体对地面长波热辐射的吸收和再发射导致了温室效应.计算了大气不同高度200~50000 cm-1(0.2~50 μm)光谱吸收系数,采用一维大气介质模型和射线踪迹-节点分析法(RTNAM)的多层模型对大气中二氧化碳及水蒸气不同浓度情况下的大气温度进行了计算.结果表明标准大气CO2浓度增加1倍,对流层的温度上升0.453°C,若水蒸气浓度降低,CO2的温室效应更加明显.%Greenhouse gases absorb the thermal radiation from earth surface and reemit part of energy back. This progress leads to the greenhouse effects. Absorption coefficients at different latitude were calculated form 200 cm-1 to 50000 cm- 1(0.2~50μm). Using a one-dimensional radiative heat transfer model for atmosphere combined with multilayered model by Ray-Tracing/Nodal-Analyzing Method (RTNAM), atmospheric temperature fields were calculated under different CO2 and/or H2O concentration conditions. The results show that temperature in troposphere rise 0.453℃ if doubling of CO2Concentration, and if the concentration of H2O is lower, greenhouse effects of CO2 become more obvious.

  20. A review on one dimensional perovskite nanocrystals for piezoelectric applications

    Directory of Open Access Journals (Sweden)

    Li-Qian Cheng

    2016-03-01

    Full Text Available In recent years, one-dimensional piezoelectric nanomaterials have become a research topic of interest because of their special morphology and excellent piezoelectric properties. This article presents a short review on one dimensional perovskite piezoelectric materials in different systems including Pb(Zr,TiO3, BaTiO3 and (K,NaNbO3 (KNN. We emphasize KNN as a promising lead-free piezoelectric compound with a high Curie temperature and high piezoelectric properties and describe its synthesis and characterization. In particular, details are presented for nanoscale piezoelectricity characterization of a single KNN nanocrystal by piezoresponse force microscopy. Finally, this review describes recent progress in applications based on one dimensional piezoelectric nanostructures with a focus on energy harvesting composite materials.

  1. One-dimensional hypersonic phononic crystals.

    Science.gov (United States)

    Gomopoulos, N; Maschke, D; Koh, C Y; Thomas, E L; Tremel, W; Butt, H-J; Fytas, G

    2010-03-10

    We report experimental observation of a normal incidence phononic band gap in one-dimensional periodic (SiO(2)/poly(methyl methacrylate)) multilayer film at gigahertz frequencies using Brillouin spectroscopy. The band gap to midgap ratio of 0.30 occurs for elastic wave propagation along the periodicity direction, whereas for inplane propagation the system displays an effective medium behavior. The phononic properties are well captured by numerical simulations. The porosity in the silica layers presents a structural scaffold for the introduction of secondary active media for potential coupling between phonons and other excitations, such as photons and electrons.

  2. The one-dimensional compression method for extraction of pore water from unsaturated tuff and effects on pore-water chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Higgins, J.D.; Burger, P.A. [Colorado School of Mines, Golden, CO (United States); Yang, L.C. [Geological Survey, Denver, CO (United States)

    1997-12-31

    Study of the hydrologic system at Yucca Mountain, Nevada, requires extraction of pore-water samples from unsaturated tuff bedrock. Two generations of compression cells have been designed and tested for extracting representative, unaltered pore-water samples from unsaturated tuff cores. The one-dimensional compression cell has a maximum compressive stress rating of 552 MPa. Results from 86 tests show that the minimum degree of saturation for successful extraction of pore water was about 14% for non welded tuff and about 61% for densely welded tuff. The high-pressure, one-dimensional compression cell has a maximum compressive stress rating of 827 MPa. Results from 109 tests show that the minimum degree of saturation for successful extraction of pore water was about 7.5% for non welded tuff and about 34% for densely welded tuff. Geochemical analyses show that, in general, there is a decrease in ion concentration of pore waters as extraction pressures increase. Only small changes in pore-water composition occur during the one-dimensional extraction test.

  3. Parameter variation effects on temperature elevation in a steady-state, one-dimensional thermal model for millimeter wave exposure of one- and three-layer human tissue

    Energy Technology Data Exchange (ETDEWEB)

    Kanezaki, Akio; Shirai, Hiroshi [Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Hirata, Akimasa; Watanabe, Soichi, E-mail: ahirata@nitech.ac.j [National Institute of Information and Communications Technology, 4-2-1 Nukuikitamachi, Koganei-shi, Tokyo 184-8795 (Japan)

    2010-08-21

    The present study describes theoretical parametric analysis of the steady-state temperature elevation in one-dimensional three-layer (skin, fat and muscle) and one-layer (skin only) models due to millimeter-wave exposure. The motivation of this fundamental investigation is that some variability of warmth sensation in the human skin has been reported. An analytical solution for a bioheat equation was derived by using the Laplace transform for the one-dimensional human models. Approximate expressions were obtained to investigate the dependence of temperature elevation on different thermal and tissue thickness parameters. It was shown that the temperature elevation on the body surface decreases monotonically with the blood perfusion rate, heat conductivity and heat transfer from the body to air. Also revealed were the conditions where maximum and minimum surface temperature elevations were observed for different thermal and tissue thickness parameters. The surface temperature elevation in the three-layer model is 1.3-2.8 times greater than that in the one-layer model. The main reason for this difference is attributed to the adiabatic nature of the fat layer. By considering the variation range of thermal and tissue thickness parameters which causes the maximum and minimum temperature elevations, the dominant parameter influencing the surface temperature elevation was found to be the heat transfer coefficient between the body surface and air.

  4. Localized chaos in one-dimensional hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Humm, D.C.; Saltz, D.; Nayfeh, M.H. (Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (USA))

    1990-08-01

    We calculate the response of hydrogen to the presence of both a strong dc electric field (necessary to isolate a nearly one-dimensional motion) and a strong radiation field of higher frequency than the binding energy of the system, a regime that has not previously been examined by theory or experiment. We determine the classical ionization threshold, the quantum-delocalization threshold, and the threshold of {ital n} mixing due to chaotic effects. The analysis indicates that the dc field can have a dramatic effect on the quantum localization of classically chaotic diffusion, changing the delocalization threshold by more than an order of magnitude. Moreover, this system provides a large spectral region in which quantum-mechanical localization inhibits classical chaotic diffusion. This theory is well suited to experimental testing.

  5. One Dimensional Locally Connected S-spaces

    CERN Document Server

    Kunen, Joan E Hart Kenneth

    2007-01-01

    We construct, assuming Jensen's principle diamond, a one-dimensional locally connected hereditarily separable continuum without convergent sequences. The construction is an inverse limit in omega_1 steps, and is patterned after the original Fedorchuk construction of a compact S-space. To make it one-dimensional, each space in the inverse limit is a copy of the Menger sponge.

  6. One-dimensional spinon spin currents

    Science.gov (United States)

    Hirobe, Daichi; Sato, Masahiro; Kawamata, Takayuki; Shiomi, Yuki; Uchida, Ken-Ichi; Iguchi, Ryo; Koike, Yoji; Maekawa, Sadamichi; Saitoh, Eiji

    2017-01-01

    Quantum spin fluctuation in a low-dimensional or frustrated magnet breaks magnetic ordering while keeping spin correlation. Such fluctuation has been a central topic in magnetism because of its relevance to high-Tc superconductivity and topological states. However, utilizing such spin states has been quite difficult. In a one-dimensional spin-1/2 chain, a particle-like excitation called a spinon is known to be responsible for spin fluctuation in a paramagnetic state. Spinons behave as a Tomonaga-Luttinger liquid at low energy, and the spin system is often called a quantum spin chain. Here we show that a quantum spin chain generates and carries spin current, which is attributed to spinon spin current. This is demonstrated by observing an anisotropic negative spin Seebeck effect along the spin chains in Sr2CuO3. The results show that spin current can flow even in an atomic channel owing to long-range spin fluctuation.

  7. One-dimensional reduction of viscous jets

    CERN Document Server

    Pitrou, Cyril

    2015-01-01

    We build a general formalism to describe thin viscous jets as one-dimensional objects with an internal structure. We present in full generality the steps needed to describe the viscous jets around their central line, and we argue that the Taylor expansion of all fields around that line is conveniently expressed in terms of symmetric trace-free tensors living in the two dimensions of the fiber sections. We recover the standard results of axisymmetric jets and we report the first and second corrections to the lowest order description, also allowing for a rotational component around the axis of symmetry. When applied to generally curved fibers, the lowest order description corresponds to a viscous string model whose sections are circular. However, when including the first corrections we find that curved jets generically develop elliptic sections. Several subtle effects imply that the first corrections cannot be described by a rod model, since it amounts to selectively discard some corrections. However, in a fast...

  8. One dimensional models of excitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Duclos, P.; Pedersen, Thomas Garm

    Excitons in carbon nanotubes may be modeled by two oppositely charged particles living on the surface of a cylinder. We derive three one dimensional effective Hamiltonians which become exact as the radius of the cylinder vanishes. Two of them are solvable.......Excitons in carbon nanotubes may be modeled by two oppositely charged particles living on the surface of a cylinder. We derive three one dimensional effective Hamiltonians which become exact as the radius of the cylinder vanishes. Two of them are solvable....

  9. Structure Variation from One-Dimensional Chain to Three-Dimensional Architecture: Effect of Ligand on Construction of Lanthanide Coordination Polymers

    Indian Academy of Sciences (India)

    LEI WANG; WEN-XUAN LI; XIAO-MIN GU; WEN-LI ZHANG; LIANG NI

    2017-02-01

    Four lanthanide coordination polymers were constructed from mixed ligands of phenanthroline derivative and flexible polydentate ligands, [Gd2 (1,3-BDC)3(MOPIP) 2]n•nH2O (1), [Gd(1,4-BDC)1.5(MOPIP)] n• (2), [Yb(1,4-BDC)1.5(MOPIP)] n• (3) and [Sm(1,4-BDC)1.5(MOPIP)] n• (4), (MOPIP = 2-(4-methoxyphenyl)-1Himidazo[ 4,5-f ][1,10]phenanthroline, 1,3-BDC = benzene-1,3- dicarboxylic acid, 1,4-BDC = benzene-1, 4-dicarboxylic acid). The polymers have been synthesized under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction analysis. Compound 1 possesses one-dimensional chain structure,and expands into the three-dimensional supramolecular architecture by π • • • π stacking and hydrogen-bonding interactions. Meanwhile, compounds 2–4 exhibit three-dimensional frameworks with pcu topology (412•63). The structural differences among such compounds show that the steric hindrances of benzene dicarboxylicacid ligands play a key role in the assembly and the structures of the title compounds. Compounds 1 and 2 act as efficient Lewis acid catalysts for the cyanosilylation of benzaldehyde in high yields, due to the strong Lewisacidity

  10. On the anomalies in gold nanoparticles prepared by micelle nanolithography and their impact on one-dimensional material synthesis. Role of substrate, size effects and impurity

    Energy Technology Data Exchange (ETDEWEB)

    Mbenkum, B.N.

    2007-07-23

    The synthesis of one-dimensional (1-D) inorganic semiconductor materials such as nanotubes and silicon (Si) nanowires is usually achieved by catalyst nanoparticlemediated synthetic routes. Despite the well-established nature of this technique, problems such as low temperature synthesis and adequate control of catalyst nanoparticle diameter in order to control 1-D material diameter still prevail. Additionally, the expansion of this technology from crystalline to cheaper substrates such as glass remains demanding. This work employs a previously established selfassembly route to produce controlled spatial distribution of substrate anchored small diameter gold nanoparticles with controlled size. This enabled successful synthesis of Si 1-D structures with controlled diameters less than 20 nm. Low temperature synthesis due to enhanced catalytic activity was achieved via introduction of impurity by treatment of gold nanoparticles in different plasma environments. This enabled Si 1-D structure growth on Si, SiO{sub x}/Si and borosilicate glass substrates at 320 C. Substrate-induced stress affected Si diffusion at the gold nanoparticle determining whether Si nanowires or nanotubes were grown. These results are of technological relevance because low temperature synthesis provides an economical approach and controlled diameter enhances material functionality. Additionally, exploiting substrate-induced stress to influence Si diffusion in nanoparticles provides an alternate route to tuning Si 1-D structure. (orig.)

  11. Strongly anisotropic wetting on one-dimensional nanopatterned surfaces.

    Science.gov (United States)

    Xia, Deying; Brueck, S R J

    2008-09-01

    This communication reports strongly anisotropic wetting behavior on one-dimensional nanopatterned surfaces. Contact angles, degree of anisotropy, and droplet distortion are measured on micro- and nanopatterned surfaces fabricated with interference lithography. Both the degree of anisotropy and the droplet distortion are extremely high as compared with previous reports because of the well-defined nanostructural morphology. The surface is manipulated to tune with the wetting from hydrophobic to hydrophilic while retaining the structural wetting anisotropy with a simple silica nanoparticle overcoat. The wetting mechanisms are discussed. Potential applications in microfluidic devices and evaporation-induced pattern formation are demonstrated.

  12. Exactly solvable one-dimensional inhomogeneous models

    Energy Technology Data Exchange (ETDEWEB)

    Derrida, B.; France, M.M.; Peyriere, J.

    1986-11-01

    The authors present a simple way of constructing one-dimensional inhomogeneous models (random or quasiperiodic) which can be solved exactly. They treat the example of an Ising chain in a varying magnetic field, but their procedure can easily be extended to other one-dimensional inhomogeneous models. For all the models they can construct, the free energy and its derivatives with respect to temperature can be computed exactly at one particular temperature.

  13. Few quantum particles on one dimensional lattices

    Energy Technology Data Exchange (ETDEWEB)

    Valiente Cifuentes, Manuel

    2010-06-18

    There is currently a great interest in the physics of degenerate quantum gases and low-energy few-body scattering due to the recent experimental advances in manipulation of ultracold atoms by light. In particular, almost perfect periodic potentials, called optical lattices, can be generated. The lattice spacing is fixed by the wavelength of the laser field employed and the angle betwen the pair of laser beams; the lattice depth, defining the magnitude of the different band gaps, is tunable within a large interval of values. This flexibility permits the exploration of different regimes, ranging from the ''free-electron'' picture, modified by the effective mass for shallow optical lattices, to the tight-binding regime of a very deep periodic potential. In the latter case, effective single-band theories, widely used in condensed matter physics, can be implemented with unprecedent accuracy. The tunability of the lattice depth is nowadays complemented by the use of magnetic Feshbach resonances which, at very low temperatures, can vary the relevant atom-atom scattering properties at will. Moreover, optical lattices loaded with gases of effectively reduced dimensionality are experimentally accessible. This is especially important for one spatial dimension, since most of the exactly solvable models in many-body quantum mechanics deal with particles on a line; therefore, experiments with one-dimensional gases serve as a testing ground for many old and new theories which were regarded as purely academic not so long ago. The physics of few quantum particles on a one-dimensional lattice is the topic of this thesis. Most of the results are obtained in the tight-binding approximation, which is amenable to exact numerical or analytical treatment. For the two-body problem, theoretical methods for calculating the stationary scattering and bound states are developed. These are used to obtain, in closed form, the two-particle solutions of both the Hubbard and

  14. Cosmic ray ionization and Jesse effect behavior in electrode systems with nanostructures

    CERN Document Server

    Zhan, Changhua

    2012-01-01

    Gaseous electronic characteristics due to cosmic ray ionization in the electrode systems with ZnO and carbon nanostructures have been examined in atmospheric Ar/N2 and O2/N2 mixtures. The electric conductivity at the quasi linear stage is measured at the level of 10-11~10-10 S/m, 4~5 orders of magnitudes higher than that of the samples without nanostructures, which is construed by the 108~1010 times increment of the cosmic ray ionization frequency. The results are consistent with the hypothesis that the role of one-dimensional nanostructures in this gaseous electronic phenomenon is based on the intensive field gradient effect, rather than the field enhancement effect.

  15. Stationary one-dimensional dispersive shock waves

    CERN Document Server

    Kartashov, Yaroslav V

    2011-01-01

    We address shock waves generated upon the interaction of tilted plane waves with negative refractive index defect in defocusing media with linear gain and two-photon absorption. We found that in contrast to conservative media where one-dimensional dispersive shock waves usually exist only as nonstationary objects expanding away from defect or generating beam, the competition between gain and two-photon absorption in dissipative medium results in the formation of localized stationary dispersive shock waves, whose transverse extent may considerably exceed that of the refractive index defect. One-dimensional dispersive shock waves are stable if the defect strength does not exceed certain critical value.

  16. Synthesis and application of one-dimensional nanomaterials

    Science.gov (United States)

    Zhang, Daihua

    My research has been focused on the synthesis, characterization and application of three types of one-dimensional (1D) nanostructures, including metal oxide nanowires, transition metal oxide core-shell nanocables, and carbon nanotubes. They represent a new class of materials that have attracted steadily growing interest due to their peculiar properties and unique applications complementary to bulk materials. This dissertation will summarize my studies on these three 1D nanomaterials, as well as propose future research work that may lead to further development of this field. Following a brief introduction to 1D nanomaterials in Chapter 1, Chapter 2 will focus on the first material - metal oxide nanowires. The discussion starts from the synthesis approach and material characterization of metal oxide nanowires, and then shifts to the electron transport properties and potential applications. A series of functional devices based on In2O 3 and SnO2 nanowires will be demonstrated and evaluated, which range from field effect transistors (FETs), nonvolatile memories, to photo-detecting devices and chemical sensors. Chapter 3 will discuss the fabrication of transition metal oxide (TMO) core-shell nanocables and their electron transport properties as a function of temperature and external magnetic field. The discussion will primarily focus on one of the TMO materials---magnetite (Fe3O 4) core-shell nanowires and nanotubes. Chapter 4 focuses on the application of carbon nanotubes (CNTs) in macroelectronics and explores the feasibility of using CNT films as transparent electrodes for organic light emitting diodes (OLEDs). Chapter 5, in the end, summarizes the above discussions and proposes future research directions in 1D nanomaterials.

  17. One-dimensional oscillator in a box

    Energy Technology Data Exchange (ETDEWEB)

    Amore, Paolo [Facultad de Ciencias, Universidad de Colima, Bernal DIaz del Castillo 340, Colima, Colima (Mexico); Fernandez, Francisco M [INIFTA (UNLP, CCT La Plata-CONICET), Division Quimica Teorica, Blvd 113 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)], E-mail: paolo@ucol.mx, E-mail: fernande@quimica.unlp.edu.ar

    2010-01-15

    We discuss a quantum-mechanical model of two particles that interact by means of a harmonic potential and are confined to a one-dimensional box with impenetrable walls. We apply perturbation theory to the cases of different and equal masses and analyse the symmetry of the states in the latter case. We compare the approximate perturbation results with accurate numerical ones.

  18. QUASI-ONE DIMENSIONAL CLASSICAL FLUIDS

    Directory of Open Access Journals (Sweden)

    J.K.Percus

    2003-01-01

    Full Text Available We study the equilibrium statistical mechanics of simple fluids in narrow pores. A systematic expansion is made about a one-dimensional limit of this system. It starts with a density functional, constructed from projected densities, which depends upon projected one and two-body potentials. The nature of higher order corrections is discussed.

  19. Highly conducting one-dimensional solids

    CERN Document Server

    Evrard, Roger; Doren, Victor

    1979-01-01

    Although the problem of a metal in one dimension has long been known to solid-state physicists, it was not until the synthesis of real one-dimensional or quasi-one-dimensional systems that this subject began to attract considerable attention. This has been due in part to the search for high­ temperature superconductivity and the possibility of reaching this goal with quasi-one-dimensional substances. A period of intense activity began in 1973 with the report of a measurement of an apparently divergent conduc­ tivity peak in TfF-TCNQ. Since then a great deal has been learned about quasi-one-dimensional conductors. The emphasis now has shifted from trying to find materials of very high conductivity to the many interesting problems of physics and chemistry involved. But many questions remain open and are still under active investigation. This book gives a review of the experimental as well as theoretical progress made in this field over the last years. All the chapters have been written by scientists who have ...

  20. One-dimensional models of excitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Duclos, Pierre; Pedersen, Thomas Garm

    2004-01-01

    Excitons in carbon nanotubes may be modeled by two oppositely charged particles living on the surface of a cylinder. We derive three one-dimensional effective Hamiltonians which become exact as the radius of the cylinder vanishes. Two of them are solvable.......Excitons in carbon nanotubes may be modeled by two oppositely charged particles living on the surface of a cylinder. We derive three one-dimensional effective Hamiltonians which become exact as the radius of the cylinder vanishes. Two of them are solvable....

  1. One-dimensional nano-interconnection formation.

    Science.gov (United States)

    Ji, Jianlong; Zhou, Zhaoying; Yang, Xing; Zhang, Wendong; Sang, Shengbo; Li, Pengwei

    2013-09-23

    Interconnection of one-dimensional nanomaterials such as nanowires and carbon nanotubes with other parts or components is crucial for nanodevices to realize electrical contacts and mechanical fixings. Interconnection has been being gradually paid great attention since it is as significant as nanomaterials properties, and determines nanodevices performance in some cases. This paper provides an overview of recent progress on techniques that are commonly used for one-dimensional interconnection formation. In this review, these techniques could be categorized into two different types: two-step and one-step methods according to their established process. The two-step method is constituted by assembly and pinning processes, while the one-step method is a direct formation process of nano-interconnections. In both methods, the electrodeposition approach is illustrated in detail, and its potential mechanism is emphasized.

  2. Nanocoatings size effect in nanostructured films

    CERN Document Server

    Aliofkhazraei, Mahmood

    2014-01-01

    Size effect in structures has been taken into consideration over the last years. In comparison with coatings with micrometer-ranged thickness, nanostructured coatings usually enjoy better and appropriate properties, such as strength and resistance. These coatings enjoy unique magnetic properties and are used with the aim of producing surfaces resistant against erosion, lubricant system, cutting tools, manufacturing hardened sporadic alloys, being resistant against oxidation and corrosion. This book reviews researches on fabrication and classification of nanostructured coatings with focus on size effect in nanometric scale. Size effect on electrochemical, mechanical and physical properties of nanocoatings are presented.

  3. Vectorlike representation of one-dimensional scattering

    CERN Document Server

    Sánchez-Soto, L L; Barriuso, A G; Monzon, J J

    2004-01-01

    We present a self-contained discussion of the use of the transfer-matrix formalism to study one-dimensional scattering. We elaborate on the geometrical interpretation of this transfer matrix as a conformal mapping on the unit disk. By generalizing to the unit disk the idea of turns, introduced by Hamilton to represent rotations on the sphere, we develop a method to represent transfer matrices by hyperbolic turns, which can be composed by a simple parallelogramlike rule.

  4. Momentum Dynamics of One Dimensional Quantum Walks

    CERN Document Server

    Fuss, I; Sherman, P J; Naguleswaran, S; Fuss, Ian; White, langord B.; Sherman, Peter J.; Naguleswaran, Sanjeev

    2006-01-01

    We derive the momentum space dynamic equations and state functions for one dimensional quantum walks by using linear systems and Lie group theory. The momentum space provides an analytic capability similar to that contributed by the z transform in discrete systems theory. The state functions at each time step are expressed as a simple sum of three Chebyshev polynomials. The functions provide an analytic expression for the development of the walks with time.

  5. Effect of Lorentz local field correction on propagation of ultrashort laser pulse in one-dimensional para-nitroaniline (PNA)molecules

    Institute of Scientific and Technical Information of China (English)

    Zhou Yong; Miao Quan; Wang Chuan-Kui

    2011-01-01

    This paper investigates the effect of Lorentz local field correction(LFC)on the propagation of ultrashort laser pulses in a para-nitroaniline molecular medium under resonant and nonresonant conditions by solving numerically the full-wave Maxwell-Bloch equations beyond slowly-varying envelope approximation and rotating-wave approximation.The effect of the LFC is considerably obvious when pulses with large areas propagate in the dense molecular medium.In the case of resonance, the group velocity of the sub-pulses split from the incident pulse along propagation is severely decreased by the LFC, especially for the latest sub-pulse. However, in the case of nonresonance, the influence of the LFC on the temporal evolution of the pulse is less obvious and lacks homogeneity with an increase in incident pulse area, propagation distance and molecular density.

  6. Characterization of acoustic black hole effect using a one-dimensional fully-coupled and wavelet-decomposed semi-analytical model

    Science.gov (United States)

    Tang, Liling; Cheng, Li; Ji, Hongli; Qiu, Jinhao

    2016-07-01

    Acoustics Black Hole (ABH) effect shows promising features for potential vibration control and energy harvesting applications. The phenomenon occurs in a structure with diminishing thickness which gradually reduces the phase velocity of flexural waves. The coupling between the tailored ABH structure and the damping layer used to compensate for the adverse effect of the unavoidable truncation is critical and has not been well apprehended by the existing models. This paper presents a semi-analytical model to analyze an Euler-Bernoulli beam with embedded ABH feature and its full coupling with the damping layers coated over its surface. By decomposing the transverse displacement field of the beam over the basis of a set of Mexican hat wavelets, the extremalization of the Hamiltonian via Lagrange's equation yields a set of linear equations, which can be solved for structural responses. Highly consistent with the FEM and experimental results, numerical simulations demonstrate that the proposed wavelet-based model is particularly suitable to characterize the ABH-induced drastic wavelength fluctuation phenomenon. The ABH feature as well as the effect of the wedge truncation and that of the damping layers on the vibration response of the beam is analyzed. It is shown that the mass of the damping layers needs particular attention when their thickness is comparable to that of the ABH wedge around the tip area. Due to its modular and energy-based feature, the proposed framework offers a general platform allowing embodiment of other control or energy harvesting elements into the model to guide ABH structural design for various applications.

  7. Magnetic field effect on the laser-driven density of states for electrons in a cylindrical quantum wire: transition from one-dimensional to zero-dimensional behavior

    Energy Technology Data Exchange (ETDEWEB)

    Lima, C P; Lima, F M S; Fonseca, A L A; Nunes, O A C, E-mail: fabio@fis.unb.br [Institute of Physics, University of Brasilia and International Center of Condensed Matter Physics, PO Box 04455, 70919-970, Brasilia-DF (Brazil)

    2011-07-15

    The influence of a uniform magnetic field on the density of states (DoS) for carriers confined in a cylindrical semiconductor quantum wire irradiated by a monochromatic, linearly polarized, intense laser field is computed here non-perturbatively, following the Green's function scheme introduced by some of the authors in a recent work (Lima et al 2009 Solid State Commun. 149 678). Besides the known changes in the DoS provoked by an intense terahertz laser field-namely, a significant reduction and the appearance of Franz-Keldysh-like oscillations-our model reveals that the inclusion of a longitudinal magnetic field induces additional blueshifts on the energy levels of the allowed states. Our results show that the increase of the blueshifts with the magnitude of the magnetic field depends only on the azimuthal quantum number m (m=0, 1, 2, ...), being more pronounced for states with higher values of m, which leads to some energy crossovers. For all states, we have obtained, even in the absence of a magnetic field, a localization effect that leads to a transition in the DoS from the usual profile of quasi-1D systems to a peaked profile typical of quasi-0D systems, as e.g. those found for electrons confined in a quantum dot.

  8. Approximate Analytical Solution for One-Dimensional Solidification Problem of a Finite Superheating Phase Change Material Including the Effects of Wall and Thermal Contact Resistances

    Directory of Open Access Journals (Sweden)

    Hamid El Qarnia

    2012-01-01

    Full Text Available This work reports an analytical solution for the solidification of a superheating phase change material (PCM contained in a rectangular enclosure with a finite height. The analytical solution has been obtained by solving nondimensional energy equations by using the perturbation method for a small perturbation parameter: the Stefan number, ε. This analytical solution, which takes into account the effects of the superheating of PCM, finite height of the enclosure, thickness of the wall, and wall-solid shell interfacial thermal resistances, was expressed in terms of nondimensional temperature distributions of the bottom wall of the enclosure and both PCM phases, and the dimensionless solid-liquid interface position and its dimensionless speed. The developed solution was firstly compared with that existing in the literature for the case of nonsuperheating PCM. The predicted results agreed well with those published in the literature. Next, a parametric study was carried out in order to study the impacts of the dimensionless control parameters on the dimensionless temperature distributions of the wall, the solid shell, and liquid phase of the PCM, as well as the solid-liquid interface position and its dimensionless speed.

  9. Efficient electrostatic self-assembly of one-dimensional CdS-Au nanocomposites with enhanced photoactivity, not the surface plasmon resonance effect

    Science.gov (United States)

    Liu, Siqi; Xu, Yi-Jun

    2013-09-01

    A series of CdS nanowire-Au nanocomposites (CdS NW-Au NCs) with different weight addition ratios of Au nanoparticles (NPs) are successfully synthesized by using a simple and efficient electrostatic self-assembly method at room temperature for utilizing the natural surface charge properties of the CdS NWs and Au NPs. These natural surface charge properties are dependent on the synthesis approaches. The probe reactions for photocatalytic selective reduction of nitroaromatic compounds in the aqueous phase under visible light irradiation are utilized to evaluate the photoactivity of this series of as-prepared CdS NW-Au NCs. The CdS NW-Au NCs exhibit significantly enhanced photoactivity as compared to the CdS nanowires (CdS NWs). The addition of Au NPs into the CdS NW domain enables efficient enhancement of the lifetime and transfer of photogenerated charge carriers from CdS NWs under visible light irradiation. However, the addition of excess amounts of Au NPs not only influences the penetration of light but the Au NPs also become the recombination centers, and result in decreased photoactivity. The optimal proportion of the Au NPs is proved to be 1 wt%, which indicates the synergistic effect between the CdS NWs and Au NPs. In addition, the surface plasmon resonance (SPR) effect of Au NPs is proved to not play an efficient role in the reaction and the possible photocatalytic reaction mechanism is proposed. It is hoped that this work could aid in the fabrication of 1-D semiconductor-metal nanocomposites by using such a simple and efficient electrostatic self-assembly strategy. In addition, it is also expected to enrich and supplement their application as visible light photocatalysts toward selective organic transformations through our investigation.A series of CdS nanowire-Au nanocomposites (CdS NW-Au NCs) with different weight addition ratios of Au nanoparticles (NPs) are successfully synthesized by using a simple and efficient electrostatic self-assembly method at room

  10. Chemical Gated Field Effect Transistor by Hybrid Integration of One-Dimensional Silicon Nanowire and Two-Dimensional Tin Oxide Thin Film for Low Power Gas Sensor.

    Science.gov (United States)

    Han, Jin-Woo; Rim, Taiuk; Baek, Chang-Ki; Meyyappan, M

    2015-09-30

    Gas sensors based on metal-oxide-semiconductor transistor with the polysilicon gate replaced by a gas sensitive thin film have been around for over 50 years. These are not suitable for the emerging mobile and wearable sensor platforms due to operating voltages and powers far exceeding the supply capability of batteries. Here we present a novel approach to decouple the chemically sensitive region from the conducting channel for reducing the drive voltage and increasing reliability. This chemically gated field effect transistor uses silicon nanowire for the current conduction channel with a tin oxide film on top of the nanowire serving as the gas sensitive medium. The potential change induced by the molecular adsorption and desorption allows the electrically floating tin oxide film to gate the silicon channel. As the device is designed to be normally off, the power is consumed only during the gas sensing event. This feature is attractive for the battery operated sensor and wearable electronics. In addition, the decoupling of the chemical reaction and the current conduction regions allows the gas sensitive material to be free from electrical stress, thus increasing reliability. The device shows excellent gas sensitivity to the tested analytes relative to conventional metal oxide transistors and resistive sensors.

  11. Self-consistent field theory of tethered polymers: One dimensional, three dimensional, strong stretching theories and the effects of excluded-volume-only interactions

    Energy Technology Data Exchange (ETDEWEB)

    Suo, Tongchuan, E-mail: suotc@physics.umanitoba.ca; Whitmore, Mark D., E-mail: mark-whitmore@umanitoba.ca [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

    2014-11-28

    We examine end-tethered polymers in good solvents, using one- and three-dimensional self-consistent field theory, and strong stretching theories. We also discuss different tethering scenarios, namely, mobile tethers, fixed but random ones, and fixed but ordered ones, and the effects and important limitations of including only binary interactions (excluded volume terms). We find that there is a “mushroom” regime in which the layer thickness is independent of the tethering density, σ, for systems with ordered tethers, but we argue that there is no such plateau for mobile or disordered anchors, nor is there one in the 1D theory. In the other limit of brushes, all approaches predict that the layer thickness scales linearly with N. However, the σ{sup 1/3} scaling is a result of keeping only excluded volume interactions: when the full potential is included, the dependence is faster and more complicated than σ{sup 1/3}. In fact, there does not appear to be any regime in which the layer thickness scales in the combination Nσ{sup 1/3}. We also compare the results for two different solvents with each other, and with earlier Θ solvent results.

  12. Quasi-one-dimensional scattering in a discrete model

    DEFF Research Database (Denmark)

    Valiente, Manuel; Mølmer, Klaus

    2011-01-01

    that more than one confinement-induced resonances appear due to the nonseparability of the center-of-mass and relative coordinates on the lattice. This is done by solving its corresponding Lippmann-Schwinger-like equation. We characterize the effective one-dimensional interaction and compare it with a model...

  13. Three isostructural one-dimensional Ln(III) chains with distorted cubane motifs showing dual fluorescence and slow magnetic relaxation/magnetocaloric effect.

    Science.gov (United States)

    Li, Yan; Yu, Jia-Wen; Liu, Zhong-Yi; Yang, En-Cui; Zhao, Xiao-Jun

    2015-01-05

    Three new homometallic lanthanide complexes with mixed carboxylate-modified rigid ligands, [Ln(μ3-OH)(na)(pyzc)]n (na(-) = 1-naphtholate, pyzc(-) = 2-pyrazinecarboxylate, Ln = Dy (1), Yb (2), and Gd (3)), were solvothermally synthesized, and their structures and magnetic as well as photophysical properties were completely investigated. Complexes 1-3 are crystallographically isostructural, exhibiting linear chains with four bidentate bridging μ-COO(-) moieties encapsulated cubic {Ln4(μ3-OH)4}(8+) clusters repeatedly extended by 4-fold chelating-bridging-pyzc(-) connectors. Magnetically, the former two complexes with highly anisotropic Dy(III) and weak anisotropic Yb(III) ions in the distorted NO7 triangular dodecahedron coordination environment display field-induced slow relaxation of magnetization. Fitting the dynamic magnetic data to the Arrhenius law gives energy barrier ΔE/kB = 39.6 K and pre-exponential factor τo = 1.52 × 10(-8) s for 1 and ΔE/kB = 14.1 K and τo = 2.13 × 10(-7) s for 2. By contrast, complex 3 with isotropic Gd(III) ion and weak intracluster antiferromagnetic coupling shows a significant cryogenic magnetocaloric effect, with a maximum -ΔSm value of 30.0 J kg(-1) K(-1) at 2.5 K and 70 kOe. Additionally, the chromophoric na(-) and pyzc(-) ligands can serve as antenna groups, selectively sensitizing the Dy(III)- and Yb(III)-based luminescence of 1 and 2 in the UV-visible region by an intramolecular energy transfer process. Thus, complexes 1-3, incorporating field-induced slow magnetic magnetization and interesting luminescence together, can be used as composite magneto-optical materials. More importantly, these interesting results further demonstrate that the mixed-ligand system with rigid carboxylate-functionalized chromophores can be excellent candidates for the preparations of new bifunctional magneto-optical materials.

  14. Research on the Effects of Additional Delta Barrier to One Dimensional Semi-infinite Deep Potential Well%附加δ势垒对一维半无限深势阱影响的研究

    Institute of Scientific and Technical Information of China (English)

    唐义甲; 韩修林

    2015-01-01

    By adding the delta barrier of one dimensional semi-infinite deep potential well,and solving the schrodinger equa-tion, the related formula of particle movement of wave function and energy level are obtained. Through analysis we found that the delta barrier to add and its change on the energy level of the position and strength are affected. Contrast does not contain the delta barrier in one dimensional semi-infinite deep trap energy level. In addition, we explore the delta barrier to add to the impact of the original energy level, and use the Mathematica graphic visual indication to this effect.%通过对添加δ势垒的一维半无限深势阱的薛定谔方程进行求解,得到了粒子运动的波函数和能级的相关公式,分析发现,δ势垒的添加以及它的强度与位置的变化对能级都有影响。对比不含δ势垒的一维半无限深势阱的能级,探究δ势垒的添加对原能级产生的影响,并利用Mathematica作图来直观显示这一影响。

  15. Screening effect on nanostructure of charged gel

    DEFF Research Database (Denmark)

    Sugiyama, M; Annaka, M; Hino, M

    2004-01-01

    Charge screening effects on nanostructures of N-isopropylacrylamide-sodium acrylate (NIPA-SA) and -acrylic acid (NIPA-AAc) gels are investigated with small-angle neutron scattering. The NIPA-SA and NIPA-AAc gels with low water content exhibit microphase separations with different dimensions....... The dehydrated NIPA-SA gel also makes the microphase separation but the dehydrated NIPA-AAc gel does not. These results indicate that ionic circumstance around charged bases strongly affects the nanostructures both of the dehydrated gel and the gel with low water content. (C) 2004 Elsevier B. V. All rights...

  16. One-Dimensional TiO2-B Crystals Synthesised by Hydrothermal Process and Their Antibacterial Behaviour on Escherichia coli

    Directory of Open Access Journals (Sweden)

    Sergio León-Ríos

    2016-01-01

    Full Text Available We have successfully synthesised one-dimensional single crystals of monoclinic phase titanium dioxide nanostructures (TiO2-B, prepared by a hydrothermal process. Morphological characterization was carried out by atomic force and scanning and transmission electron microscopy techniques. In order to study the crystalline structure, samples were calcined at 500°C in an air-filled chamber. X-ray diffraction results indicated that as-prepared samples presented diffraction patterns of hydrate hydrogen titanate and those calcined at 500°C exhibited the TiO2-B and anatase phases, confirmed by Raman spectroscopy. Scanning electron microscopy results showed that the one-dimensional nanostructures had high contrast and uniform widths for those synthesised and calcined, indicating the formation of a phase of monocrystals. Besides, a proof of the antibacterial effect was carried out of the monoclinic phase of TiO2-B on Escherichia coli pure cultures, where the viability of the bacterium decreases in presence of TiO2-B nanostructures plus UV illumination. Monocrystals did not change after photocatalytic tests, suggesting a possible application as long-term antibacterial protection.

  17. One-Dimensional Anisotropic Band Gap Structure

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The band gap structure of one-dimensional anisotropic photonic crystal has been studied by means of the transfer matrix formalism. From the analytic expressions and numeric calculations we see some general characteristics of the band gap structure of anisotropic photonic crystals, each band separates into two branches and the two branches react to polarization sensitively. In the practical case of oblique incidence, gaps move towards high frequency when the angle of incidence increases. Under some special conditions, the two branches become degenerate again.

  18. Distibines, New One-Dimensional Materials.

    Science.gov (United States)

    2014-09-26

    Diarsines, Distibines * and Dibismuthines," XI International Conference on Organometallic * Chemistry , Pine Mountain, Georgia, October 1983. (vi...D-R158 534 DISTIINES NEW ONE-DIMENSIONAL MTERILS(U) ICHIGAN i/UNJY ANN ARBOR DEPT OF CHEMISTRY A J ASHE 17 NAY 85 RFOSR-TR-85-9592 RFOSR-81-909 N...ADDRESS (Ci, Stett, and ZIP Code) Department of Chemistry , University Building 410, Bolling AFS, D.C. of Michigan, Ann Arbor, MI 48109 20332-6448 Sa

  19. Collapsing of chaos in one dimensional maps

    Science.gov (United States)

    Yuan, Guocheng; Yorke, James A.

    2000-02-01

    In their numerical investigation of the family of one dimensional maps f l(x)=1-2∣x∣ l, where l>2 , Diamond et al. [P. Diamond et al., Physica D 86 (1999) 559-571] have observed the surprising numerical phenomenon that a large fraction of initial conditions chosen at random eventually wind up at -1, a repelling fixed point. This is a numerical artifact because the continuous maps are chaotic and almost every (true) trajectory can be shown to be dense in [-1,1]. The goal of this paper is to extend and resolve this obvious contradiction. We model the numerical simulation with a randomly selected map. While they used 27 bit precision in computing f l, we prove for our model that this numerical artifact persists for an arbitrary high numerical prevision. The fraction of initial points eventually winding up at -1 remains bounded away from 0 for every numerical precision.

  20. Superfluid helium-4 in one dimensional channel

    Science.gov (United States)

    Kim, Duk Y.; Banavar, Samhita; Chan, Moses H. W.; Hayes, John; Sazio, Pier

    2013-03-01

    Superfluidity, as superconductivity, cannot exist in a strict one-dimensional system. However, the experiments employing porous media showed that superfluid helium can flow through the pores of nanometer size. Here we report a study of the flow of liquid helium through a single hollow glass fiber of 4 cm in length with an open id of 150 nm between 1.6 and 2.3 K. We found the superfluid transition temperature was suppressed in the hollow cylinder and that there is no flow above the transition. Critical velocity at temperature below the transition temperature was determined. Our results bear some similarity to that found by Savard et. al. studying the flow of helium through a nanohole in a silicon nitrite membrane. Experimental study at Penn State is supported by NSF Grants No. DMR 1103159.

  1. One-dimensional Vlasov-Maxwell equilibria

    Science.gov (United States)

    Greene, John M.

    1993-06-01

    The purpose of this paper is to show that the Vlasov equilibrium of a plasma of charged particles in an electromagnetic field is closely related to a fluid equilibrium, where only a few moments of the velocity distribution of the plasma are considered. In this fluid equilibrium the electric field should be calculated from Ohm's law, rather than the Poisson equation. In practice, only one-dimensional equilibria are treated, because the symmetry makes this case tractable. The emphasis here is on gaining a better understanding of the subject, but an alternate way of doing the calculations is suggested. It is shown that particle distributions can be found that are consistent with any reasonable electromagnetic field profile.

  2. Thermal Growth and Nanomagnetism of the Quasi-one Dimensional Iron Oxide

    Institute of Scientific and Technical Information of China (English)

    Minglong Zhong; Zhongwu Liu; Xichun Zhong; Hongya Yu; Dechang Zeng

    2011-01-01

    Quasi-one dimensional iron oxide nanowires with flat needle shape were synthesized on the iron powders by a rather simple catalyst-free thermal oxidation process in ambient atmosphere. The characterization by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman and high-resolution transmission electron microscopy (HRTEM) revealed that these nanos- tructures are single crystalline α-Fe2O3. The various dimensions with 40-170 nm in width and 1-8 μm in length were obtained by tuning the growth temperature from 280 to 480℃. A surface diffusion mechanism was proposed to account for the growth of quasi-one dimensional nanostructure. The typical α-Fe203 nanowires synthesized at 430℃ had a reduced Morin temperature TM of 131 K in comparison with their bulk counterpart. The coercivitis Hc of these nanowires are 321 and 65 Oe at 5 and 300 K, respectively. The temperature of synthesis also has important effects on the magnetic properties of these nanowires.

  3. Nonequilibrium statistical mechanics in one-dimensional bose gases

    Science.gov (United States)

    Baldovin, F.; Cappellaro, A.; Orlandini, E.; Salasnich, L.

    2016-06-01

    We study cold dilute gases made of bosonic atoms, showing that in the mean-field one-dimensional regime they support stable out-of-equilibrium states. Starting from the 3D Boltzmann-Vlasov equation with contact interaction, we derive an effective 1D Landau-Vlasov equation under the condition of a strong transverse harmonic confinement. We investigate the existence of out-of-equilibrium states, obtaining stability criteria similar to those of classical plasmas.

  4. One-Dimensional Tunable Josephson Metamaterials - Eindimensionale stimmbare Josephson Metamaterialien

    OpenAIRE

    Butz, Susanne

    2014-01-01

    This thesis presents a novel approach to the experimental realization of tunable, superconducting metamaterials. Therefore, conventional resonant meta-atoms are replaced by meta-atoms that contain Josephson junctions, which renders their resonance frequency tunable by an external magnetic field. This tunability is theoretically and experimentally investigated in one-dimensional magnetic and electric metamaterials. For the magnetic metamaterial, the effective, magnetic permeability is determined.

  5. One-dimensional photonic band gaps in optical lattices

    CERN Document Server

    Samoylova, Marina; Holynski, Michael; Courteille, Philippe Wilhelm; Bachelard, Romain

    2013-01-01

    The phenomenon of photonic band gaps in one-dimensional optical lattices is reviewed using a microscopic approach. Formally equivalent to the transfer matrix approach in the thermodynamic limit, a microscopic model is required to study finite-size effects, such as deviations from the Bragg condition. Microscopic models describing both scalar and vectorial light are proposed, as well as for two- and three-level atoms. Several analytical results are compared to experimental data, showing a good agreement.

  6. Direct Current Hopping Conductivity in One-Dimensional Nanometre Systems

    Institute of Scientific and Technical Information of China (English)

    宋祎璞; 徐慧; 罗峰

    2003-01-01

    A one-dimensional random nanocrystalline chain model is established. A dc electron-phonon-field conductance model of electron tunnelling transfer is set up, and a new dc conductance formula in one-dimensional nanometre systems is derived. By calculating the dc conductivity, the relationship among the electric field, temperature and conductivity is analysed, and the effect of the crystalline grain size and the distortion of interfacial atoms on the dc conductance is discussed. The result shows that the nanometre system appears the characteristic of negative differential dependence of resistance and temperature at low temperature. The dc conductivity of nanometre systems varies with the change of electric field and trends to rise as the crystalline grain size increases and to decrease as the distorted degree of interfacial atoms increases.

  7. Fate of classical solitons in one-dimensional quantum systems.

    Energy Technology Data Exchange (ETDEWEB)

    Pustilnik, M.; Matveev, K. A.

    2015-11-23

    We study one-dimensional quantum systems near the classical limit described by the Korteweg-de Vries (KdV) equation. The excitations near this limit are the well-known solitons and phonons. The classical description breaks down at long wavelengths, where quantum effects become dominant. Focusing on the spectra of the elementary excitations, we describe analytically the entire classical-to-quantum crossover. We show that the ultimate quantum fate of the classical KdV excitations is to become fermionic quasiparticles and quasiholes. We discuss in detail two exactly solvable models exhibiting such crossover, the Lieb-Liniger model of bosons with weak contact repulsion and the quantum Toda model, and argue that the results obtained for these models are universally applicable to all quantum one-dimensional systems with a well-defined classical limit described by the KdV equation.

  8. Quasi-one-dimensional scattering in a discrete model

    Energy Technology Data Exchange (ETDEWEB)

    Valiente, Manuel; Moelmer, Klaus [Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)

    2011-11-15

    We study quasi-one-dimensional scattering of one and two particles with short-range interactions on a discrete lattice model in two dimensions. One of the directions is tightly confined by an arbitrary trapping potential. We obtain the collisional properties of these systems both at finite and zero Bloch quasimomenta, considering as well finite sizes and transversal traps that support a continuum of states. This is made straightforward by using the exact ansatz for the quasi-one-dimensional states from the beginning. In the more interesting case of genuine two-particle scattering, we find that more than one confinement-induced resonances appear due to the nonseparability of the center-of-mass and relative coordinates on the lattice. This is done by solving its corresponding Lippmann-Schwinger-like equation. We characterize the effective one-dimensional interaction and compare it with a model that includes only the effect of the dominant, broadest resonance, which amounts to a single-pole approximation for the interaction coupling constant.

  9. One dimensional Si/Sn - based nanowires and nanotubes for lithium-ion energy storage materials

    KAUST Repository

    Choi, Nam-Soon

    2011-01-01

    There has been tremendous interest in using nanomaterials for advanced Li-ion battery electrodes, particularly to increase the energy density by using high specific capacity materials. Recently, it was demonstrated that one dimensional (1D) Si/Sn nanowires (NWs) and nanotubes (NTs) have great potential to achieve high energy density as well as long cycle life for the next generation of advanced energy storage applications. In this feature article, we review recent progress on Si-based NWs and NTs as high capacity anode materials. Fundamental understanding and future challenges on one dimensional nanostructured anode are also discussed. © 2010 The Royal Society of Chemistry.

  10. Analysis of necking based on a one-dimensional model

    Science.gov (United States)

    Audoly, Basile; Hutchinson, John W.

    2016-12-01

    Dimensional reduction is applied to derive a one-dimensional energy functional governing tensile necking localization in a family of initially uniform prismatic solids, including as particular cases rectilinear blocks in plane strain and cylindrical bars undergoing axisymmetric deformations. The energy functional depends on both the axial stretch and its gradient. The coefficient of the gradient term is derived in an exact and general form. The one-dimensional model is used to analyze necking localization for nonlinear elastic materials that experience a maximum load under tensile loading, and for a class of nonlinear materials that mimic elastic-plastic materials by displaying a linear incremental response when stretch switches from increasing to decreasing. Bifurcation predictions for the onset of necking from the simplified theory compared with exact results suggest the approach is highly accurate at least when the departures from uniformity are not too large. Post-bifurcation behavior is analyzed to the point where the neck is fully developed and localized to a region on the order of the thickness of the block or bar. Applications to the nonlinear elastic and elastic-plastic materials reveal the highly unstable nature of necking for the former and the stable behavior for the latter, except for geometries where the length of the block or bar is very large compared to its thickness. A formula for the effective stress reduction at the center of a neck is established based on the one-dimensional model, which is similar to that suggested by Bridgman (1952).

  11. One-dimensional nanomaterials: Synthesis and applications

    Science.gov (United States)

    Lei, Bo

    My research mainly covers three types of one-dimensional (1D) nanomaterials: metal oxide nanowires, transition metal oxide core-shell nanowires and single-walled carbon nanotubes. This new class of nanomaterials has generated significant impact in multiple fields including electronics, medicine, computing and energy. Their peculiar, fascinating properties are promising for unique applications on electronics, spintronics, optical and chemical/biological sensing. This dissertation will summarize my research work on these three 1D nanomaterials and propose some ideas that may lead to further development. Chapter 1 will give a brief introduction of nanotechnology journey and 1D nanomaterials. Chapter 2 and 3 will discuss indium oxide nanowires, as the representative of metal oxide nanwires. More specifically, chapter 2 is focused on the synthesis, material characterization, transport studies and doping control of indium oxide nanowires; Chapter 3 will give a comprehensive review of our systematic studies on molecular memory applications based on molecule/indium oxide nanowire heterostructures. Chapter 4 will introduce another 1D nanomaterial-transition metal oxide (TMO) core-shell nanowires. The discuss will focus on the synthesis of TMO nanowires, material analysis and their electronic properties as a function of temperature and magnetic field. Chapter 5 is dedicated to aligned single-walled carbon nanotubes (SWNTs) on synthesis with rational control of position and orientation, detailed characterization and construction of scaled top-gated transistors. This chapter presents a way to produce the p- and n-type nanotube transistors based on gate voltage polarity control during electrical breakdown. Finally, chapter 6 summarizes the above discussions and proposes some suggestions for future studies.

  12. Enhanced magnetocaloric effect in quasi-one-dimensional S = 1/2 Heisenberg antiferromagnet [Cu(dmen){sub 2}(H{sub 2}O)]SiF{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Orendáč, M., E-mail: martin.orendac@upjs.sk; Čižmár, E.; Orendáčová, A.; Tkáčová, J.; Kuchár, J.; Černák, J.

    2014-02-15

    Highlights: • Low-dimensional magnetic behavior was found in [Cu(dmen){sub 2}(H{sub 2}O)]SiF{sub 6}. • Enhanced magnetocaloric effect occurs at low enough temperatures (T ≪ J/k{sub B}). • The isothermal change of entropy can be 20 times larger than that in paramagnet. -- Abstract: The results of specific heat and electron-spin resonance of [Cu(dmen){sub 2}(H{sub 2}O)]SiF{sub 6} (dmen = N,N-dimethyl-1,2-diaminoethane) are reported. The studied material can be considered as an S = 1/2 quasi-one-dimensional Heisenberg antiferromagnet with dominant intrachain interaction J{sub intra}/k{sub B} = −3.59 K. The appearance of both normal and inverse magnetocaloric effect in various field ranges below saturation field B{sub sat} is tentatively attributed to weaker ferromagnetic interchain interactions. Pronounced magnetocaloric effect is found in the vicinity of B{sub sat,} where at temperatures T ≪ |J{sub intra}/k{sub B}|, the isothermal change of entropy was found to be about 20 times higher than that in S = 1/2 paramagnet. The potential origin of the observed behavior is discussed.

  13. Nucleation and growth of nanoscaled one-dimensional materials

    Science.gov (United States)

    Cui, Hongtao

    Nanoscaled one-dimensional materials have attracted great interest due to their novel physical and chemical properties. The purpose of this dissertation is to study the nucleation and growth mechanisms of carbon nanotubes and silicon nitride nanowires with their field emission applications in mind. As a result of this research, a novel methodology has been developed to deposit aligned bamboo-like carbon nanotubes on substrates using a methane and ammonia mixture in microwave plasma enhanced chemical deposition. Study of growth kinetics suggests that the carbon diffusion through bulk catalyst particles controls growth in the initial deposition process. Microstructures of carbon nanotubes are affected by the growth temperature and carbon concentration in the gas phase. High-resolution transmission electron microscope confirms the existence of the bamboo-like structure. Electron diffraction reveals that the iron-based catalyst nucleates and sustains the growth of carbon nanotubes. A nucleation and growth model has been constructed based upon experimental data and observations. In the study of silicon nitride nanoneedles, a vapor-liquid-solid model is employed to explain the nucleation and growth processes. Ammonia plasma etching is proposed to reduce the size of the catalyst and subsequently produce the novel needle-like nanostructure. High-resolution transmission electron microscope shows the structure is well crystallized and composed of alpha-silicon nitride. Other observations in the structure are also explained.

  14. Trapped Atoms in One-Dimensional Photonic Crystals

    Science.gov (United States)

    Kimble, H.

    2013-05-01

    I describe one-dimensional photonic crystals that support a guided mode suitable for atom trapping within a unit cell, as well as a second probe mode with strong atom-photon interactions. A new hybrid trap is analyzed that combines optical and Casimir-Polder forces to form stable traps for neutral atoms in dielectric nanostructures. By suitable design of the band structure, the atomic spontaneous emission rate into the probe mode can exceed the rate into all other modes by more than tenfold. The unprecedented single-atom reflectivity r0 ~= 0 . 9 for the guided probe field could create new scientific opportunities, including quantum many-body physics for 1 D atom chains with photon-mediated interactions and high-precision studies of vacuum forces. Towards these goals, my colleagues and I are pursuing numerical simulation, device fabrication, and cold-atom experiments with nanoscopic structures. Funding is provided by by the IQIM, an NSF PFC with support of the Moore Foundation, by the AFOSR QuMPASS MURI, by the DoD NSSEFF program (HJK), and by NSF Grant PHY0652914 (HJK). DEC acknowledges funding from Fundacio Privada Cellex Barcelona.

  15. Hydrothermal growth of ZnO nanostructures - revew article

    Directory of Open Access Journals (Sweden)

    Sunandan Baruah and Joydeep Dutta

    2009-01-01

    Full Text Available One-dimensional nanostructures exhibit interesting electronic and optical properties due to their low dimensionality leading to quantum confinement effects. ZnO has received lot of attention as a nanostructured material because of unique properties rendering it suitable for various applications. Amongst the different methods of synthesis of ZnO nanostructures, the hydrothermal method is attractive for its simplicity and environment friendly conditions. This review summarizes the conditions leading to the growth of different ZnO nanostructures using hydrothermal technique. Doping of ZnO nanostructures through hydrothermal method are also highlighted.

  16. Properties of ground state and anomalous quantum fluctuations in one-dimensional polaron-soliton ystems——the effects of electron-two-phonon interaction and non-adiabatic quantum correlations

    Institute of Scientific and Technical Information of China (English)

    Luo Zhi-Hua; Cao Xi-Jin; Yu Chao-Fan

    2011-01-01

    Based on the Holstein model Hamiltonian of one-dimensional molecular crystals, by making use of the expansion approach of the correlated squeezed-coherent states of phonon instead of the two-phonon coherent state expansion scheme, the properties of the ground state and the anomalous quantum fluctuations are investigated in a strongly coupled electron-phonon system with special consideration of the electron-two-phonon interaction. The effective renormalization ((~α)i) of the displacement of the squeezed phonons with the effect of the squeezed-coherent states of phonon and both the electron-displaced phonon and the polaron-squeezed phonon correlations have been combined to obtain the anomalous quantum fluctuations for the corrections of the coherent state. Due to these non-adiabatic correlations, the effective displacement parameter (~α)i is larger than the ordinary parameter αi(0). In comparison with the electron-one-phonon interaction (g) corrected as (~α)ig, we have found the electron-two-phonon interaction (g1) corrected as (~α)2ig1 is enhanced significantly. For this reason, the ground state energy (EO(2)) contributed by the electron-two-phonon interaction is more negative than the single-phonon case (EO(1)) and the soliton solution is more stable. At the same time, the effects of the electron-two-phonon interaction greatly increase the polaron energy and the quantum fluctuations. Furthermore,in a deeper level, we have considered the effect of the polaron-squeezed phonon correlation (f-correlation). Since this correlation parameter f > 1, this effect will strengthen the electron-one and two-phonon interactions by f(~α)ig and f2( ~α)2i1, respectively. The final results show that the ground state energy and the polaron energy will appear more negative further and the quantum fluctuations will gain further improvement.

  17. Spiral Magnetic Order in the One-Dimensional Kondo Lattice

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen-Rong; LI Zheng-Zhong; SHEN Rui

    2001-01-01

    The effects of c-f (conduction-f electrons) hybridization on the spiral spin magnetism in the one dimensional Kondo lattice are studied. By using the mean-field approximation, a close set of equations of the Green's functions with arbitrary wave vector Q for the spiral ordering of spins is deduced. The magnetic phase boundary between the spiral magnetism and ferromagnetism has been calculated approximately. From our qualitative results, one can find that the ferromagnetic region is enlarged due to the c f hybridization. Moreover, some new results reflecting the Kondo effect, such as the modified dispersion relation and the weakening of the localized magnetic moments are also obtained.

  18. Hydrogen peroxide stabilization in one-dimensional flow columns

    Science.gov (United States)

    Schmidt, Jeremy T.; Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.

    2011-09-01

    Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H 2O 2 propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO.

  19. Synthesis and Characterization of One-dimensional and Two-Dimensional Porphyrin Polymers* (Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Porphyrin polymers are of interest in relation to conductive materials[1, 2], catalysts for photosynthetic charge separation[3], or the fundamental features in biological systems[4]. There have been many versatile studies about them[5,6]. The one-dimensional “Shish Kebab” porphyrin polymers synthesized with a new method different from those reported and Schiff base porphyrin polymers with two-dimensional nano-structure have provided a new field of study. The present paper covers highly ordered porphyrin polymers.

  20. Universality of anomalous one-dimensional heat conductivity

    Science.gov (United States)

    Lepri, Stefano; Livi, Roberto; Politi, Antonio

    2003-12-01

    In one and two dimensions, transport coefficients may diverge in the thermodynamic limit due to long-time correlation of the corresponding currents. The effective asymptotic behavior is addressed with reference to the problem of heat transport in one-dimensional crystals, modeled by chains of classical nonlinear oscillators. Extensive accurate equilibrium and nonequilibrium numerical simulations confirm that the finite-size thermal conductivity diverges with system size L as κ∝Lα. However, the exponent α deviates systematically from the theoretical prediction α=1/3 proposed in a recent paper [O. Narayan and S. Ramaswamy, Phys. Rev. Lett. 89, 200601 (2002)].

  1. Lateral shift in one-dimensional quasiperiodic chiral photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Da, Jian, E-mail: dajian521@sina.com [Department of Information Engineering, Huaian Senior Vocational and Technical School, Feiyao road, Huaian 223005, Jiangsu Province (China); Mo, Qi, E-mail: moqiyueyang@163.com [School of Software, Yunnan University, Cuihu Bai Road, Kunming City, Yunnan Province 650091 (China); Cheng, Yaokun [Department of Information Engineering, Huaian Senior Vocational and Technical School, Feiyao road, Huaian 223005, Jiangsu Province (China); Liu, Taixiang [Taishan Vocational College of Nursing, Shandong Province 271000 (China)

    2015-02-01

    We investigate the lateral shift of a one-dimensional quasiperiodic photonic crystal consisting of chiral and conventional dielectric materials. The effect of structural irregularity on lateral shift is evaluated by stationary-phase approach. Our results show that the lateral shift can be modulated by varying the structural irregularity in quasiperiodic structure. Besides, the position of peak in lateral shift spectrum stays sensitive to the chiral factor of chiral materials. In comparison with that of periodic structure, quasiperiodic structure provides an extra degree of freedom to manipulate the lateral shift.

  2. 箱型梁附加挠度与剪力滞效应的一维有限元分析%One-dimensional finite element analysis on additional deflection and shear-lag effect of box-girders

    Institute of Scientific and Technical Information of China (English)

    杨绿峰; 周月娥; 曾有凤

    2013-01-01

    当前箱型梁剪力滞效应分析的一维离散有限元法对剪力滞函数的处理存在局限性,而且剪力滞系数难以准确反映翼缘截面剪力滞效应及其变化规律.为此,利用箱梁附加挠度代替剪力滞函数建立箱梁翼缘的纵向位移函数,并根据能量变分原理建立控制微分方程并识别了其中的待定参数.以箱梁挠度、附加挠度及其一阶导数作为单元节点位移参数,提出了箱型梁剪力滞效应分析的一维离散有限元法,给出了箱梁的自然边界条件和强迫边界条件.基于箱梁挠度和附加挠度定义了新的剪力滞系数,分析了不同支撑条件对箱型梁剪力滞效应的影响.算例分析证明了该方法的有效性,且具有较高的计算精度;与传统的基于应力的剪力滞系数相比,基于挠度的剪力滞系数能够更加准确地反映箱型梁截面的剪力滞效应及其分布规律.%The shear-lag function in one-dimensional finite element method for box-girders has no definite physical interpretation, and moreover the shear-lag coefficient can not reflect correctly the shear-lag effect and its variation along the axis of box girder. In order to circumvent these problems, the additional deflection function instead of the shear-lag function is incorporated in the longitudinal displacement of the flange of the box girder. The variational principle is employed to identify the undetermined constants in the longitudinal displacement function. Furthermore, the deflection, additional deflection and their first derivatives are adopted as nodal displacement parameters in the discreted finite elements of box-girder, leading to one-dimensional finite element method for the shear-lag effect of box girders. A new shear-lag coefficient is defined in terms of the deflection of the box-girder, based on which the shear-lag effect on box girders is analysed with different boundary conditions considered. Examples show that the shear

  3. Nanostructures having high performance thermoelectric properties

    Science.gov (United States)

    Yang, Peidong; Majumdar, Arunava; Hochbaum, Allon I; Chen, Renkun; Delgado, Raul Diaz

    2014-05-20

    The invention provides for a nanostructure, or an array of such nanostructures, each comprising a rough surface, and a doped or undoped semiconductor. The nanostructure is an one-dimensional (1-D) nanostructure, such a nanowire, or a two-dimensional (2-D) nanostructure. The nanostructure can be placed between two electrodes and used for thermoelectric power generation or thermoelectric cooling.

  4. MARCUSE’S ONE-DIMENSIONAL SOCIETY IN ONE-DIMENSIONAL MAN

    Directory of Open Access Journals (Sweden)

    MILOS RASTOVIC

    2013-05-01

    Full Text Available Nowadays, Marcuse’s main book One-Dimensional Man is almost obsolete, or rather passé. However, there are reasons to renew the reading of his book because of “the crisis of capitalism,” and the prevailing framework of technological domination in “advanced industrial society” in which we live today. “The new forms of control” in “advanced industrial societies” have replaced traditional methods of political and economic administration. The dominant structural element of “advanced industrial society” has become a technical and scientific apparatus of production and distribution of technology and administrative practice based on application of impersonal rules by a hierarchy of associating authorities. Technology has been liberated from the control of particular interests, and it has become the factor of domination in itself. Technological domination stems from the technical development of the productive apparatus that reproduces its ability into all spheres of social life (cultural, political, and economic. Based upon this consideration, in this paper, I will examine Marcuse’s ideas of “the new forms of control,” which creates a one–dimensional society. Marcuse’s fundamental thesis in One-Dimensional Man is that technological rationality is the most dominant factor in an “advanced industrial society,” which unites two earlier opposing forces of dissent: the bourgeoisie and the proletariat.

  5. Bjorken flow in one-dimensional relativistic magnetohydrodynamics with magnetization

    Science.gov (United States)

    Pu, Shi; Roy, Victor; Rezzolla, Luciano; Rischke, Dirk H.

    2016-04-01

    We study the one-dimensional, longitudinally boost-invariant motion of an ideal fluid with infinite conductivity in the presence of a transverse magnetic field, i.e., in the ideal transverse magnetohydrodynamical limit. In an extension of our previous work Roy et al., [Phys. Lett. B 750, 45 (2015)], we consider the fluid to have a nonzero magnetization. First, we assume a constant magnetic susceptibility χm and consider an ultrarelativistic ideal gas equation of state. For a paramagnetic fluid (i.e., with χm>0 ), the decay of the energy density slows down since the fluid gains energy from the magnetic field. For a diamagnetic fluid (i.e., with χmlaw ˜τ-a, two distinct solutions can be found depending on the values of a and χm. Finally, we also solve the ideal magnetohydrodynamical equations for one-dimensional Bjorken flow with a temperature-dependent magnetic susceptibility and a realistic equation of state given by lattice-QCD data. We find that the temperature and energy density decay more slowly because of the nonvanishing magnetization. For values of the magnetic field typical for heavy-ion collisions, this effect is, however, rather small. It is only for magnetic fields about an order of magnitude larger than expected for heavy-ion collisions that the system is substantially reheated and the lifetime of the quark phase might be extended.

  6. Effects of spatial confinement on conduction electrons in semiconductor nanostructures

    NARCIS (Netherlands)

    Germeau, Alexander

    2003-01-01

    Semiconductor nanostructures show electrical and optical properties which can be very different from bulk semiconductors. The various effects that occur due to the spatial confinement of electrons in such structures are of scientific importance. In addition, semiconductor nanostructures are very pro

  7. Gibbs measures and phase transitions in one-dimensional models

    OpenAIRE

    Mallak, Saed

    2000-01-01

    Ankara : Department of Mathematics and the Institute of Engineering and Sciences of Bilkent University, 2000. Thesis (Ph.D.) -- Bilkent University, 2000. Includes bibliographical references leaves 63-64 In this thesis we study the problem of limit Gibbs measures in one-dimensional models. VVe investigate uniqueness conditions for the limit Gibbs measures for one-dimensional models. VVe construct a one-dimensional model disproving a uniqueness conjecture formulated before for...

  8. 新型一维碳基纳米材料的自旋热电效应%Spin Thermoelectric Effects of New-style One-dimensional Carbon-based Naomaterials

    Institute of Scientific and Technical Information of China (English)

    刘玉申; 冯金福; 王雪峰

    2015-01-01

    基于第一性原理的方法,从原子层面上研究了锯齿型石墨烯纳米条带与碳链以及石墨烯纳米片组成的一维碳基纳米材料的自旋热电性能.研究发现在费米面处自旋向下的传输函数压抑至零,而自旋向上的传输函数大约为0.25,具有理想的半金属性质.另外声子部分热导明显小于对应的电子部分热导.同时低温区域(80 K附近)自旋Seebeck系数明显得到加强,导致了电荷和自旋热电品质因子接近40.并且在室温区域,自旋热电品质因子明显大于对应的电荷热电品质因子.%Based on first-principles methods, the authors of this paper investigate spin thermoelectric effects of one-dimensional spin-based devices consisting of zigzag-edged graphene nanoribbons (ZGNRs), carbon chains and graphene nanoflake. It is found that the spin-down transmission function is suppressed to zero, while the spin-up transmission function is about 0.25. Therefore, an ideal half-metallic property is achieved. In addition, the phonon thermal conductance is obviously smaller than the electronic thermal conductance. Meantime, the spin Seebeck effects are obviously enhanced at the low-temperature regime (about 80K), resulting in the fact that spin thermoelectric figure of merit can reach about 40. Moreover, the spin thermoelectric figure of merit is always larger than the corresponding charge thermoelectric figure of merit. Therefore, the study shows that they can be used to prepare the ideal thermospin devices.

  9. The Progress of Photoluminescent Properties of Rare-Earth-Ions-Doped Phosphate One-Dimensional Nanocrystals

    Directory of Open Access Journals (Sweden)

    Lixin Yu

    2010-01-01

    Full Text Available One-dimensional (1D nanostructures, such as tubes, wires, rods, and belts, have aroused remarkable attentions over the past decade due to a great deal of potential applications, such as data storage, advanced catalyst, and photoelectronic devices . On the other hand, in comparison with zero-dimensional (0D nanostructures, the space anisotropy of 1D structures provided a better model system to study the dependence of electronic transport, optical and mechanical properties on size confinement and dimensionality. Rare earth (RE compounds, were intensively applied in luminescent and display devices. It is expected that in nanosized RE compounds the luminescent quantum efficiency (QE and display resolution could be improved. In this paper, we systematically reported the research progress of luminescent properties of RE-doped 1D orthophosphate nanocrystal, including the synthesis of 1D nanostructures doped with RE ions, local symmetry of host, electronic transition processes, energy transfer (ET, and so forth.

  10. Analytical models of optical response in one-dimensional semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Thomas Garm, E-mail: tgp@nano.aau.dk

    2015-09-04

    The quantum mechanical description of the optical properties of crystalline materials typically requires extensive numerical computation. Including excitonic and non-perturbative field effects adds to the complexity. In one dimension, however, the analysis simplifies and optical spectra can be computed exactly. In this paper, we apply the Wannier exciton formalism to derive analytical expressions for the optical response in four cases of increasing complexity. Thus, we start from free carriers and, in turn, switch on electrostatic fields and electron–hole attraction and, finally, analyze the combined influence of these effects. In addition, the optical response of impurity-localized excitons is discussed. - Highlights: • Optical response of one-dimensional semiconductors including excitons. • Analytical model of excitonic Franz–Keldysh effect. • Computation of optical response of impurity-localized excitons.

  11. Solitons in one-dimensional photonic crystals

    CERN Document Server

    Mayteevarunyoo, Thawatchai

    2008-01-01

    We report results of a systematic analysis of spatial solitons in the model of 1D photonic crystals, built as a periodic lattice of waveguiding channels, of width D, separated by empty channels of width L-D. The system is characterized by its structural "duty cycle", DC = D/L. In the case of the self-defocusing (SDF) intrinsic nonlinearity in the channels, one can predict new effects caused by competition between the linear trapping potential and the effective nonlinear repulsive one. Several species of solitons are found in the first two finite bandgaps of the SDF model, as well as a family of fundamental solitons in the semi-infinite gap of the system with the self-focusing nonlinearity. At moderate values of DC (such as 0.50), both fundamental and higher-order solitons populating the second bandgap of the SDF model suffer destabilization with the increase of the total power. Passing the destabilization point, the solitons assume a flat-top shape, while the shape of unstable solitons gets inverted, with loc...

  12. Strongly interacting photons in one-dimensional continuum

    CERN Document Server

    Roy, Dibyendu; Firstenberg, Ofer

    2016-01-01

    The photon-photon scattering in vacuum is extremely weak. However, strong effective interactions between single photons can be realized by employing strong light-matter coupling. These interactions are a fundamental building block for quantum optics, bringing many-body physics to the photonic world and providing important resources for quantum photonic devices and for optical metrology. In this Colloquium, we review the physics of strongly-interacting photons in one-dimensional systems with no optical confinement along the propagation direction. We focus on two recently-demonstrated experimental realizations: (i) superconducting qubits coupled to open transmission lines, and (ii) interacting Rydberg atoms in a cold gas. Advancements in the theoretical understanding of these systems are presented in complementary formalisms and compared to experimental results. The experimental achievements are summarized alongside of a systematic description of the quantum optical effects and quantum devices emerging from the...

  13. One dimensional Convolutional Goppa Codes over the projective line

    CERN Document Server

    Pérez, J A Domínguez; Sotelo, G Serrano

    2011-01-01

    We give a general method to construct MDS one-dimensional convolutional codes. Our method generalizes previous constructions of H. Gluesing-Luerssen and B. Langfeld. Moreover we give a classification of one-dimensional Convolutional Goppa Codes and propose a characterization of MDS codes of this type.

  14. One-dimensional diffusion model in an Inhomogeneous region

    CSIR Research Space (South Africa)

    Fedotov, I

    2006-01-01

    Full Text Available A one-dimensional model is developed to describe atomic diffusion in a graphite tube atomizer for electrothermal atomic adsorption spectrometry. The underlying idea of the model is the solution of an inhomogeneous one-dimensional diffusion equation...

  15. Facile synthesis of highly efficient one-dimensional plasmonic photocatalysts through Ag@Cu₂O core-shell heteronanowires.

    Science.gov (United States)

    Xiong, Jinyan; Li, Zhen; Chen, Jun; Zhang, Shanqing; Wang, Lianzhou; Dou, Shixue

    2014-09-24

    A novel class of one-dimensional (1D) plasmonic Ag@Cu2O core-shell heteronanowires have been synthesized at room temperature for photocatalysis application. The morphology, size, crystal structure and composition of the products were investigated by XRD, SEM, TEM, XPS, and UV-vis instruments. It was found the reaction time and the amount of Ag nanowires play crucial roles in the formation of well-defined 1D Ag@Cu2O core-shell heteronanowires. The resultant 1D Ag@Cu2O NWs exhibit much higher photocatalytic activity toward degradation of organic contaminants than Ag@Cu2O core-shell nanoparticles or pure Cu2O nanospheres under solar light irradiation. The drastic enhancement in photocatalytic activity could be attributed to the surface plasmon resonance and the electron sink effect of the Ag NW cores, and the unique 1D core-shell nanostructure.

  16. One-dimensional long-range percolation: A numerical study

    Science.gov (United States)

    Gori, G.; Michelangeli, M.; Defenu, N.; Trombettoni, A.

    2017-07-01

    In this paper we study bond percolation on a one-dimensional chain with power-law bond probability C /rd +σ , where r is the distance length between distinct sites and d =1 . We introduce and test an order-N Monte Carlo algorithm and we determine as a function of σ the critical value Cc at which percolation occurs. The critical exponents in the range 0 introduction of a suitably defined effective dimension deff relating the long-range model with a short-range one in dimension deff. We finally present a formulation of our algorithm for bond percolation on general graphs, with order N efficiency on a large class of graphs including short-range percolation and translationally invariant long-range models in any spatial dimension d with σ >0 .

  17. A Reduced Order, One Dimensional Model of Joint Response

    Energy Technology Data Exchange (ETDEWEB)

    DOHNER,JEFFREY L.

    2000-11-06

    As a joint is loaded, the tangent stiffness of the joint reduces due to slip at interfaces. This stiffness reduction continues until the direction of the applied load is reversed or the total interface slips. Total interface slippage in joints is called macro-slip. For joints not undergoing macro-slip, when load reversal occurs the tangent stiffness immediately rebounds to its maximum value. This occurs due to stiction effects at the interface. Thus, for periodic loads, a softening and rebound hardening cycle is produced which defines a hysteretic, energy absorbing trajectory. For many jointed sub-structures, this hysteretic trajectory can be approximated using simple polynomial representations. This allows for complex joint substructures to be represented using simple non-linear models. In this paper a simple one dimensional model is discussed.

  18. Spin accumulation on a one-dimensional mesoscopic Rashba ring

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhiyong [Department of Physics, Nanjing University, Nanjing 210093 (China)

    2006-04-26

    The nonequilibrium spin accumulation on a one-dimensional (1D) mesoscopic Rashba ring is investigated with unpolarized current injected through ideal leads. Due to the Rashba spin-orbit (SO) coupling and back-scattering at the interfaces between the leads and the ring, a beating pattern is formed in the fast oscillation of spin accumulation. If every beating period is complete, a plateau is formed, where the variation of spin accumulation with the external voltage is slow, but if new incomplete periods emerge in the envelope function, a transitional region appears. This plateau structure and the beating pattern are related to the tunnelling through spin-dependent resonant states. Because of the Aharonov-Casher (AC) effect, the average spin accumulation oscillates quasi-periodically with the Rashba SO coupling and has a series of zeros. In some situations, the direction of the average spin accumulation can be reversed by the external voltage in this 1D Rashba ring.

  19. Spin accumulation on a one-dimensional mesoscopic Rashba ring.

    Science.gov (United States)

    Zhang, Zhi-Yong

    2006-04-26

    The nonequilibrium spin accumulation on a one-dimensional (1D) mesoscopic Rashba ring is investigated with unpolarized current injected through ideal leads. Due to the Rashba spin-orbit (SO) coupling and back-scattering at the interfaces between the leads and the ring, a beating pattern is formed in the fast oscillation of spin accumulation. If every beating period is complete, a plateau is formed, where the variation of spin accumulation with the external voltage is slow, but if new incomplete periods emerge in the envelope function, a transitional region appears. This plateau structure and the beating pattern are related to the tunnelling through spin-dependent resonant states. Because of the Aharonov-Casher (AC) effect, the average spin accumulation oscillates quasi-periodically with the Rashba SO coupling and has a series of zeros. In some situations, the direction of the average spin accumulation can be reversed by the external voltage in this 1D Rashba ring.

  20. Polaron and bipolaron of uniaxially strained one dimensional zigzag ladder

    Energy Technology Data Exchange (ETDEWEB)

    Yavidov, B.Ya., E-mail: bakhrom.yavidov@gmail.com

    2016-09-15

    An influence of the uniaxial strains in one dimensional zigzag ladder (1DZL) on the properties of polarons and bipolarons is considered. It is shown that strain changes all the parameters of the system, in particular, spectrum, existing bands and the masses of charge carriers. Numerical results obtained by taking into an account the Poisson effect clearly indicate that the properties of the (bi)polaronic system can be tuned via strain. Mass of bipolaron can be manipulated by the strain too which in turn leads to the way of tuning Bose–Einstein condensation temperature T{sub BEC} of bipolarons. It is shown that T{sub BEC} of bipolarons in strained 1DZL reasonably correlates with the values of critical temperature of superconductivity of certain perovskites.

  1. One-dimensional photonic crystal fishbone hybrid nanocavity with nanoposts

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Tsan-Wen; Lin, Pin-Tso; Lee, Po-Tsung, E-mail: potsung@mail.nctu.edu.tw [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Rm. 413 CPT Building, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan (China)

    2014-05-12

    We propose and investigate a one-dimensional photonic crystal (PhC) fishbone (FB) hybrid nanocavity lying on silver substrate with a horizontal air slot. With very few PhC periods, the confined transverse-magnetic, TM{sub 10} hybrid mode concentrated within the air slot shows high quality factor over effective mode volume ratio larger than 10{sup 5}λ{sup −3}. Most importantly, this FB hybrid nanocavity allows formation of low-index nanoposts within the air slot without significantly affecting the mode properties. These nanoposts guarantee the structural stabilities under different environmental perturbations. Furthermore, capabilities of our proposed design in serving as optical sensors and tweezers for bio-sized nanoparticles are also investigated.

  2. Reprint of : Absorbing/Emitting Phonons with one dimensional MOSFETs

    Science.gov (United States)

    Bosisio, Riccardo; Gorini, Cosimo; Fleury, Geneviève; Pichard, Jean-Louis

    2016-08-01

    We consider nanowires in the field effect transistor device configuration. Modeling each nanowire as a one dimensional lattice with random site potentials, we study the heat exchanges between the nanowire electrons and the substrate phonons, when electron transport is due to phonon-assisted hops between localized states. Shifting the nanowire conduction band with a metallic gate induces different behaviors. When the Fermi potential is located near the band center, a bias voltage gives rise to small local heat exchanges which fluctuate randomly along the nanowire. When it is located near one of the band edges, the bias voltage yields heat currents which flow mainly from the substrate towards the nanowire near one boundary of the nanowire, and in the opposite direction near the other boundary. This opens interesting perspectives for heat management at submicron scales: arrays of parallel gated nanowires could be used for a field control of phonon emission/absorption.

  3. 一维掺杂光子晶体结构参数对带隙结构影响%Effect of Structure Parameter of One Dimensional Doped Photonic Crystal on Photonic Band Gap Structure

    Institute of Scientific and Technical Information of China (English)

    郭立帅

    2012-01-01

    The properties of band - gap of one - dimensional doped photonic crystal are studied by using numerical- ly method based on the transfer matrix method. The result shows that a narrow conduction band appears in the cen- tre of forbidden band in one - dimensional doped photonic crystal. The depth of conduction band appears in the centre of forbidden band has a maximum, which was caused by the number of layers of the second half of impurity where the first one was fixed. It shows that the forbidden band center's conduction band depth was still biggest by means of changing basic level thickness.%基于传输矩阵法,数值研究了掺杂一维光子晶体带隙特征。研究表明:一维掺杂光晶体禁带中心位置出现一个极窄的导带,当杂质前半部分层数给定时,后半部分总存在一个层数,使得禁带中心导带的深度达到最大,在此基础上通过改变基本层厚度发现,禁带中心的导带深度仍然最大,我们可以通过改变基本层厚度厚度,让特定波长的光顺利通过。

  4. Twisting phonons in complex crystals with quasi-one-dimensional substructures.

    Science.gov (United States)

    Chen, Xi; Weathers, Annie; Carrete, Jesús; Mukhopadhyay, Saikat; Delaire, Olivier; Stewart, Derek A; Mingo, Natalio; Girard, Steven N; Ma, Jie; Abernathy, Douglas L; Yan, Jiaqiang; Sheshka, Raman; Sellan, Daniel P; Meng, Fei; Jin, Song; Zhou, Jianshi; Shi, Li

    2015-04-15

    A variety of crystals contain quasi-one-dimensional substructures, which yield distinctive electronic, spintronic, optical and thermoelectric properties. There is a lack of understanding of the lattice dynamics that influences the properties of such complex crystals. Here we employ inelastic neutron scatting measurements and density functional theory calculations to show that numerous low-energy optical vibrational modes exist in higher manganese silicides, an example of such crystals. These optical modes, including unusually low-frequency twisting motions of the Si ladders inside the Mn chimneys, provide a large phase space for scattering acoustic phonons. A hybrid phonon and diffuson model is proposed to explain the low and anisotropic thermal conductivity of higher manganese silicides and to evaluate nanostructuring as an approach to further suppress the thermal conductivity and enhance the thermoelectric energy conversion efficiency. This discovery offers new insights into the structure-property relationships of a broad class of materials with quasi-one-dimensional substructures for various applications.

  5. Interface phonon effect on optical spectra of quantum nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Maslov, Alexander Yu., E-mail: maslov.ton@mail.ioffe.r [Ioffe Physical Technical Institute, Polytechnicheskaya st., 26, 194021 Saint Petersburg (Russian Federation); Proshina, Olga V.; Rusina, Anastasia N. [Ioffe Physical Technical Institute, Polytechnicheskaya st., 26, 194021 Saint Petersburg (Russian Federation)

    2009-12-15

    This paper deals with theory of large radius polaron effect in quantum wells, wires and dots. The interaction of charge particles and excitons with both bulk and interface optical phonons is taken into consideration. The analytical expression for polaron binding energy is obtained for different types of nanostructures. It is shown that the contribution of interface phonons to the polaron binding energy may exceed the bulk phonon part. The manifestation of polaron effects in optical spectra of quantum nanostructures is discussed.

  6. Quantum mechanical effects analysis of nanostructured solar cell models

    Directory of Open Access Journals (Sweden)

    Badea Andrei

    2016-01-01

    Full Text Available The quantum mechanical effects resulted from the inclusion of nanostructures, represented by quantum wells and quantum dots, in the i-layer of an intermediate band solar cell will be analyzed. We will discuss the role of these specific nanostructures in the increasing of the solar cells efficiency. InAs quantum wells being placed in the i-layer of a gallium arsenide (GaAs p-i-n cell, we will analyze the quantum confined regions and determine the properties of the eigenstates located therein. Also, we simulate the electroluminescence that occurs due to the nanostructured regions.

  7. Debye screening length effects of nanostructured materials

    CERN Document Server

    Ghatak, Kamakhya Prasad

    2014-01-01

    This monograph solely investigates the Debye Screening Length (DSL) in semiconductors and their nano-structures. The materials considered are quantized structures of non-linear optical, III-V, II-VI, Ge, Te, Platinum Antimonide, stressed materials, Bismuth, GaP, Gallium Antimonide, II-V and Bismuth Telluride respectively. The DSL in opto-electronic materials and their quantum confined counterparts is studied in the presence of strong light waves and intense electric fields on the basis of newly formulated electron dispersion laws that control the studies of such quantum effect devices. The suggestions for the experimental determination of 2D and 3D DSL and the importance of measurement of band gap in optoelectronic materials under intense built-in electric field in nano devices and strong external photo excitation (for measuring photon induced physical properties) have also been discussed in this context. The influence of crossed electric and quantizing magnetic fields on the DSL and the DSL in heavily doped ...

  8. A NEW ONE-DIMENSIONAL CHAOTIC MAP WITH INFINITE COLLAPSES

    Institute of Scientific and Technical Information of China (English)

    Qiu Yuehong; He Chen; Zhu Hongwen

    2002-01-01

    This letter presents a new one-dimensional chaotic map with infinite collapses. Theoretical analyses show that the map has complicated dynamical behavior and ideal distribution.The map can be applied in chaotic spreading spectrum communication and chaotic cipher.

  9. One-dimensional spatially dependent solute transport in semi ...

    African Journals Online (AJOL)

    One-dimensional spatially dependent solute transport in semi-infinite porous media: an analytical solution. ... Journal Home > Vol 9, No 4 (2017) > ... In this mathematical model the dispersion coefficient is considered spatially dependent while ...

  10. One-Dimensional Tunable Photonic-Crystal IR Filter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — MetroLaser proposes to design and develop an innovative narrowband tunable IR filter based on the properties of a one-dimensional photonic crystal structure with a...

  11. One-Dimensional Tunable Photonic-Crystal IR Filter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — MetroLaser proposes to design and develop an innovative narrowband tunable IR filter based on the properties of a one-dimensional photonic crystal structure with a...

  12. Synthesis and Characterization of One-dimensional and Two-Dimensional Porphyrin Polymers* (

    Institute of Scientific and Technical Information of China (English)

    LI; Xiang-qing

    2001-01-01

    Porphyrin polymers are of interest in relation to conductive materials[1, 2], catalysts for  photosynthetic charge separation[3], or the fundamental features in biological systems[4].There have been many versatile studies about them[5,6]. The one-dimensional “Shish Kebab”porphyrin polymers synthesized with a new method different from those reported and Schiff base porphyrin polymers with two-dimensional nano-structure have provided a new field of study. The present paper covers highly ordered porphyrin polymers.……

  13. Fidelity of an electron in one-dimensional determined potentials

    Institute of Scientific and Technical Information of China (English)

    Song Wen-Guang; Tong Pei-Qing

    2009-01-01

    We numerically study the fidelity of an electron in the one-dimensional Harper model and in the one-dimensional slowly varying potential model. Our results show that many properties of the two models can be well reflected by the fidelity: (i) the mobility edge and metal-insulator transition can be characterized by the static fidelity; (ii) the extended state and localized state can be identified by the dynamic fidelity. Therefore, it may broaden the applied areas of the fidelity.

  14. Effects of gradient disorder on electronic transport in quasi-one-dimensional nanowires%准一维纳米线电子输运的梯度无序效应

    Institute of Scientific and Technical Information of China (English)

    段玲; 胡飞; 丁建文

    2011-01-01

    考虑实际体系的梯度无序和结散射,发展格林函数矩阵分解消元方法,研究了准一维纳米线的电子输运性质.结果表明,由于结散射,电导随能量呈现振荡行为,无序的引入破坏了电子相干性,在低无序度区平均电导呈现异常增加,呈现一个新的电导峰.当表面存在无序但无梯度衰减时,体系的平均电导随无序度增强先减后增,出现类局域—退局域性转变.当表面无序线性衰减时,平均电导在强无序区稍有增加,而当表面无序高斯型衰减时,平均电导指数衰减,类局域—退局域性转变消失,不同于以前的理论预言.研究结果对准一维纳米线电子器件的结构设计和应用有指导作用.%Considering both the gradient decay of the real disorder and the contact scattering,we investigate the electronic transport in quasi-one-dimensional nanowires by developing a decomposition elimination method for Green's function matrix.In the presence the contact scattering,the conductance oscillates with energy.For some energies of incident electrons,an abnormal enhancement is obtained in the average conductance due to the destroyed coherence by the introduction of much low disorder,showing that there appears a new conductance peak.In the absence of disorder gradient,the average conductance firstly decreases then increases with disorder strength,indicating that there exists a localization-delocalization transition.In the presence of linearly decaying disorder,the average conductance increases slightly in a strong disorder region.In the case of the Gaussian-type decaying disorder,the average conductance decreases exponentially and the localization-delocalization transition disappears,which is different from previous thereotical result.The results are helpful for the design and the application of quasi-one-dimensional nanowires device.

  15. Negative refraction angular characterization in one-dimensional photonic crystals.

    Directory of Open Access Journals (Sweden)

    Jesus Eduardo Lugo

    Full Text Available BACKGROUND: Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity developed here. We also analytically derived the negative refraction correctness condition that gives the angular region where negative refraction occurs. METHODOLOGY/PRINCIPAL FINDINGS: By using standard photonic techniques we experimentally determined the relationship between incidence and negative refraction angles and found the negative refraction range by applying the correctness condition. In order to compare both theories with experimental results an output refraction correction was utilized. The correction uses Snell's law and an effective refractive index based on two effective dielectric constants. We found good agreement between experiment and both theories in the negative refraction zone. CONCLUSIONS/SIGNIFICANCE: Since both theories and the experimental observations agreed well in the negative refraction region, we can use both negative refraction theories plus the output correction to predict negative refraction angles. This can be very useful from a practical point of view for space filtering applications such as a photonic demultiplexer or for sensing applications.

  16. Negative refraction angular characterization in one-dimensional photonic crystals.

    Science.gov (United States)

    Lugo, Jesus Eduardo; Doti, Rafael; Faubert, Jocelyn

    2011-04-06

    Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity developed here. We also analytically derived the negative refraction correctness condition that gives the angular region where negative refraction occurs. By using standard photonic techniques we experimentally determined the relationship between incidence and negative refraction angles and found the negative refraction range by applying the correctness condition. In order to compare both theories with experimental results an output refraction correction was utilized. The correction uses Snell's law and an effective refractive index based on two effective dielectric constants. We found good agreement between experiment and both theories in the negative refraction zone. Since both theories and the experimental observations agreed well in the negative refraction region, we can use both negative refraction theories plus the output correction to predict negative refraction angles. This can be very useful from a practical point of view for space filtering applications such as a photonic demultiplexer or for sensing applications.

  17. Cooperative eigenmodes and scattering in one-dimensional atomic arrays

    Science.gov (United States)

    Bettles, Robert J.; Gardiner, Simon A.; Adams, Charles S.

    2016-10-01

    Collective coupling between dipoles can dramatically modify the optical response of a medium. Such effects depend strongly on the geometry of the medium and the polarization of the light. Using a classical coupled dipole model, here we investigate the simplest case of one-dimensional arrays of interacting atomic dipoles driven by a weak laser field. Changing the polarization and direction of the driving field allows us to separately address superradiant, subradiant, redshifted, and blueshifted eigenmodes, as well as observe strong Fano-like interferences between different modes. The cooperative eigenvectors can be characterized by the phase difference between nearest-neighbor dipoles, ranging from all oscillating in phase to all oscillating out of phase with their nearest neighbors. Investigating the eigenvalue behavior as a function of atom number and lattice spacing, we find that certain eigenmodes of an infinite atomic chain have the same decay rate as a single atom between two mirrors. The effects we observe provide a framework for collective control of the optical response of a medium, giving insight into the behavior of more complicated geometries, as well as providing further evidence for the dipolar analog of cavity QED.

  18. Charge transport through one-dimensional Moiré crystals

    Science.gov (United States)

    Bonnet, Roméo; Lherbier, Aurélien; Barraud, Clément; Rocca, Maria Luisa Della; Lafarge, Philippe; Charlier, Jean-Christophe

    2016-01-01

    Moiré superlattices were generated in two-dimensional (2D) van der Waals heterostructures and have revealed intriguing electronic structures. The appearance of mini-Dirac cones within the conduction and valence bands of graphene is one of the most striking among the new quantum features. A Moiré superstructure emerges when at least two periodic sub-structures superimpose. 2D Moiré patterns have been particularly investigated in stacked hexagonal 2D atomic lattices like twisted graphene layers and graphene deposited on hexagonal boron-nitride. In this letter, we report both experimentally and theoretically evidence of superlattices physics in transport properties of one-dimensional (1D) Moiré crystals. Rolling-up few layers of graphene to form a multiwall carbon nanotube adds boundaries conditions that can be translated into interference fringes-like Moiré patterns along the circumference of the cylinder. Such a 1D Moiré crystal exhibits a complex 1D multiple bands structure with clear and robust interband quantum transitions due to the presence of mini-Dirac points and pseudo-gaps. Our devices consist in a very large diameter (>80 nm) multiwall carbon nanotubes of high quality, electrically connected by metallic electrodes acting as charge reservoirs. Conductance measurements reveal the presence of van Hove singularities assigned to 1D Moiré superlattice effect and illustrated by electronic structure calculations.

  19. Solitary Wave in One-dimensional Buckyball System at Nanoscale

    Science.gov (United States)

    Xu, Jun; Zheng, Bowen; Liu, Yilun

    2016-01-01

    We have studied the stress wave propagation in one-dimensional (1-D) nanoscopic buckyball (C60) system by molecular dynamics (MD) simulation and quantitative modeling. Simulation results have shown that solitary waves are generated and propagating in the buckyball system through impacting one buckyball at one end of the buckyball chain. We have found the solitary wave behaviors are closely dependent on the initial temperature and impacting speed of the buckyball chain. There are almost no dispersion and dissipation of the solitary waves (stationary solitary wave) for relatively low temperature and high impacting speed. While for relatively high temperature and low impacting speed the profile of the solitary waves is highly distorted and dissipated after propagating several tens of buckyballs. A phase diagram is proposed to describe the effect of the temperature and impacting speed on the solitary wave behaviors in buckyball system. In order to quantitatively describe the wave behavior in buckyball system, a simple nonlinear-spring model is established, which can describe the MD simulation results at low temperature very well. The results presented in this work may lay a solid step towards the further understanding and manipulation of stress wave propagation and impact energy mitigation at nanoscale. PMID:26891624

  20. Spin interference in silicon one-dimensional rings

    Energy Technology Data Exchange (ETDEWEB)

    Bagraev, N T [Ioffe Physico-Technical Institute, RAS, 194021 St Petersburg (Russian Federation); Galkin, N G [Ioffe Physico-Technical Institute, RAS, 194021 St Petersburg (Russian Federation); Gehlhoff, W [Institut fuer Festkoerperphysik, TU Berlin, D-10623 Berlin (Germany); Klyachkin, L E [Ioffe Physico-Technical Institute, RAS, 194021 St Petersburg (Russian Federation); Malyarenko, A M [Ioffe Physico-Technical Institute, RAS, 194021 St Petersburg (Russian Federation); Shelykh, I A [Physics and Astronomy School, University of Southampton, Highfield, Southampton, S017 1BJ (United Kingdom)

    2006-11-15

    We present the first findings of the spin transistor effect in a Rashba gate-controlled ring embedded in a p-type self-assembled silicon quantum well that is prepared on an n-type Si(100) surface. The coherence and phase sensitivity of the spin-dependent transport of holes are studied by varying the values of the external magnetic field and the bias voltage that are applied perpendicularly to the plane of the double-slit ring. First, the amplitude and phase sensitivity of the 0.7 x (2e{sup 2}/h) feature of the hole quantum conductance staircase revealed by the quantum point contact inserted in one of the arms of the double-slit ring are found to result from the interplay of the spontaneous spin polarization and the Rashba spin-orbit interaction. Second, the quantum scatterers connected to two one-dimensional leads and the quantum point contact inserted are shown to define the amplitude and the phase of the Aharonov-Bohm and the Aharonov-Casher conductance oscillations. (letter to the editor)

  1. Phonons in a one-dimensional microfluidic crystal

    CERN Document Server

    Beatus, Tsevi; Bar-Ziv, Roy; 10.1038/nphys432

    2010-01-01

    The development of a general theoretical framework for describing the behaviour of a crystal driven far from equilibrium has proved difficult1. Microfluidic crystals, formed by the introduction of droplets of immiscible fluid into a liquid-filled channel, provide a convenient means to explore and develop models to describe non-equilibrium dynamics2, 3, 4, 5, 6, 7, 8, 9, 10, 11. Owing to the fact that these systems operate at low Reynolds number (Re), in which viscous dissipation of energy dominates inertial effects, vibrations are expected to be over-damped and contribute little to their dynamics12, 13, 14. Against such expectations, we report the emergence of collective normal vibrational modes (equivalent to acoustic 'phonons') in a one-dimensional microfluidic crystal of water-in-oil droplets at Reapprox10-4. These phonons propagate at an ultra-low sound velocity of approx100 mum s-1 and frequencies of a few hertz, exhibit unusual dispersion relations markedly different to those of harmonic crystals, and g...

  2. Charge transport through one-dimensional Moiré crystals.

    Science.gov (United States)

    Bonnet, Roméo; Lherbier, Aurélien; Barraud, Clément; Della Rocca, Maria Luisa; Lafarge, Philippe; Charlier, Jean-Christophe

    2016-01-20

    Moiré superlattices were generated in two-dimensional (2D) van der Waals heterostructures and have revealed intriguing electronic structures. The appearance of mini-Dirac cones within the conduction and valence bands of graphene is one of the most striking among the new quantum features. A Moiré superstructure emerges when at least two periodic sub-structures superimpose. 2D Moiré patterns have been particularly investigated in stacked hexagonal 2D atomic lattices like twisted graphene layers and graphene deposited on hexagonal boron-nitride. In this letter, we report both experimentally and theoretically evidence of superlattices physics in transport properties of one-dimensional (1D) Moiré crystals. Rolling-up few layers of graphene to form a multiwall carbon nanotube adds boundaries conditions that can be translated into interference fringes-like Moiré patterns along the circumference of the cylinder. Such a 1D Moiré crystal exhibits a complex 1D multiple bands structure with clear and robust interband quantum transitions due to the presence of mini-Dirac points and pseudo-gaps. Our devices consist in a very large diameter (>80 nm) multiwall carbon nanotubes of high quality, electrically connected by metallic electrodes acting as charge reservoirs. Conductance measurements reveal the presence of van Hove singularities assigned to 1D Moiré superlattice effect and illustrated by electronic structure calculations.

  3. Redshift distortions in one-dimensional power spectra

    CERN Document Server

    Desjacques, V; Desjacques, Vincent; Nusser, Adi

    2004-01-01

    We present a model for one-dimensional (1D) matter power spectra in redshift space as estimated from data provided along individual lines of sight. We derive analytic expressions for these power spectra in the linear and nonlinear regimes, focusing on redshift distortions arising from peculiar velocities. In the linear regime, redshift distortions enhance the 1D power spectra only on small scales, and do not affect the power on large scales. This is in contrast to the effect of distortions on three-dimensional (3D) power spectra estimated from data in 3D space, where the enhancement is independent of scale. For CDM cosmologies, the 1D power spectra in redshift and real space are similar for wavenumbers $q<0.1h/Mpc$ where both have a spectral index close to unity, independent of the details of the 3D power spectrum. Nonlinear corrections drive the 1D power spectrum in redshift space into a nearly universal shape over scale $q<10h/Mpc$, and suppress the power on small scales as a result of the strong velo...

  4. One dimensional numerical simulation of small scale CFB combustors

    Energy Technology Data Exchange (ETDEWEB)

    Gungor, Afsin [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Nigde University, 51100 Nigde (Turkey)

    2009-03-15

    In this study, a one-dimensional model which includes volatilization, attrition and combustion of char particles for a circulating fluidized bed (CFB) combustor has been developed. In the modeling, the CFB combustor is analyzed in two regions: bottom zone considering as a bubbling fluidized bed in turbulent fluidization regime and upper zone core-annulus solids flow structure is established. In the bottom zone, a single-phase back-flow cell model is used to represent the solid mixing. Solids exchange, between the bubble phase and emulsion phase is a function of the bubble diameter and varies along the axis of the combustor. In the upper zone, particles move upward in the core and downward in the annulus. Thickness of the annulus varies according to the combustor height. Using the developed simulation program, the effects of operational parameters which are the particle diameter, superficial velocity and air-to-fuel ratio on net solids flux, oxygen and carbon dioxide mole ratios along the bed height and carbon content and bed temperature on the top of the riser are investigated. Simulation results are compared with test results obtained from the 50 kW Gazi University Heat Power Laboratory pilot scale unit and good agreement is observed. (author)

  5. Immobilization and One-Dimensional Arrangement of Virus Capsids with Nanoscale Precision Using DNA Origami

    Energy Technology Data Exchange (ETDEWEB)

    Stephanopoulos, Nicholas [Univ. of California, Berkeley, CA (United States); Liu, Minghui [Arizona State Univ., Tempe, AZ (United States); Tong, Gary J [Univ. of California, Berkeley, CA (United States); Li, Zhe [Arizona State Univ., Tempe, AZ (United States); Liu, Yan [Arizona State Univ., Tempe, AZ (United States); Yan, Hao [Arizona State Univ., Tempe, AZ (United States); Francis, Matthew B [Univ. of California, Berkeley, CA (United States)

    2010-06-24

    DNA origami was used as a scaffold to arrange spherical virus capsids into one-dimensional arrays with precise nanoscale positioning. To do this, we first modified the interior surface of bacteriophage MS2 capsids with fluorescent dyes as a model cargo. An unnatural amino acid on the external surface was then coupled to DNA strands that were complementary to those extending from origami tiles. Two different geometries of DNA tiles (rectangular and triangular) were used. The capsids associated with tiles of both geometries with virtually 100% efficiency under mild annealing conditions, and the location of capsid immobilization on the tile could be controlled by the position of the probe strands. The rectangular tiles and capsids could then be arranged into one-dimensional arrays by adding DNA strands linking the corners of the tiles. The resulting structures consisted of multiple capsids with even spacing (~100 nm). We also used a second set of tiles that had probe strands at both ends, resulting in a one-dimensional array of alternating capsids and tiles. This hierarchical self-assembly allows us to position the virus particles with unprecedented control and allows the future construction of integrated multicomponent systems from biological scaffolds using the power of rationally engineered DNA nanostructures.

  6. Hydrogen Gas Sensors Based on Semiconductor Oxide Nanostructures

    Directory of Open Access Journals (Sweden)

    Yongming Hu

    2012-04-01

    Full Text Available Recently, the hydrogen gas sensing properties of semiconductor oxide (SMO nanostructures have been widely investigated. In this article, we provide a comprehensive review of the research progress in the last five years concerning hydrogen gas sensors based on SMO thin film and one-dimensional (1D nanostructures. The hydrogen sensing mechanism of SMO nanostructures and some critical issues are discussed. Doping, noble metal-decoration, heterojunctions and size reduction have been investigated and proved to be effective methods for improving the sensing performance of SMO thin films and 1D nanostructures. The effect on the hydrogen response of SMO thin films and 1D nanostructures of grain boundary and crystal orientation, as well as the sensor architecture, including electrode size and nanojunctions have also been studied. Finally, we also discuss some challenges for the future applications of SMO nanostructured hydrogen sensors.

  7. One dimensional speckle fields generated by three phase level diffusers

    Science.gov (United States)

    Cabezas, L.; Amaya, D.; Bolognini, N.; Lencina, A.

    2015-02-01

    Speckle patterns have usually been obtained by using ground glass as random diffusers. Liquid-crystal spatial light modulators have opened the possibility of engineering tailored speckle fields obtained from designed diffusers. In this work, one-dimensional Gaussian speckle fields with fully controllable features are generated. By employing a low-cost liquid-crystal spatial light modulator, one-dimensional three phase level diffusers are implemented. These diffusers make it possible to control average intensity distribution and statistical independence among the generated patterns. The average speckle size is governed by an external slit pupil. A theoretical model to describe the generated speckle patterns is developed. Experimental and theoretical results confirming the generation of one-dimensional speckle fields are presented. Some possible applications of these speckles, such as atom trapping and super-resolution imaging, are briefly envisaged.

  8. Analysis of one dimensional and two dimensional fuzzy controllers

    Institute of Scientific and Technical Information of China (English)

    Ban Xiaojun; Gao Xiaozhi; Huang Xianlin; Wu Tianbao

    2006-01-01

    The analytical structures and the corresponding mathematical properties of the one dimensional and two dimensional fuzzy controllers are first investigated in detail.The nature of these two kinds of fuzzy controllers is next probed from the perspective of control engineering. For the one dimensional fuzzy controller, it is concluded that this controller is a combination of a saturation element and a nonlinear proportional controller, and the system that employs the one dimensional fuzzy controller is the combination of an open-loop control system and a closedloop control system. For the latter case, it is concluded that it is a hybrid controller, which comprises the saturation part, zero-output part, nonlinear derivative part, nonlinear proportional part, as well as nonlinear proportional-derivative part, and the two dimensional fuzzy controller-based control system is a loop-varying system with varying number of control loops.

  9. Engineering nanostructural routes for enhancing thermoelectric performance: bulk to nanoscale

    Directory of Open Access Journals (Sweden)

    Rajeshkumar eMohanraman

    2015-11-01

    Full Text Available Thermoelectricity is a very important physical property, especially its significance in heat-electricity conversion. If thermoelectric devices can be effectively applied to the recovery of the renewable energies, such as waste heat and solar energy, the energy shortage and global warming issues may be greatly relieved. This review focusses recent developments on the thermoelectric performance of a low-dimensional material, bulk nanostructured materials, conventional bulk materials etc. Particular emphasis is given on, how the nanostructure in nanostructured composites, confinement effects in one-dimensional nanowires and doping effects in conventional bulk composites plays an important role in ZT enhancement.

  10. Branching solutions to one-dimensional variational problems

    CERN Document Server

    Ivanov, A O

    2001-01-01

    This book deals with the new class of one-dimensional variational problems - the problems with branching solutions. Instead of extreme curves (mappings of a segment to a manifold) we investigate extreme networks, which are mappings of graphs (one-dimensional cell complexes) to a manifold. Various applications of the approach are presented, such as several generalizations of the famous Steiner problem of finding the shortest network spanning given points of the plane. Contents: Preliminary Results; Networks Extremality Criteria; Linear Networks in R N; Extremals of Length Type Functionals: The

  11. Rashba electron transport in one-dimensional quantum waveguides

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The properties of Rashba wave function in the planar one-dimensional waveguide are studied, and the following results are obtained. Due to the Rashba effect, the plane waves of electron with the energy E divide into two kinds of waves with the wave vectors k 1 =k 0 +k δ and k 2 =k 0 -k δ , where k δ is proportional to the Rashba coefficient, and their spin orientations are +π/2 (spin up) and -π/2 (spin down) with respect to the circuit, respectively. If there is gate or ferromagnetic contact in the circuit, the Rashba wave function becomes standing wave form exp(±ik δ l)sin[k 0 (l-L)], where L is the position coordinate of the gate or contact. Unlike the electron without considering the spin, the phase of the Rashba plane or standing wave function depends on the direction angle θ of the circuit. The travel velocity of the Rashba waves with the wave vector k 1 or k 2 are the same hk0/m * . The boundary conditions of the Rashba wave functions at the intersection of circuits are given from the continuity of wave functions and the conservation of current density. Using the boundary conditions of Rashba wave functions we study the transmission and reflection probabilities of Rashba electron moving in several structures, and find the interference effects of the two Rashba waves with different wave vectors caused by ferromagnetic contact or the gate. Lastly we derive the general theory of multiple branches structure. The theory can be used to design various spin polarized devices.

  12. Symmetricity of Distribution for One-Dimensional Hadamard Walk

    CERN Document Server

    Konno, N; Soshi, T; Konno, Norio; Namiki, Takao; Soshi, Takahiro

    2002-01-01

    In this paper we study a one-dimensional quantum random walk with the Hadamard transformation which is often called the Hadamard walk. We construct the Hadamard walk using a transition matrix on probability amplitude and give some results on symmetricity of probability distributions for the Hadamard walk.

  13. The electromagnetic Brillouin precursor in one-dimensional photonic crystals

    NARCIS (Netherlands)

    Uitham, R.; Hoenders, B. J.

    2008-01-01

    We have calculated the electromagnetic Brillouin precursor that arises in a one-dimensional photonic crystal that consists of two homogeneous slabs which each have a single electron resonance. This forerunner is compared with the Brillouin precursor that arises in a homogeneous double-electron reson

  14. Time correlation functions for the one-dimensional Lorentz gas

    NARCIS (Netherlands)

    Mazo, R.M.; Beijeren, H. van

    1983-01-01

    The velocity autocorrelation function and related quantities are investigated for the one-dimensional deterministic Lorentz gas, consisting of randomly distributed fixed scatterers and light particles moving back and forth between two of these at a constant given speed. An expansion for the velocity

  15. Current-Voltage Characteristics of Quasi-One-Dimensional Superconductors

    DEFF Research Database (Denmark)

    Vodolazov, D.Y.; Peeters, F.M.; Piraux, L.

    2003-01-01

    The current-voltage (I-V) characteristics of quasi-one-dimensional superconductors were discussed. The I-V characteristics exhibited an unusual S behavior. The dynamics of superconducting condensate and the existence of two different critical currents resulted in such an unusual behavior....

  16. The Long Decay Model of One-Dimensional Projectile Motion

    Science.gov (United States)

    Lattery, Mark Joseph

    2008-01-01

    This article introduces a research study on student model formation and development in introductory mechanics. As a point of entry, I present a detailed analysis of the Long Decay Model of one-dimensional projectile motion. This model has been articulated by Galileo ("in De Motu") and by contemporary students. Implications for instruction are…

  17. The electromagnetic Brillouin precursor in one-dimensional photonic crystals

    NARCIS (Netherlands)

    Uitham, R.; Hoenders, B. J.

    2008-01-01

    We have calculated the electromagnetic Brillouin precursor that arises in a one-dimensional photonic crystal that consists of two homogeneous slabs which each have a single electron resonance. This forerunner is compared with the Brillouin precursor that arises in a homogeneous double-electron

  18. One-dimensional Bose gas on an atom chip

    NARCIS (Netherlands)

    van Amerongen, A.H.

    2008-01-01

    We describe experiments investigating the (coherence) properties of a finite-temperature one-dimensional (1D) Bose gas with repulsive interactions. The confining magnetic field is generated with a micro-electronic circuit. This microtrap for atoms or `atom chip' is particularly suited to generate a

  19. One-dimensional models of thermal activation under shear stress

    CSIR Research Space (South Africa)

    Nabarro, FRN

    2003-01-01

    Full Text Available The analysis of thermal activation under shear stress in three- and even two-dimensional models presents unresolved problems. The analysis of one-dimensional models presented here may illuminate the study of more realistic models. For the model...

  20. How good are one-dimensional Josephson junction models?

    DEFF Research Database (Denmark)

    Lomdahl, P. S.; Olsen, O.H.; Eilbeck, J. C.

    1985-01-01

    A two-dimensional model of Josephson junctions of overlap type is presented and shown to reduce to the usual one-dimensional (1D) model in the limit of a very narrow junction. Comparisons between the stability limits for fluxon reflection obtained from the two models suggest that the many results...

  1. Quasi-one-dimensional intermittent flux behavior in superconducting films

    DEFF Research Database (Denmark)

    Qviller, A. J.; Yurchenko, V. V.; Galperin, Y. M.

    2012-01-01

    . The intermittent behavior shows no threshold value in the applied field, in contrast to conventional flux jumping. The results strongly suggest that the quasi-one-dimensional flux jumps are of a different nature than the thermomagnetic dendritic (branching) avalanches that are commonly found in superconducting...

  2. Radiative decay of the one-dimensional large acoustic polaron

    Energy Technology Data Exchange (ETDEWEB)

    Ivic, Zoran; Zekovic, Slobodan; Przulj, Zeljko

    2002-12-30

    Finite temperature dynamics and stability of the adiabatic large acoustic polaron in one-dimensional systems have been examined by means of the perturbation method based upon the inverse scattering transform. Polaron life-time was estimated in dependence of temperature and electron (exciton)-phonon coupling constant.

  3. An algebraic study of unitary one dimensional quantum cellular automata

    CERN Document Server

    Arrighi, P

    2005-01-01

    We provide algebraic characterizations of unitary one dimensional quantum cellular automata. We do so both by algebraizing existing decision procedures, and by adding constraints into the model which do not change the quantum cellular automata's computational power. The configurations we consider have finite but unbounded size.

  4. Novel Progress in One-Dimensional Carbon Nanotubes Studies

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ One-dimensional carbon nanotubes (CNT) have received considerable attention from researchers worldwide. It is not only because of their unique physical properties, but also their potential applications. Recently, researchers of the CAS Institute of Physics have made new progress in the field.

  5. Bloch oscillations in an aperiodic one-dimensional potential

    NARCIS (Netherlands)

    de Moura, FABF; Lyra, ML; Dominguez-Adame, F; Malyshev, V.A.

    2005-01-01

    We study the dynamics of an electron subjected to a static uniform electric field within a one-dimensional tight-binding model with a slowly varying aperiodic potential. The unbiased model is known to support phases of localized and extended one-electron states separated by two mobility edges. We sh

  6. Lie symmetry algebra of one-dimensional nonconservative dynamical systems

    Institute of Scientific and Technical Information of China (English)

    Liu Cui-Mei; Wu Run-Heng; Fu Jing-Li

    2007-01-01

    Lie symmetry algebra of linear nonconservative dynamical systems is studied in this paper. By using 1-1 mapping,the Lie point and Lie contact symmetry algebras are obtained from two independent solutions of the one-dimensional linear equations of motion.

  7. Intertwining technique for the one-dimensional stationary Dirac equation

    CERN Document Server

    Nieto, L M; Samsonov, B F; Samsonov, Boris F.

    2003-01-01

    The technique of differential intertwining operators (or Darboux transformation operators) is systematically applied to the one-dimensional Dirac equation. The following aspects are investigated: factorization of a polynomial of Dirac Hamiltonians, quadratic supersymmetry, closed extension of transformation operators, chains of transformations, and finally particular cases of pseudoscalar and scalar potentials. The method is widely illustrated by numerous examples.

  8. One Dimensional Quasi-Exactly Solvable Differential Equations

    OpenAIRE

    Fasihi, Mohammad A.

    2006-01-01

    In this paper by means of similarity transformation we find some one-dimensional quasi-exactly solvable differential equations and their related Hamiltonians which appear in physical problems. We have provided also two examples with application of these differential equations.

  9. Exact results for one dimensional fluids through functional integration

    CERN Document Server

    Fantoni, Riccardo

    2016-01-01

    We review some of the exactly solvable one dimensional continuum fluid models of equilibrium classical statistical mechanics under the unified setting of functional integration in one dimension. We make some further developments and remarks concerning fluids with penetrable particles. We then apply our developments to the study of the Gaussian core model for which we are unable to find a well defined thermodynamics.

  10. Transport through a Finite One-Dimensional Crystal

    NARCIS (Netherlands)

    Kouwenhoven, L.P.; Hekking, F.W.J.; Wees, B.J. van; Harmans, C.J.P.M.; Timmering, C.E.; Foxon, C.T.

    1990-01-01

    We have studied the magnetotransport properties of an artificial one-dimensional crystal. The crystal consists of a sequence of fifteen quantum dots, defined in the two-dimensional electron gas of a GaAs/AlGaAs heterostructure by means of a split-gate technique. At a fixed magnetic field of 2 T, two

  11. Optical enhancement effects of plasmonic nanostructures on organic photovoltaic cells

    KAUST Repository

    Park, Hui Joon

    2015-04-01

    © 2015 Hui Joon Park and L. Jay Guo. Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. All rights reserved. In this article, the optical enhancement effects of plasmonic nanostructures on OPV cells were reviewed as an effective way to resolve the mismatch problems between the short exciton diffusion length in organic semiconductors (around 10 nm) and the large thickness required to fully absorb sunlight (e.g. hundreds of nanometers). Especially, the performances of OPVs with plasmonic nanoparticles in photoactive and buffer layers and with periodic nanostructures were investigated. Furthermore, nanoimprint lithography-based nanofabrication processes that can easily control the dimension and uniformity of structures for large-area and uniform plasmonic nanostructures were demonstrated.

  12. Barnett effect in thin magnetic films and nanostructures

    NARCIS (Netherlands)

    Bretzel, S.; Bauer, G.E.W.; Tserkovnyak, Y.; Brataas, A.

    2009-01-01

    The Barnett effect refers to the magnetization induced by rotation of a demagnetized ferromagnet. We describe the location and stability of stationary states in rotating nanostructures using the Landau–Lifshitz–Gilbert equation. The conditions for an experimental observation of the Barnett effect in

  13. Spatial modes in one-dimensional models for capillary jets

    Science.gov (United States)

    Guerrero, J.; González, H.; García, F. J.

    2016-03-01

    One-dimensional (1D) models are widely employed to simplify the analysis of axisymmetric capillary jets. These models postulate that, for slender deformations of the free surface, the radial profile of the axial velocity can be approximated as uniform (viscous slice, averaged, and Cosserat models) or parabolic (parabolic model). In classical works on spatial stability analysis with 1D models, considerable misinterpretation was generated about the modes yielded by each model. The already existing physical analysis of three-dimensional (3D) axisymmetric spatial modes enables us to relate these 1D spatial modes to the exact 3D counterparts. To do so, we address the surface stimulation problem, which can be treated as linear, by considering the effect of normal and tangential stresses to perturb the jet. A Green's function for a spatially local stimulation having a harmonic time dependence provides the general formalism to describe any time-periodic stimulation. The Green's function of this signaling problem is known to be a superposition of the spatial modes, but in fact these modes are of fundamental nature, i.e., not restricted to the surface stimulation problem. The smallness of the wave number associated with each mode is the criterion to validate or invalidate the 1D approaches. The proposed axial-velocity profiles (planar or parabolic) also have a remarkable influence on the outcomes of each 1D model. We also compare with the classical 3D results for (i) conditions for absolute instability, and (ii) the amplitude of the unstable mode resulting from both normal and tangential surface stress stimulation. Incidentally, as a previous task, we need to re-deduce 1D models in order to include eventual stresses of various possible origins (electrohydrodynamic, thermocapillary, etc.) applied on the free surface, which were not considered in the previous general formulations.

  14. Hardening transition in a one-dimensional model for ferrogels

    Science.gov (United States)

    Annunziata, Mario Alberto; Menzel, Andreas M.; Löwen, Hartmut

    2013-05-01

    We introduce and investigate a coarse-grained model for quasi one-dimensional ferrogels. In our description the magnetic particles are represented by hard spheres with a magnetic dipole moment in their centers. Harmonic springs connecting these spheres mimic the presence of a cross-linked polymer matrix. A special emphasis is put on the coupling of the dipolar orientations to the elastic deformations of the matrix, where a memory effect of the orientations is included. Although the particles are displaced along one spatial direction only, the system already shows rich behavior: as a function of the magnetic dipole moment, we find a phase transition between "soft-elastic" states with finite interparticle separation and finite compressive elastic modulus on the one hand, and "hardened" states with touching particles and therefore diverging compressive elastic modulus on the other hand. Corresponding phase diagrams are derived neglecting thermal fluctuations of the magnetic particles. In addition, we consider a situation in which a spatially homogeneous magnetization is initially imprinted into the material. Depending on the strength of the magneto-mechanical coupling between the dipole orientations and the elastic deformations, the system then relaxes to a uniaxially ferromagnetic, an antiferromagnetic, or a spiral state of magnetization to minimize its energy. One purpose of our work is to provide a largely analytically solvable approach that can provide a benchmark to test future descriptions of higher complexity. From an applied point of view, our results could be exploited, for example, for the construction of novel damping devices of tunable shock absorbance.

  15. Visualizing One-Dimensional Electronic States and their Scattering in Semi-conducting Nanowires

    Science.gov (United States)

    Beidenkopf, Haim; Reiner, Jonathan; Norris, Andrew; Nayak, Abhay Kumar; Avraham, Nurit; Shtrikman, Hadas

    One-dimensional electronic systems constitute a fascinating playground for the emergence of exotic electronic effects and phases, within and beyond the Tomonaga-Luttinger liquid paradigm. More recently topological superconductivity and Majorana modes were added to that long list of phenomena. We report scanning tunneling microscopy and spectroscopy measurements conducted on pristine, epitaxialy grown InAs nanowires. We resolve the 1D electronic band structure manifested both via Van-Hove singularities in the local density-of-states, as well as by the quasi-particle interference patterns, induced by scattering from surface impurities. By studying the scattering of the one-dimensional electronic states off various scatterers, including crystallographic defects and the nanowire end, we identify new one-dimensional relaxation regimes and yet unexplored effects of interactions. Some of these may bear implications on the topological superconducting state and Majorana modes therein. The authors acknowledge support from the Israeli Science Foundation (ISF).

  16. Correlations in light propagation in one-dimensional waveguides for classical and quantum degenerate atoms

    CERN Document Server

    Ruostekoski, Janne

    2016-01-01

    We study the transmission of light through a one-dimensional waveguide that confines strongly coupled classical or quantum degenerate fermionic atomic ensembles. The emergence of light-induced correlation effects between the atoms is analyzed by using stochastic Monte-Carlo simulations and transfer matrix methods of transport theory. The conditions of the correlated collective response are identified in terms of the atom density, thermal broadening, and photon losses. We also calculate the "cooperative Lamb shift" for the waveguide transmission resonance, and discuss line shifts that are specific to effectively one-dimensional waveguide systems.

  17. Nanostructural Effect of ZnO on Light Extraction Efficiency of Near-Ultraviolet Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Young Jae Park

    2016-01-01

    Full Text Available The effect of ZnO nanostructures on the light output power of 375 nm near-ultraviolet light-emitting diodes (NUV-LEDs was investigated by comparing one-dimensional (1D nanorods (NR-ZnO with two-dimensional (2D nanosheets (NS-ZnO. ZnO nanostructures were grown on a planar indium tin oxide (ITO by solution based method at low temperature of 90°C without degradation of the forward voltage. At an injection current of 100 mA, the light output efficiency of NUV-LED with NR-ZnO was enhanced by around 30% compared to the conventional NUV-LEDs without ZnO nanostructures. This improvement is due to the formation of a surface texturing, resulting in a larger escape cone and a multiple scattering for the photons in the NUV-LED, whereas the light output efficiency of NUV-LED with NS-ZnO was lower than that of the conventional NUV-LEDs due to the internal reflection and light absorption in the defective sites of NS-ZnO.

  18. Inverse design of nanostructured surfaces for color effects

    DEFF Research Database (Denmark)

    Andkjær, Jacob Anders; Johansen, Villads Egede; Friis, Kasper Storgaard;

    2014-01-01

    We propose an inverse design methodology for systematic design of nanostructured surfaces for color effects. The methodology is based on a 2D topology optimization formulation based on frequency-domain finite element simulations for E and/or H polarized waves. The goal of the optimization...... is to maximize color intensity in prescribed direction(s) for a prescribed color (RGB) vector. Results indicate that nanostructured surfaces with any desirable color vector can be generated; that complex structures can generate more intense colors than simple layerings; that angle independent colorings can...

  19. Scalable nanostructuring on polymer by a SiC stamp: optical and wetting effects

    DEFF Research Database (Denmark)

    Argyraki, Aikaterini; Lu, Weifang; Petersen, Paul Michael;

    2015-01-01

    surface. The reflectance of SiC can be reduced down to 0.5% when the ~600nm nanostructures are applied on the surface (bare surface reflectance 25%). The texture of the green SiC color is changed when the different nanostructures are apparent. The ~600nm SiC nanostructures are replicated on polymer...... from 68 (bare) to 123 (nanostructured) degrees. The optical effect on the polymer surface can be maximized by applying a thin aluminum (Al) layer coating on the nanostructures (bare polymer reflectance 11%, nanostructured polymer reflectance 5%, Al coated nanostructured polymer reflectance 3......A method for fabricating scalable antireflective nanostructures on polymer surfaces (polycarbonate) is demonstrated. The transition from small scale fabrication of nanostructures to a scalable replication technique can be quite challenging. In this work, an area per print corresponding to a 2-inch...

  20. Comparison of the elastic coefficients and Calculation Models of the Mechanical Behavior one- Dimensional Composites

    Directory of Open Access Journals (Sweden)

    Saleh Alsubari

    2011-09-01

    Full Text Available In this paper, we present the mechanical models that are devoted to the elastic properties of one-dimensional composite. We have compared the equivalent coefficients of one-dimensional composite, resulting from different models. The validation of the results was made through effective experiments on a one-dimensional composite consisting of fibers of alumina and a matrix of aluminum. This study allows us to better assess the rigidity of composite structures, and the results of calculation of the mechanical behavior, resulting from each model. It appears that the finite element model is the best suited to the approach of a refined conception. For more insurance, we have chosen to make our calculations by finite element in the three-dimensional case, using the technique of homogenization by asymptotic development.

  1. Robust unidirectional transport in a one-dimensional metacrystal with long-range hopping

    CERN Document Server

    Longhi, Stefano

    2016-01-01

    In two- and three-dimensional structures, topologically-protected chiral edge modes offer a powerful mean to realize robust light transport. However, little attention has been paid so far to robust one-way transport in one-dimensional systems. Here it is shown that unidirectional transport, which is immune to disorder and backscattering, can occur in certain one-dimensional metacrystals with long-range hopping without resorting to topological protection. Such metacrystals are described by an effective Hermitian Hamiltonian with broken time reversal symmetry, and transport does not require adiabatic (Thouless) pumping. A simple implementation in optics of such one-dimensional metacrystals, based on transverse light dynamics in a self-imaging optical cavity with phase gratings, is suggested

  2. Strong correlations and topological order in one-dimensional systems

    Science.gov (United States)

    De Gottardi, Wade Wells

    This thesis presents theoretical studies of strongly correlated systems as well as topologically ordered systems in 1D. Non-Fermi liquid behavior characteristic of interacting 1D electron systems is investigated with an emphasis on experimentally relevant setups and observables. The existence of end Majorana fermions in a 1D p-wave superconductor subject to periodic, incommensurate and disordered potentials is studied. The Tomonaga-Luttinger liquid (TLL), a model of interacting electrons in one spatial dimension, is considered in the context of two systems of experimental interest. First, a study of the electronic properties of single-walled armchair carbon nanotubes in the presence of transverse electric and magnetic fields is presented. As a result of their effect on the band structure and electron wave functions, fields alter the nature of the (effective) Coulomb interaction in tubes. In particular, it is found that fields couple to nanotube bands (or valleys), a quantum degree of freedom inherited from the underlying graphene lattice. As revealed by a detailed TLL calculation, it is predicted that fields induce electrons to disperse into their spin, band, and charge components. Fields also provide a means of tuning the shell-filling behavior associated with short tubes. The phenomenon of charge fractionalization is investigated in a one-dimensional ring. TLL theory predicts that momentum-resolved electrons injected into the ring will fractionalize into clockwise- and counterclockwise-moving quasiparticles. As a complement to transport measurements in quantum wires connected to leads, non-invasive measures involving the magnetic field profiles around the ring are proposed. Topological aspects of 1D p-wave superconductors are explored. The intimate connection between non-trivial topology (fermions) and spontaneous symmetry breaking (spins) in one-dimension is investigated. Building on this connection, a spin ladder system endowed with vortex degrees of freedom is

  3. True Bilayer Exciton Condensate of One-Dimensional Electrons

    Science.gov (United States)

    Kantian, A.; Abergel, D. S. L.

    2017-07-01

    We theoretically predict that a true bilayer exciton condensate, characterized by off-diagonal long-range order and global phase coherence, can be created in one-dimensional solid state electron systems. The mechanism by which this happens is to introduce a single particle hybridization of electron and hole populations, which locks the phase of the relevant mode and hence invalidates the Mermin-Wagner theorem. Electron-hole interactions then amplify this tendency towards off-diagonal long-range order, enhancing the condensate properties by more than an order of magnitude over the noninteracting limit. We show that the temperatures below which a substantial condensate fraction would form could reach hundreds of Kelvin, a benefit of the weak screening in one-dimensional systems.

  4. Resonance Raman spectroscopy in one-dimensional carbon materials

    Directory of Open Access Journals (Sweden)

    Dresselhaus Mildred S.

    2006-01-01

    Full Text Available Brazil has played an important role in the development and use of resonance Raman spectroscopy as a powerful characterization tool for materials science. Here we present a short history of Raman scattering research in Brazil, highlighting the important contributions to the field coming from Brazilian researchers in the past. Next we discuss recent and important contributions where Brazil has become a worldwide leader, that is on the physics of quasi-one dimensional carbon nanotubes. We conclude this article by presenting results from a very recent resonance Raman study of exciting new materials, that are strictly one-dimensional carbon chains formed by the heat treatment of very pure double-wall carbon nanotube samples.

  5. One-dimensional XY model: Ergodic properties and hydrodynamic limit

    Science.gov (United States)

    Shuhov, A. G.; Suhov, Yu. M.

    1986-11-01

    We prove theorems on convergence to a stationary state in the course of time for the one-dimensional XY model and its generalizations. The key point is the well-known Jordan-Wigner transformation, which maps the XY dynamics onto a group of Bogoliubov transformations on the CAR C *-algebra over Z 1. The role of stationary states for Bogoliubov transformations is played by quasifree states and for the XY model by their inverse images with respect to the Jordan-Wigner transformation. The hydrodynamic limit for the one-dimensional XY model is also considered. By using the Jordan-Wigner transformation one reduces the problem to that of constructing the hydrodynamic limit for the group of Bogoliubov transformations. As a result, we obtain an independent motion of "normal modes," which is described by a hyperbolic linear differential equation of second order. For the XX model this equation reduces to a first-order transfer equation.

  6. One-dimensional Si nanolines in hydrogenated Si(001)

    Science.gov (United States)

    François, Bianco; Köster, Sigrun A.; Owen, James G. H.; Renner, Christoph; Bowler, David R.

    2012-02-01

    We present a detailed study of the structural and electronic properties of a self-assembled silicon nanoline embedded in the H-terminated silicon (001) surface, known as the Haiku stripe. The nanoline is a perfectly straight and defect free endotaxial structure of huge aspect ratio; it can grow micrometre long at a constant width of exactly four Si dimers (1.54 nm). Another remarkable property is its capacity to be exposed to air without suffering any degradation. The nanoline grows independently of any step edges at tunable densities, from isolated nanolines to a dense array of nanolines. In addition to these unique structural characteristics, scanning tunnelling microscopy and density functional theory reveal a one-dimensional state confined along the Haiku core. This nanoline is a promising candidate for the long sought after electronic solid-state one-dimensional model system to explore the fascinating quantum properties emerging in such reduced dimensionality. Phys. Rev. B, 84, 035328 (2011)

  7. Luttinger parameter of quasi-one-dimensional para -H2

    Science.gov (United States)

    Ferré, G.; Gordillo, M. C.; Boronat, J.

    2017-02-01

    We have studied the ground-state properties of para-hydrogen in one dimension and in quasi-one-dimensional configurations using the path-integral ground-state Monte Carlo method. This method produces zero-temperature exact results for a given interaction and geometry. The quasi-one-dimensional setup has been implemented in two forms: the inner channel inside a carbon nanotube coated with H2 and a harmonic confinement of variable strength. Our main result is the dependence of the Luttinger parameter on the density within the stable regime. Going from one dimension to quasi-one dimension, keeping the linear density constant, produces a systematic increase of the Luttinger parameter. This increase is, however, not enough to reach the superfluid regime and the system always remain in the quasicrystal regime, according to Luttinger liquid theory.

  8. Kinetic properties of small one-dimensional Ising magnetic

    Science.gov (United States)

    Udodov, Vladimir; Spirin, Dmitriy; Katanov Khakas State University Team

    2011-03-01

    Within the framework of a generalized Ising model, a one-dimensional magnetic of a finite length with free ends is considered. The correlation length critical exponent ν and kinetic critical exponent z of the magnet is calculated taking into account the next nearest neighbor interactions and the external field. Of special interest are non-equilibrium processes taking place within the critical temperature interval, which are characterized critical exponent y and dynamic critical index z . Due to significant difficulties encountered in the experimental investigations (e.g., measurement of z) , a natural solution to this complex problem would be modeling of those non-eqilibrium processes. This work addresses non-equilibrium processes in one-dimensional magnetics. Using the Monte Carlo method, an equilibrium critical exponent of the correlation length ν and the dynamic critical index z are calculated for a finite-size magnetic.

  9. Dark Matter in a One-dimensional Universe

    CERN Document Server

    Sigismondi, C

    2003-01-01

    A computer code to simulate temporal evolution of overdensities in a one-dimensional Universe is presented for didactic purposes. The formation of large scale structures in this one-dimensional universe can be studied both in matter or radiation dominated eras. Since large scale structures are already observed at z > 7, primordial dark matter overdensities delta_DM which are 90 times larger than the observed barionic delta_B in the cosmic microwave background are required at z~1000. This makes possible non-linear gravitational collapse at redshift z >7 and the formation of the structures. Primordial perturbations delta_B~10^-5 do not leave the linear regime of growth without the aid of dark matter's potential wells. This code is suitable for commercial worksheets like MSExcel, StarOffice, or OpenOffice.

  10. Metal-insulator transition in one-dimensional lattices with chaotic energy sequences

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, R.A. [Laboratorio de Fisica Estadistica, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A (Venezuela)]. E-mail: ripinto@ivic.ve; Rodriguez, M. [Laboratorio de Fisica Estadistica, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A (Venezuela); Gonzalez, J.A. [Laboratorio de Fisica Computacional, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A (Venezuela); Medina, E. [Laboratorio de Fisica Estadistica, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A (Venezuela)

    2005-06-20

    We study electronic transport through a one-dimensional array of sites by using a tight binding Hamiltonian, whose site-energies are drawn from a chaotic sequence. The correlation degree between these energies is controlled by a parameter regulating the dynamic Lyapunov exponent measuring the degree of chaos. We observe the effect of chaotic sequences on the localization length, conductance, conductance distribution and wave function, finding evidence of a metal-insulator transition (MIT) at a critical degree of chaos. The one-dimensional metallic phase is characterized by a Gaussian conductance distribution and exhibits a peculiar non-selfaveraging.

  11. Peak, multi-peak and broadband absorption in graphene-based one-dimensional photonic crystal

    Science.gov (United States)

    Miloua, R.; Kebbab, Z.; Chiker, F.; Khadraoui, M.; Sahraoui, K.; Bouzidi, A.; Medles, M.; Mathieu, C.; Benramdane, N.

    2014-11-01

    We theoretically investigate the possibility of enhancing light absorption in graphene-based one dimensional photonic crystal. We demonstrate that it is possible to achieve total light absorption at technologically important wavelengths using one-dimensional graphene-based photonic crystals. By means of the transfer matrix method, we investigate the effect of refractive indices and layer numbers on the optical response of the structure. We found that it is possible to achieve one peak, multi-peak or broadband, and complete optical absorption. As a result, the proposed photonic structures enable myriad potential applications such as photodetection, shielding and optical sensing.

  12. The Quantum Well of One-Dimensional Photonic Crystals

    Directory of Open Access Journals (Sweden)

    Xiao-Jing Liu

    2015-01-01

    Full Text Available We have studied the transmissivity of one-dimensional photonic crystals quantum well (QW with quantum theory approach. By calculation, we find that there are photon bound states in the QW structure (BA6(BBABBn(AB6, and the numbers of the bound states are equal to n+1. We have found that there are some new features in the QW, which can be used to design optic amplifier, attenuator, and optic filter of multiple channel.

  13. Bose gases in one-dimensional harmonic trap

    Indian Academy of Sciences (India)

    JI-XUAN HOU; JING YANG

    2016-10-01

    Thermodynamic quantities, occupation numbers and their fluctuations of a one-dimensional Bose gas confined by a harmonic potential are studied using different ensemble approaches. Combining number theory methods, a new approach is presented to calculate the occupation numbers of different energy levels in microcanonical ensemble. The visible difference of the ground state occupation number in grand-canonical ensemble and microcanonical ensemble is found to decrease by power law as the number of particles increases.

  14. ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES

    OpenAIRE

    Nikola Stefanović

    2007-01-01

    In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic ...

  15. Few interacting fermions in one-dimensional harmonic trap

    CERN Document Server

    Sowiński, Tomasz; Dutta, Omjyoti; Lewenstein, Maciej

    2013-01-01

    We study spin-1/2 fermions, interacting via a two-body contact potential, in a one-dimensional harmonic trap. Applying exact diagonalization, we investigate the behavior at finite interaction strength, and discuss the role of a ground state degeneracy which occurs for sufficiently strong repulsive interaction. Even low temperature or a completely depolarizing channel may then dramatically influence the system's behavior. We calculate level occupation numbers as signatures of thermalization, and we discuss the mechanisms to break the degeneracy.

  16. Hidden Symmetry from Supersymmetry in One-Dimensional Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Alexander A. Andrianov

    2009-06-01

    Full Text Available When several inequivalent supercharges form a closed superalgebra in Quantum Mechanics it entails the appearance of hidden symmetries of a Super-Hamiltonian. We examine this problem in one-dimensional QM for the case of periodic potentials and potentials with finite number of bound states. After the survey of the results existing in the subject the algebraic and analytic properties of hidden-symmetry differential operators are rigorously elaborated in the Theorems and illuminated by several examples.

  17. Thermal breakage of a discrete one-dimensional string.

    Science.gov (United States)

    Lee, Chiu Fan

    2009-09-01

    We study the thermal breakage of a discrete one-dimensional string, with open and fixed ends, in the heavily damped regime. Basing our analysis on the multidimensional Kramers escape theory, we are able to make analytical predictions on the mean breakage rate and on the breakage propensity with respect to the breakage location on the string. We then support our predictions with numerical simulations.

  18. PT-invariant one-dimensional Coulomb problem

    CERN Document Server

    Sinha, A K; Sinha, Anjana; Roychoudhury, Rajkumar

    2002-01-01

    The one-dimensional Coulomb-like potential with a real coupling constant beta, and a centrifugal-like core of strength G = alpha^2 - {1/4}, viz. V(x) = {alpha^2 - (1/4)}/{(x-ic)^2} + beta/|x-ic|, is discussed in the framework of PT-symmetry. The PT-invariant exactly solvable model so formed, is found to admit a double set of real and discrete energies, numbered by a quasi-parity q = +/- 1.

  19. Impurity modes in the one-dimensional XXZ Heisenberg model

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, J.M. [Departamento de Física, Universidade Federal do Piauí, Campus Ministro Petrônio Portella, 57072-970 Teresina, Piauí (Brazil); Leite, R.V. [Centro de Ciências Exatas e Tecnologia, Curso de Física, Universidade Estadual Vale do Acaraú, Av. Dr. Guarany 317, Campus Cidao, 62040-730 Sobral, Ceará (Brazil); Landim, R.R. [Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil); Costa Filho, R.N., E-mail: rai@fisica.ufc.br [Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil)

    2014-04-01

    A Green's function formalism is used to calculate the energy of impurity modes associated with one and/or two magnetic impurities in the one-dimensional Heisenberg XXZ magnetic chain. The system can be tuned from the Heisenberg to the Ising model varying a parameter λ. A numerical study is performed showing two types of localized modes (s and p). The modes depend on λ and the degeneracy of the acoustic modes is broken.

  20. Universal correlations of one-dimensional electrons at low density

    OpenAIRE

    Göhmann, F.

    2000-01-01

    We summarize results on the asymptotics of the two-particle Green functions of interacting electrons in one dimension. Below a critical value of the chemical potential the Fermi surface vanishes, and the system can no longer be described as a Luttinger liquid. Instead, the non-relativistic Fermi gas with infinite point-like repulsion becomes the universal model for the long-wavelength, low temperature physics of the one-dimensional electrons. This model, which we call the impenetrable electro...

  1. One Dimensional Polymeric Organic Photonic Crystals for DFB Lasers

    Directory of Open Access Journals (Sweden)

    F. Scotognella

    2008-01-01

    Full Text Available We present a very simple method to realize a one-dimensional photonic crystal (1D PC, consisting of a dye-doped polymeric multilayer. Due to the high photonic density of states at the edges of the photonic band-gap (PBG, a surface emitting distributed feedback (DFB laser is obtained with this structure. Furthermore, the incidence angle dependence of the PBG of the polymeric multilayer is reported.

  2. PERIODIC SOLUTIONS IN ONE-DIMENSIONAL COUPLED MAP LATTICES

    Institute of Scientific and Technical Information of China (English)

    郑永爱; 刘曾荣

    2003-01-01

    It is proven that the existence of nonlinear solutions with time period in one-dimensional coupled map lattice with nearest neighbor coupling. This is a class of systemswhose behavior can be regarded as infinite array of coupled oscillators. A method forestimating the critical coupling strength below which these solutions with time period persistis given. For some particular nonlinear solutions with time period, exponential decay inspace is proved.

  3. One-dimensional photonic crystals bound by light

    Science.gov (United States)

    Cui, Liyong; Li, Xiao; Chen, Jun; Cao, Yongyin; Du, Guiqiang; Ng, Jack

    2017-08-01

    Through rigorous simulations, the light scattering induced optical binding of one-dimensional (1D) dielectric photonic crystals is studied. The optical forces corresponding to the pass band, band gap, and band edge are qualitatively different. It is shown that light can induce self-organization of dielectric slabs into stable photonic crystals, with its lower band edge coinciding with the incident light frequency. Incident light at normal and oblique incidence and photonic crystals with parity-time symmetry are also considered.

  4. One-dimensional contact process: duality and renormalization.

    Science.gov (United States)

    Hooyberghs, J; Vanderzande, C

    2001-04-01

    We study the one-dimensional contact process in its quantum version using a recently proposed real-space renormalization technique for stochastic many-particle systems. Exploiting the duality and other properties of the model, we can apply the method for cells with up to 37 sites. After suitable extrapolation, we obtain exponent estimates that are comparable in accuracy with the best known in the literature.

  5. Correlation functions of one-dimensional bosons at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M. [CNRS, ENS Lyon (France). Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Institute, Moscow (Russian Federation)

    2010-12-15

    We consider the low-temperature limit of the long-distance asymptotic behavior of the finite temperature density-density correlation function in the one-dimensional Bose gas derived recently in the algebraic Bethe Ansatz framework. Our results confirm the predictions based on the Luttinger liquid and conformal field theory approaches. We also demonstrate that the amplitudes arising in this asymptotic expansion at low-temperature coincide with the amplitudes associated with the so-called critical form factors. (orig.)

  6. Fast Integration of One-Dimensional Boundary Value Problems

    Science.gov (United States)

    Campos, Rafael G.; Ruiz, Rafael García

    2013-11-01

    Two-point nonlinear boundary value problems (BVPs) in both unbounded and bounded domains are solved in this paper using fast numerical antiderivatives and derivatives of functions of L2(-∞, ∞). This differintegral scheme uses a new algorithm to compute the Fourier transform. As examples we solve a fourth-order two-point boundary value problem (BVP) and compute the shape of the soliton solutions of a one-dimensional generalized Korteweg-de Vries (KdV) equation.

  7. The one-dimensional extended Bose-Hubbard model

    Indian Academy of Sciences (India)

    Ramesh V Pai; Rahul Pandit

    2003-10-01

    We use the finite-size, density-matrix-renormalization-group (DMRG) method to obtain the zero-temperature phase diagram of the one-dimensional, extended Bose-Hubbard model, for mean boson density ρ = 1, in the - plane ( and are respectively, onsite and nearest-neighbour repulsive interactions between bosons). The phase diagram includes superfluid (SF), bosonic-Mott-insulator (MI), and mass-density-wave (MDW) phases. We determine the natures of the quantum phase transitions between these phases.

  8. Statistics of resonances in one-dimensional continuous systems

    Indian Academy of Sciences (India)

    Joshua Feinberg

    2009-09-01

    We study the average density of resonances (DOR) of a disordered one-dimensional continuous open system. The disordered system is semi-infinite, with white-noise random potential, and it is coupled to the external world by a semi-infinite continuous perfect lead. Our main result is an integral representation for the DOR which involves the probability density function of the logarithmic derivative of the wave function at the contact point.

  9. Negative Refraction Angular Characterization in One-Dimensional Photonic Crystals

    OpenAIRE

    Jesus Eduardo Lugo; Rafael Doti; Jocelyn Faubert

    2011-01-01

    BACKGROUND: Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity d...

  10. Topological modes in one-dimensional solids and photonic crystals

    Science.gov (United States)

    Atherton, Timothy J.; Butler, Celia A. M.; Taylor, Melita C.; Hooper, Ian R.; Hibbins, Alastair P.; Sambles, J. Roy; Mathur, Harsh

    2016-03-01

    It is shown theoretically that a one-dimensional crystal with time-reversal and particle-hole symmetries is characterized by a topological invariant that predicts the existence or otherwise of edge states. This is confirmed experimentally through the construction and simulation of a photonic crystal analog in the microwave regime. It is shown that the edge mode couples to modes external to the photonic crystal via a Fano resonance.

  11. Gravitational anomalies and one-dimensional behavior of black holes

    Energy Technology Data Exchange (ETDEWEB)

    Majhi, Bibhas Ranjan, E-mail: bibhas.majhi@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, 781039, Guwahati, Assam (India)

    2015-12-08

    It has been pointed out by Bekenstein and Mayo that the behavior of the black hole’s entropy or information flow is similar to information flow through one-dimensional channel. Here I analyze the same issue with the use of gravitational anomalies. The rate of the entropy change (S{sup .}) and the power (P) of the Hawking emission are calculated from the relevant components of the anomalous stress tensor under the Unruh vacuum condition. I show that the dependence of S{sup .} on the power is S{sup .} ∝P{sup 1/2}, which is identical to that for the information flow in a one-dimensional system. This is established by using the (1+1)-dimensional gravitational anomalies first. Then the fact is further bolstered by considering the (1+3)-dimensional gravitational anomalies. It is found that, in the former case, the proportionality constant is exactly identical to the one-dimensional situation, known as Pendry’s formula, while in the latter situation its value decreases.

  12. Gravitational anomalies and one-dimensional behavior of black holes

    Energy Technology Data Exchange (ETDEWEB)

    Majhi, Bibhas Ranjan [Indian Institute of Technology Guwahati, Department of Physics, Guwahati, Assam (India)

    2015-12-15

    It has been pointed out by Bekenstein and Mayo that the behavior of the black hole's entropy or information flow is similar to information flow through one-dimensional channel. Here I analyze the same issue with the use of gravitational anomalies. The rate of the entropy change (S) and the power (P) of the Hawking emission are calculated from the relevant components of the anomalous stress tensor under the Unruh vacuum condition. I show that the dependence of S on the power is S ∝ P{sup 1/2}, which is identical to that for the information flow in a one-dimensional system. This is established by using the (1+1)-dimensional gravitational anomalies first. Then the fact is further bolstered by considering the (1+3)-dimensional gravitational anomalies. It is found that, in the former case, the proportionality constant is exactly identical to the one-dimensional situation, known as Pendry's formula, while in the latter situation its value decreases. (orig.)

  13. Gravitational anomalies and one dimensional behaviour of black holes

    CERN Document Server

    Majhi, Bibhas Ranjan

    2015-01-01

    It has been pointed out by Bekenstein and Mayo that the behavior of the Black hole's entropy or information flow is similar to that through one-dimensional channel. Here I analyse the same issue with the use of gravitational anomalies. The rate of the entropy change ($\\dot{S}$) and the power ($P$) of the Hawking emission are calculated from the relevant components of the anomalous stress-tensor under the Unruh vacuum condition. I show that the dependence of $\\dot{S}$ on power is $\\dot{S}\\propto P^{1/2}$ which is identical to that for the information flow in one dimensional system. This is established by using the ($1+1$) dimensional gravitational anomalies first. Then the fact is further bolstered by considering the ($1+3$) dimensional gravitational anomalies. It is found that in the former case, the proportionality constant is exactly identical to one dimensional situation, known as Pendry's formula, while in later situation its value decreases.

  14. Plasmonic effects in metal-semiconductor nanostructures

    CERN Document Server

    Toropov, Alexey A

    2015-01-01

    Metal-semiconductor nanostructures represent an important new class of materials employed in designing advanced optoelectronic and nanophotonic devices, such as plasmonic nanolasers, plasmon-enhanced light-emitting diodes and solar cells, plasmonic emitters of single photons, and quantum devices operating in infrared and terahertz domains. The combination of surface plasmon resonances in conducting structures, providing strong concentration of an electromagnetic optical field nearby, with sharp optical resonances in semiconductors, which are highly sensitive to external electromagnetic fields, creates a platform to control light on the nanoscale. The design of the composite metal-semiconductor system imposes the consideration of both the plasmonic resonances in metal and the optical transitions in semiconductors - a key issue being their resonant interaction providing a coupling regime. In this book the reader will find descriptions of electrodynamics of conducting structures, quantum physics of semiconducto...

  15. Characterization for defect modes of one-dimensional photonic crystals containing metamaterials

    Institute of Scientific and Technical Information of China (English)

    Ling Tang; Lei Gao; Jianxing Fang

    2008-01-01

    Transmission studies for one-dimensional photonic crystals(1DPCs)containing single-negative(SNG)materials inserted with multiple defects are presented.The numbers and positions of the defect modes inside zero-phase(zero-φeff)gap are found to be well characterized by effective medium theory.

  16. Numerical simulation of the one-dimensional population dynamics with nonlocal competitive losses and convection

    Science.gov (United States)

    Aleutdinova, V. A.; Borisov, A. V.; Shaparev, V. É.; Shapovalov, A. V.

    2011-09-01

    Numerical solutions of the generalized one-dimensional Fisher-Kolmogorov-Petrovskii-Piskunov equation with nonlocal competitive losses and convection are constructed. The influence function for nonlocal losses is chosen in the form of a Gaussian distribution. The effect of convection on the dynamics of the spatially inhomogeneous distribution of the population density is investigated.

  17. Well-posedness for one-dimensional anisotropic Cahn-Hilliard and Allen-Cahn systems

    Directory of Open Access Journals (Sweden)

    Ahmad Makki

    2015-01-01

    Full Text Available Our aim is to prove the existence and uniqueness of solutions for one-dimensional Cahn-Hilliard and Allen-Cahn type equations based on a modification of the Ginzburg-Landau free energy proposed in [8]. In particular, the free energy contains an additional term called Willmore regularization and takes into account strong anisotropy effects.

  18. Fabrication of one-dimensional organic nanomaterials and their optoelectronic applications.

    Science.gov (United States)

    Yu, Hojeong; Kim, Dong Yeong; Lee, Kyung Jin; Oh, Joon Hak

    2014-02-01

    This paper reviews the recent research and development of one-dimensional (1D) organic nanomaterials synthesized from organic semiconductors or conducting polymers and their applications to optoelectronics. We introduce synthetic methodologies for the fabrication of 1D single-crystalline organic nanomaterials and 1D multi-component organic nanostructures, and discuss their optical and electrical properties. In addition, their versatile applications in optoelectronics are highlighted. The fabrication of highly crystalline organic nanomaterials combined with their integration into nanoelectronic devices is recognized as one of the most promising strategies to enhance charge transport properties and achieve device miniaturization. In the last part of this review, we discuss the challenges and the perspectives of organic nanomaterials for applications in the next generation soft electronics, in terms of fabrication, processing, device integration, and investigation on the fundamental mechanisms governing the charge transport behaviors of these advanced materials.

  19. Fabrication of spinel one-dimensional architectures by single-spinneret electrospinning for energy storage applications.

    Science.gov (United States)

    Peng, Shengjie; Li, Linlin; Hu, Yuxiang; Srinivasan, Madhavi; Cheng, Fangyi; Chen, Jun; Ramakrishna, Seeram

    2015-02-24

    A facile and general method is developed to fabricate one-dimensional (1D) spinel composite oxides with complex architectures by using a facile single-spinneret electrospinning technique. It is found that precursor polymers and heating rates could control the structures of the products, such as 1D solid, nanotube and tube-in-tubes structures. Especially, the tube-in-tube structures have been successfully fabricated for various mixed metal oxide, including CoMn2O4, NiCo2O4, CoFe2O4, NiMn2O4 and ZnMn2O4. Benefiting from the unique structure features, the tube-in-tube hollow nanostructures possess superior electrochemical performances in asymmetric supercapacitors and Li-O2 batteries.

  20. One-pot synthesis of one-dimensional CdTe-cystine nanocomposite for humidity sensing

    Science.gov (United States)

    Lu, Zhisong; Wang, Jing; Xie, Jiale; Li, Chang Ming

    2014-03-01

    Quantum dot (QD)-incorporated one-dimensional (1D) nanocomposites offer great application potential. However, a facile one-step synthesis of the nanocomposites and fabrication of their free-standing film for sensing has not been accomplished. Herein a rod-shaped nanocomposite is one-pot synthesized via an L-cysteine-assisted hydrothermal approach, in which synthesis parameters including L-cysteine amount, temperature and reaction duration are tailored to control the composite nanostructures. CdTe nanocrystals are incorporated into the L-cystine matrices to form the nanorods, which tangle each other to network an intact film structure via a simple drying process. The free-standing CdTe-cystine nanorod film is directly utilized as a humidity sensor. This work provides a one-pot synthesis approach to grow 1D CdTe incorporated nanocomposites, demonstrating their great potential in film sensing applications.

  1. Fullerene-based one-dimensional crystalline nanopolymer formed through topochemical transformation of the parent nanowire

    DEFF Research Database (Denmark)

    Geng, Junfeng; Solov'yov, Ilia; Reid, David G.;

    2010-01-01

    Large-scale practical applications of fullerene (C_60) in nanodevices could be significantly facilitated if the commercially available micrometer-scale raw C_60 powder were further processed into a one-dimensional nanowire-related polymer displaying covalent bonding as molecular interlinks...... and resembling traditional important conjugated polymers. However, there has been little study thus far in this area despite the abundant literature on fullerene. Here we report the preparation and characterization of such a C_60-based polymer nanowire, (-C_60.TMB-)_n, where TMB=1,2,4-trimethylbenzene, which...... displays a well-defined crystalline nanostructure, exceptionally large length-to-width ratio and excellent thermal stability. The material is prepared by first growing the corresponding nanowire through a solution phase of C_60 followed by a topochemical polymerization reaction in the solid state. Gas...

  2. Quasi-one-dimensional density of states in a single quantum ring

    Science.gov (United States)

    Kim, Heedae; Lee, Woojin; Park, Seongho; Kyhm, Kwangseuk; Je, Koochul; Taylor, Robert A.; Nogues, Gilles; Dang, Le Si; Song, Jin Dong

    2017-01-01

    Generally confinement size is considered to determine the dimensionality of nanostructures. While the exciton Bohr radius is used as a criterion to define either weak or strong confinement in optical experiments, the binding energy of confined excitons is difficult to measure experimentally. One alternative is to use the temperature dependence of the radiative recombination time, which has been employed previously in quantum wells and quantum wires. A one-dimensional loop structure is often assumed to model quantum rings, but this approximation ceases to be valid when the rim width becomes comparable to the ring radius. We have evaluated the density of states in a single quantum ring by measuring the temperature dependence of the radiative recombination of excitons, where the photoluminescence decay time as a function of temperature was calibrated by using the low temperature integrated intensity and linewidth. We conclude that the quasi-continuous finely-spaced levels arising from the rotation energy give rise to a quasi-one-dimensional density of states, as long as the confined exciton is allowed to rotate around the opening of the anisotropic ring structure, which has a finite rim width.

  3. Study on one-dimensional consolidation of soil under cyclic loading and with varied compressibility

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Ying-chun; XIE Kang-he

    2005-01-01

    This paper presents a semi-analytical method to solve one dimensional consolidation problem by taking consideration of varied compressibility of soil under cyclic loading. In the method, soil stratum is divided equally into n layers while load and consolidation time are also divided into small parts and time intervals accordingly. The problem of one-dimensional consolidation of soil stratum under cyclic loading can then be dealt with at each time interval as one-dimensional linear consolidation of multi-layered soils under constant loading. The compression or rebounding of each soil layer can be judged by the effective stress of the layer. When the effective stress is larger than that in the last time interval, the soil layer is compressed, and when it is smaller, the soil layer rebounds. Thus, appropriate compressibility can be chosen and the consolidation of the layered system can be analyzed by the available analytical linear consolidation theory. Based on the semi-analytical method, a computer program was developed and the behavior of one-dimensional consolidation of soil with varied compressibility under cyclic loading was investigated, and compared with the available consolidation theory which takes no consideration of varied compressibility of soil under cyclic loading. The results showed that by taking the variable compressibility into account, the rate of consolidation of soil was greater than the one predicted by conventional consolidation theory.

  4. One-dimensional Transport Simulation of Pollutants in Natural Streams

    Directory of Open Access Journals (Sweden)

    Mostafa Ramezani

    2016-10-01

    Full Text Available Rivers are the main sources of freshwater systems which governments need to manage and plan to maintain them as per an acceptable quality. In this research, a numerical scheme was used and implemented in MATLAB to provide a one-dimensional water quality tool. This code then was tested with two datasets of Chattahoochee and Mackinaw rivers. To evaluate the model performance, results and sampled data were checked in terms of conformity by using three metrics: CE, MARE, and RMSE. Results were almost near to observed data and metrics’ values were found satisfactory, showing that the employed numerical approach is an appropriate method for surface water quality planning and management.

  5. One-dimensional hydrodynamic model generating turbulent cascade

    CERN Document Server

    Matsumoto, Takeshi

    2016-01-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analogue (enstrophy) in the inviscid case. With a large-scale forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency and self-similarity in the dynamical system structure.

  6. On Global One-Dimensionality proposal in Quantum General Relativity

    CERN Document Server

    Glinka, L A

    2008-01-01

    Quantum General Relativity, better known as Quantum Gravity with additional epithets, currently is faraway from phenomenology. This mental crisis leads at most to empty hypotheses, but not to realistic physics. However, there exists the way, investigated by Dirac, which is constructive for experimental data predictions in astrophysics, high energy physics, and condensed matter physics. It is Field Theory. This article presents certain proposal for new discussion. General Relativity in 3+1 metric field gauge and its canonical quantization is developed. Reduction of the quantum geometrodynamics to Global One-Dimensional bosonic field theory, its quantization, and some conclusions are presented.

  7. Exactly integrable analogue of a one-dimensional gravitating system

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Bruce N. [Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129 (United States)]. E-mail: b.miller@tcu.edu; Yawn, Kenneth R. [Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129 (United States); Maier, Bill [Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129 (United States)

    2005-10-10

    Exchange symmetry in acceleration partitions the configuration space of an N particle one-dimensional gravitational system (OGS) into N{exclamation_point} equivalent cells. We take advantage of the resulting small angular separation between the forces in neighboring cells to construct a related integrable version of the system that takes the form of a central force problem in N-1 dimensions. The properties of the latter, including the construction of trajectories and possible continuum limits, are developed. Dynamical simulation is employed to compare the two models. For some initial conditions, excellent agreement is observed.

  8. One-dimensional inverse problems of mathematical physics

    CERN Document Server

    Lavrent'ev, M M; Yakhno, V G; Schulenberger, J R

    1986-01-01

    This monograph deals with the inverse problems of determining a variable coefficient and right side for hyperbolic and parabolic equations on the basis of known solutions at fixed points of space for all times. The problems are one-dimensional in nature since the desired coefficient of the equation is a function of only one coordinate, while the desired right side is a function only of time. The authors use methods based on the spectral theory of ordinary differential operators of second order and also methods which make it possible to reduce the investigation of the inverse problems to the in

  9. Solution of One-dimensional Dirac Equation via Poincare Map

    CERN Document Server

    Bahlouli, Hocine; Jellal, Ahmed

    2011-01-01

    We solve the general one-dimensional Dirac equation using a "Poincare Map" approach which avoids any approximation to the spacial derivatives and reduces the problem to a simple recursive relation which is very practical from the numerical implementation point of view. To test the efficiency and rapid convergence of this approach we apply it to a vector coupling Woods--Saxon potential, which is exactly solvable. Comparison with available analytical results is impressive and hence validates the accuracy and efficiency of this method.

  10. Fluctuation dissipation ratio in the one dimensional kinetic Ising model

    OpenAIRE

    Lippiello, E.; Zannetti, M.

    2000-01-01

    The exact relation between the response function $R(t,t^{\\prime})$ and the two time correlation function $C(t,t^{\\prime})$ is derived analytically in the one dimensional kinetic Ising model subjected to a temperature quench. The fluctuation dissipation ratio $X(t,t^{\\prime})$ is found to depend on time through $C(t,t^{\\prime})$ in the time region where scaling $C(t,t^{\\prime}) = f(t/t^{\\prime})$ holds. The crossover from the nontrivial form $X(C(t,t^{\\prime}))$ to $X(t,t^{\\prime}) \\equiv 1$ t...

  11. Enhanced dipolar transport in one-dimensional waveguide arrays

    CERN Document Server

    Cantillano, Camilo; Real, Bastián; Rojas-Rojas, Santiago; Delgado, Aldo; Szameit, Alexander; Vicencio, Rodrigo A

    2016-01-01

    We study the transport properties of fundamental and dipolar (first-excited) modes on one-dimensional coupled waveguide arrays. By modulating an optical beam, we are able to generate fundamental and dipolar modes to study discrete diffraction (single-site excitation) and gaussian beam propagation (multi-site excitation \\& phase gradient). We find that dipolar modes experience a coupling constant more than two times larger than the one for fundamental modes. This implies an enhanced transport of energy for dipoles in a tight-binding lattice. Additionally, we study disordered systems and find that while fundamental modes are already trapped in a weakly disorder array, dipoles still diffract across the lattice.

  12. Impedance of rigid bodies in one-dimensional elastic collisions

    OpenAIRE

    Santos, Janilo; de Oliveira, Bruna P. W.; Nelson,Osman Rosso

    2012-01-01

    In this work we study the problem of one-dimensional elastic collisions of billiard balls, considered as rigid bodies, in a framework very different from the classical one presented in text books. Implementing the notion of impedance matching as a way to understand efficiency of energy transmission in elastic collisions, we find a solution which frames the problem in terms of this conception. We show that the mass of the ball can be seen as a measure of its impedance and verify that the probl...

  13. One-dimensional hydrodynamic model generating a turbulent cascade

    Science.gov (United States)

    Matsumoto, Takeshi; Sakajo, Takashi

    2016-05-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analog (enstrophy) in the inviscid case. With a large-scale random forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency, and self-similarity in the dynamical system structure.

  14. Beam interactions in one-dimensional saturable waveguide arrays

    CERN Document Server

    Stepic, M; Rueter, C E; Shandarov, V; Kip, D; Stepic, Milutin; Smirnov, Eugene; Rueter, Christian E.; Shandarov, Vladimir; Kip, Detlef

    2006-01-01

    The interaction between two parallel beams in one-dimensional discrete saturable systems has been investigated using lithium niobate nonlinear waveguide arrays. When the beams are separated by one channel and in-phase it is possible to observe soliton fusion at low power levels. This new result is confirmed numerically. By increasing the power, soliton-like propagation of weakly-coupled beams occurs. When the beams are out-of-phase the most interesting result is the existence of oscillations which resemble the recently discovered Tamm oscillations.

  15. Waves and instability in a one-dimensional microfluidic array

    CERN Document Server

    Liu, Bin; Feng, Yan

    2012-01-01

    Motion in a one-dimensional (1D) microfluidic array is simulated. Water droplets, dragged by flowing oil, are arranged in a single row, and due to their hydrodynamic interactions spacing between these droplets oscillates with a wave-like motion that is longitudinal or transverse. The simulation yields wave spectra that agree well with experiment. The wave-like motion has an instability which is confirmed to arise from nonlinearities in the interaction potential. The instability's growth is spatially localized. By selecting an appropriate correlation function, the interaction between the longitudinal and transverse waves is described.

  16. Fragmented one dimensional man / El hombre unidimensional fragmentado

    Directory of Open Access Journals (Sweden)

    Juan Antonio Rodríguez del Pino

    2013-10-01

    Full Text Available Paraphrase the title of the famous essay by Herbert Marcuse, since the image has traditionally been generated of man, masculinity, has been one-dimensional. I mean, the man was characterized by traits and behaviors established and entrenched since ancient time, considering all other distinguishing signs as mere deviations from the normative improper. But observe that this undeniable reality, as analyzed various researchers through what has come to be called Men's studies, has proven to be a fallacy difficult to maintain throughout history and today turns into fallacious and ineffective against changes in our current existing corporate models.

  17. Molecular nanostamp based on one-dimensional porphyrin polymers.

    Science.gov (United States)

    Kanaizuka, Katsuhiko; Izumi, Atsushi; Ishizaki, Manabu; Kon, Hiroki; Togashi, Takanari; Miyake, Ryosuke; Ishida, Takao; Tamura, Ryo; Haga, Masa-aki; Moritani, Youji; Sakamoto, Masatomi; Kurihara, Masato

    2013-08-14

    Surface design with unique functional molecules by a convenient one-pot treatment is an attractive project for the creation of smart molecular devices. We have employed a silane coupling reaction of porphyrin derivatives that form one-dimensional polymer wires on substrates. Our simple one-pot treatment of a substrate with porphyrin has successfully achieved the construction of nanoscale bamboo shoot structures. The nanoscale bamboo shoots on the substrates were characterized by atomic force microscopy (AFM), UV-vis spectra, and X-ray diffraction (XRD) measurements. The uneven and rigid nanoscale structure has been used as a stamp for constructing bamboo shoot structures of fullerene.

  18. Dynamical Structure Factors of quasi-one-dimensional antiferromagnets

    Science.gov (United States)

    Hagemans, Rob; Caux, Jean-Sébastien; Maillet, Jean Michel

    2007-03-01

    For a long time it has been impossible to accurately calculate the dynamical structure factors (spin-spin correlators as a function of momentum and energy) of quasi-one-dimensional antiferromagnets. For integrable Heisenberg chains, the recently developed ABACUS method (a first-principles computational approach based on the Bethe Ansatz) now yields highly accurate (over 99% of the sum rule) results for the DSF for finite chains, allowing for a very precise description of neutron-scattering data over the full momentum and energy range. We show remarkable agreement between results obtained with ABACUS and experiment.

  19. ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES

    Directory of Open Access Journals (Sweden)

    Nikola Stefanović

    2007-06-01

    Full Text Available In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic leadership style, leadership theory researchers use two dimensional matrices. The two-dimensional matrices define leadership styles on the basis of different parameters. By using these parameters, one can identify two-dimensional styles.

  20. Longitudinal waves in one dimensional non-uniform waveguides

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Wave approach is used to analyze the longitudinal wave motion in one dimensional non-uniform waveguides.With assumptions of constant wave velocity and no wave conversion,there exist four types of non-uniform rods and corresponding traveling wave solutions are investigated.The obtained results indicate that the kinetic energy is preserved as a constant and the wave amplitude is inversely proportional to square root of the cross-sectional area of the rod.Under certain condition,there exists a cut-off frequ...

  1. Bloch oscillations in a one-dimensional spinor gas.

    Science.gov (United States)

    Gangardt, D M; Kamenev, A

    2009-02-20

    A force applied to a spin-flipped particle in a one-dimensional spinor gas may lead to Bloch oscillations of the particle's position and velocity. The existence of Bloch oscillations crucially depends on the viscous friction force exerted by the rest of the gas on the spin excitation. We evaluate the friction in terms of the quantum fluid parameters. In particular, we show that the friction is absent for integrable cases, such as an SU(2) symmetric gas of bosons or fermions. For small deviations from the exact integrability the friction is very weak, opening the possibility to observe Bloch oscillations.

  2. Black Phosphorus based One-dimensional Photonic Crystals and Microcavities

    CERN Document Server

    Kriegel, I

    2016-01-01

    The latest achievements in the fabrication of black phosphorus thin layers, towards the technological breakthrough of a phosphorene atomically thin layer, are paving the way for a their employment in electronics, optics, and optoelectronics. In this work, we have simulated the optical properties of one-dimensional photonic structures, i.e. photonic crystals and microcavities, in which few-layer black phosphorus is one of the components. The insertion of the 5 nm black phosphorous layers leads to a photonic band gap in the photonic crystals and a cavity mode in the microcavity interesting for light manipulation and emission enhancement.

  3. Fourier's law for quasi-one-dimensional chaotic quantum systems

    Science.gov (United States)

    Seligman, Thomas H.; Weidenmüller, Hans A.

    2011-05-01

    We derive Fourier's law for a completely coherent quasi-one-dimensional chaotic quantum system coupled locally to two heat baths at different temperatures. We solve the master equation to first order in the temperature difference. We show that the heat conductance can be expressed as a thermodynamic equilibrium coefficient taken at some intermediate temperature. We use that expression to show that for temperatures large compared to the mean level spacing of the system, the heat conductance is inversely proportional to the level density and, thus, inversely proportional to the length of the system.

  4. Coherent Backscattering of Light Off One-Dimensional Atomic Strings

    Science.gov (United States)

    Sørensen, H. L.; Béguin, J.-B.; Kluge, K. W.; Iakoupov, I.; Sørensen, A. S.; Müller, J. H.; Polzik, E. S.; Appel, J.

    2016-09-01

    We present the first experimental realization of coherent Bragg scattering off a one-dimensional system—two strings of atoms strongly coupled to a single photonic mode—realized by trapping atoms in the evanescent field of a tapered optical fiber, which also guides the probe light. We report nearly 12% power reflection from strings containing only about 1000 cesium atoms, an enhancement of 2 orders of magnitude compared to reflection from randomly positioned atoms. This result paves the road towards collective strong coupling in 1D atom-photon systems. Our approach also allows for a straightforward fiber connection between several distant 1D atomic crystals.

  5. Multiple nonequilibrium steady states for one-dimensional heat flow.

    Science.gov (United States)

    Zhang, F; Isbister, D J; Evans, D J

    2001-08-01

    A nonequilibrium molecular dynamics model of heat flow in one-dimensional lattices is shown to have multiple steady states for any fixed heat field strength f(e) ranging from zero to a certain positive value. We demonstrate that, depending on the initial conditions, there are at least two possibilities for the system's evolution: (i) formation of a stable traveling wave (soliton), and (ii) chaotic motion throughout the entire simulation. The percentage of the soliton-generating trajectories is zero for small field strength f(e), but increases sharply to unity over a critical region of the parameter f(e).

  6. Nonlocal separable potential in the one-dimensional Dirac equation

    Energy Technology Data Exchange (ETDEWEB)

    Calkin, M.G.; Kiang, D.; Nogami, Y.

    1988-08-01

    The one-dimensional Dirac equation is solved for a separable potential of the form of Lorentz scalar plus vector, (..beta..g+h)v(x)v(x'). Exact analytic solutions are obtained for bound and scattering states for arbitrary v(x). For a particular combination of the values of g and h, degeneracy of the bound state occurs, and total reflection also takes place for a certain incident energy. The limiting case, in which v(x) becomes a delta function, is discussed in detail.

  7. One-Dimensional Metals Conjugated Polymers, Organic Crystals, Carbon Nanotubes

    CERN Document Server

    Roth, Siegmar

    2004-01-01

    Low-dimensional solids are of fundamental interest in materials science due to their anisotropic properties. Written not only for experts in the field, this book explains the important concepts behind their physics and surveys the most interesting one-dimensional systems and discusses their present and emerging applications in molecular scale electronics. The second edition of this successful book has been completely revised to include the remarkable achievements of the last ten years of research and applications. Chemists, polymer and materials scientists as well as students will find this bo

  8. Titanate and titania nanostructures and nanostructure assemblies, and methods of making same

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Stanislaus S.; Mao, Yuanbing

    2016-06-14

    The invention relates to nanomaterial's and assemblies including, a micrometer-scale spherical aggregate comprising: a plurality of one-dimensional nanostructures comprising titanium and oxygen, wherein the one-dimensional nanostructures radiate from a hollow central core thereby forming a spherical aggregate.

  9. Titanate and titania nanostructures and nanostructure assemblies, and methods of making same

    Science.gov (United States)

    Wong, Stanislaus S; Mao, Yuanbing

    2013-05-14

    The invention relates to nanomaterials and assemblies including, a micrometer-scale spherical aggregate comprising: a plurality of one-dimensional nanostructures comprising titanium and oxygen, wherein the one-dimensional nanostructures radiate from a hollow central core thereby forming a spherical aggregate.

  10. Simple Two-Dimensional Corrections for One-Dimensional Pulse Tube Models

    Science.gov (United States)

    Lee, J. M.; Kittel, P.; Timmerhaus, K. D.; Radebaugh, R.

    2004-01-01

    One-dimensional oscillating flow models are very useful for designing pulse tubes. They are simple to use, not computationally intensive, and the physical relationship between temperature, pressure and mass flow are easy to understand when used in conjunction with phasor diagrams. They do not possess, however, the ability to directly calculate thermal and momentum diffusion in the direction transverse to the oscillating flow. To account for transverse effects, lumped parameter corrections, which are obtained though experiment, must be used. Or two-dimensional solutions of the differential fluid equations must be obtained. A linear two-dimensional solution to the fluid equations has been obtained. The solution provides lumped parameter corrections for one-dimensional models. The model accounts for heat transfer and shear flow between the gas and the tube. The complex Nusselt number and complex shear wall are useful in describing these corrections, with phase relations and amplitudes scaled with the Prandtl and Valensi numbers. The calculated ratio, a, between a two-dimensional solution of the oscillating temperature and velocity and a one-dimensional solution for the same shows a scales linearly with Va for Va less than 30. In this region alpha less than 0.5, that is, the enthalpy flow calculated with a two-dimensional model is 50% of a calculation using a one-dimensional model. For Va greater than 250, alpha = 0.8, showing that diffusion is still important even when it is confined to a thing layer near the tube wall.

  11. Quasi-Dirac points in one-dimensional graphene superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.H.; Tseng, P.; Hsueh, W.J., E-mail: hsuehwj@ntu.edu.tw

    2016-08-26

    Quasi-Dirac points (QDPs) with energy different from the traditional Dirac points (TDPs) have been found for the first time in one-dimensional graphene superlattices. The angular-averaged conductance reaches a minimum value at the QDPs, at which the Fano factor approaches 1/3. Surprisingly, the minimum conductance at these QDPs may be lower than that at the TDPs under certain conditions. This is remarkable as the minimum conductance attainable in graphene superlattices was believed to appear at TDPs. - Highlights: • Quasi-Dirac points (QDPs) are found for the first time in one-dimensional graphene superlattices. • The QDP is different from the traditional Dirac points (TDPs) in graphene superlattices. • The angular-averaged conductance reaches a minimum value at the QDPs, at which the Fano factor approaches 1/3. • The minimum conductance at these QDPs may be lower than that at the TDPs under certain conditions. • The minimum conductance attainable in graphene superlattices was believed to appear at TDPs.

  12. One-Dimensional Forward–Forward Mean-Field Games

    KAUST Repository

    Gomes, Diogo A.

    2016-11-01

    While the general theory for the terminal-initial value problem for mean-field games (MFGs) has achieved a substantial progress, the corresponding forward–forward problem is still poorly understood—even in the one-dimensional setting. Here, we consider one-dimensional forward–forward MFGs, study the existence of solutions and their long-time convergence. First, we discuss the relation between these models and systems of conservation laws. In particular, we identify new conserved quantities and study some qualitative properties of these systems. Next, we introduce a class of wave-like equations that are equivalent to forward–forward MFGs, and we derive a novel formulation as a system of conservation laws. For first-order logarithmic forward–forward MFG, we establish the existence of a global solution. Then, we consider a class of explicit solutions and show the existence of shocks. Finally, we examine parabolic forward–forward MFGs and establish the long-time convergence of the solutions.

  13. Neutron scattering studies of three one-dimensional antiferromagnets

    CERN Document Server

    Kenzelmann, M

    2001-01-01

    observed in the disordered phase of spin-1/2 chains. The magnetic order of the one-dimensional spin-1/2 XY antiferromagnet Cs sub 2 CoCl sub 4 was investigated using neutron diffraction. The magnetic structure has an ordering wave-vector (0, 0.5, 0.5) for T < 217 mK and the magnetic structure is a non-linear structure with the magnetic moments at a small angle to the b axis. Above a field of H = 2.1 T the magnetic order collapses in an apparent first order phase transition, suggesting a transition to a spin-liquid phase. Low-dimensional magnets with low-spin quantum numbers are ideal model systems for investigating strongly interacting macroscopic quantum ground states and their non-linear spin excitations. This thesis describes neutron scattering experiments of three one-dimensional low-spin antiferromagnets where strong quantum fluctuations lead to highly-correlated ground states and unconventional cooperative spin excitations. The excitation spectrum of the antiferromagnetic spin-1 Heisenberg chain CsNi...

  14. One-Dimensional Forward–Forward Mean-Field Games

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Diogo A., E-mail: diogo.gomes@kaust.edu.sa; Nurbekyan, Levon; Sedjro, Marc [King Abdullah University of Science and Technology (KAUST), CEMSE Division (Saudi Arabia)

    2016-12-15

    While the general theory for the terminal-initial value problem for mean-field games (MFGs) has achieved a substantial progress, the corresponding forward–forward problem is still poorly understood—even in the one-dimensional setting. Here, we consider one-dimensional forward–forward MFGs, study the existence of solutions and their long-time convergence. First, we discuss the relation between these models and systems of conservation laws. In particular, we identify new conserved quantities and study some qualitative properties of these systems. Next, we introduce a class of wave-like equations that are equivalent to forward–forward MFGs, and we derive a novel formulation as a system of conservation laws. For first-order logarithmic forward–forward MFG, we establish the existence of a global solution. Then, we consider a class of explicit solutions and show the existence of shocks. Finally, we examine parabolic forward–forward MFGs and establish the long-time convergence of the solutions.

  15. Bjorken flow in one-dimensional relativistic magnetohydrodynamics with magnetization

    CERN Document Server

    Pu, Shi; Rezzolla, Luciano; Rischke, Dirk H

    2016-01-01

    We study the one-dimensional, longitudinally boost-invariant motion of an ideal fluid with infinite conductivity in the presence of a transverse magnetic field, i.e., in the ideal transverse magnetohydrodynamical limit. In an extension of our previous work [1], we consider the fluid to have a non-zero magnetization. First, we assume a constant magnetic susceptibility $\\chi_{m}$ and consider an ultrarelativistic ideal gas equation of state. For a paramagnetic fluid (i.e., with $\\chi_{m}>0$), the decay of the energy density slows down since the fluid gains energy from the magnetic field. For a diamagnetic fluid (i.e., with $\\chi_{m}<0$), the energy density decays faster because it feeds energy into the magnetic field. Furthermore, when the magnetic field is taken to be external and to decay in proper time $\\tau$ with a power law $\\sim\\tau^{-a}$, two distinct solutions can be found depending on the values of $a$ and $\\chi_m$. Finally, we also solve the ideal magnetohydrodynamical equations for one-dimensional...

  16. One-dimensional densely aligned perovskite-decorated semiconductor heterojunctions with enhanced photocatalytic activity.

    Science.gov (United States)

    Wang, Mengye; Zheng, Dajiang; Ye, Meidan; Zhang, Chuchu; Xu, Binbin; Lin, Changjian; Sun, Lan; Lin, Zhiqun

    2015-03-25

    By using one-dimensional rutile TiO(2) nanorod arrays as the structure-directing scaffold as well as the TiO(2) source to two consecutive hydrothermal reactions, densely aligned SrTiO(3) -modified rutile TiO(2) heterojunction photocatalysts are crafted for the first time. The first hydrothermal processing yielded nanostructured rutile TiO(2) with the hollow openings on the top of nanorods (i.e., partially etched rutile TiO(2) nanorod arrays; denoted PE-TNRAs). The subsequent second hydrothermal treatment in the presence of Sr(2+) transforms the surface of partially etched rutile TiO(2) nanorods into SrTiO(3) nanoparticles via the concurrent dissolution of TiO(2) and precipitation of SrTiO(3) while retaining the cylindrical shape (i.e., forming SrTiO(3) -decorated rutile TiO(2) composite nanorods; denoted STO-TNRAs). The structural and composition characterizations substantiate the success in achieving STO-TNRA nanostructures. In comparison to PE-TNRAs, STO-TNRA photocatalysts exhibit higher photocurrents and larger photocatalytic degradation rates of methylene blue (3.21 times over PE-TNRAs) under UV light illumination as a direct consequence of improved charge carrier mobility and enhanced electron/hole separation. Such 1D perovskite-decorated semiconductor nanoarrays are very attractive for optoelectronic applications in photovoltaics, photocatalytic hydrogen production, among other areas.

  17. Design and Construction of a One-Dimensional DNA Track for an Artificial Molecular Motor

    Directory of Open Access Journals (Sweden)

    Suzana Kovacic

    2012-01-01

    Full Text Available DNA is a versatile heteropolymer that shows great potential as a building block for a diverse array of nanostructures. We present here a solution to the problem of designing and synthesizing a DNA-based nanostructure that will serve as the track along which an artificial molecular motor processes. This one-dimensional DNA track exhibits periodically repeating elements that provide specific binding sites for the molecular motor. Besides these binding elements, additional sequences are necessary to label specific regions within the DNA track and to facilitate track construction. Designing an ideal DNA track sequence presents a particular challenge because of the many variable elements that greatly expand the number of potential sequences from which the ideal sequence must be chosen. In order to find a suitable DNA sequence, we have adapted a genetic algorithm which is well suited for a large but sparse search space. This algorithm readily identifies long DNA sequences that include all the necessary elements to both facilitate DNA track construction and to present appropriate binding sites for the molecular motor. We have successfully experimentally incorporated the sequence identified by the algorithm into a long DNA track meeting the criteria for observation of the molecular motor's activity.

  18. Self-assembly of one-dimensional metal-organic nanoarchitectures on a surface

    Science.gov (United States)

    Capsoni, Martina; Schiffrin, Agustin; Shaw, Adam; Burke, Sarah

    2014-03-01

    Supramolecular chemistry holds promise for designing low-dimensional nanostructures with predefined functionalities. In particular, the interface between metal-organic complexes and surfaces is relevant in applications such as photovoltaics, photocatalysis, molecular electronics, etc. The structural, chemical and electronic properties of these systems can be dramatically altered by the interaction with the underlying surface. It is therefore of great relevance to achieve morphological control of functional nano-assemblies on a substrate at the single molecule and atom level. Here, we investigate the in situ coordination of bisterpyridine molecules with transition metal adatoms on Ag(111), by means of low-temperature scanning tunneling microscopy. The bare ligand adsorbs following specific orientations with respect to the substrate atomic lattice. Ordered supramolecular domains emerge via parallel adjacent non-covalent binding of the molecules. Coordination between deposited iron adatoms and terpyridine ligands is activated at room temperature, likely mediated by an intramolecular conformational change of the pyridine groups. The resulting self-assembled one-dimensional nanostructures are described.

  19. Correlation Effects in Kinetics of One-Dimensional Atomic Systems

    Directory of Open Access Journals (Sweden)

    V. D. Borman

    2013-01-01

    properties of 1D systems (such as spatial heterogeneity that is associated with strong density fluctuations, the lack of phase transitions, the presence of frozen disorder, confinement, and blocked movement of nuclear particle by its neighbours in nonequilibrium phenomena by considering the four examples. The anomalous transport in zeolite channels is considered. The mechanism of the transport may appear in carbon nanotubes and MOF structures, relaxation, mechanical properties, and stability of nonequilibrium states of free chains of metal atoms, non-Einstein atomic mobility in 1D atomic systems. Also we discuss atomic transport and separation of two-component mixture of atoms in a 1D system—a zeolite membrane with subnanometer channels. We discuss the atomic transport and separation of two-component mixture of atoms in a 1D system—zeolite membrane with subnanometer channels. These phenomena are described by the response function method for nonequilibrium systems of arbitrary density that allows us to calculate the dynamic response function and the spectrum of relaxation of density fluctuations 1D atomic system.

  20. Crystallographic shear mechanisms in Rh one-dimensional oxides

    Science.gov (United States)

    Hernando, María; Boulahya, Khalid; Parras, Marina; González-Calbet, José M.

    2005-02-01

    Electron diffraction and high resolution electron microscopy have been used to characterize two new one-dimensional superstructures in the A sbnd Rh sbnd O system (A = Ca, Sr) related to the 2H-ABO 3-type. They are formed by the intergrowth of n A 3A'BO 6 blocks, showing the Sr 4RhO 6-type, with A 12A' 2B 8O 30 blocks, constituted by two A 3O 9 and two A 3A'O 6 layers alternating in the stacking sequence 1:1, leading to the A 27A' 7B 13O 60 ( n=5) and A 30A' 8B 14O 66 ( n=6) compositions. A crystallographic shear mechanism is proposed to describe the structural relationship between Sr 4RhO 6 (A 3A'BO 6-type) and the new superstructures.

  1. One-dimensional modeling of piping flow erosion

    Science.gov (United States)

    Lachouette, Damien; Golay, Frédéric; Bonelli, Stéphane

    2008-09-01

    A process called "piping", which often occurs in water-retaining structures (earth-dams, dykes, levees), involving the formation and progression of a continuous tunnel between the upstream and downstream sides, is one of the main cause of structure failure. Starting with the diphasic flow volume equations and the jump equations including the erosion processes, a simplified one-dimensional model for two-phase piping flow erosion was developed. The numerical simulation based on constant input and output pressures showed that the particle concentration can be a significant factor at the very beginning of the process, resulting in the enlargement of the hole at the exit. However, it was concluded that this influence is a secondary factor: the dilute flow assumption, which considerably simplifies the description, is relevant here. To cite this article: D. Lachouette et al., C. R. Mecanique 336 (2008).

  2. Impedance of rigid bodies in one-dimensional elastic collisions

    CERN Document Server

    Santos, Janilo; Nelson, Osman Rosso

    2012-01-01

    In this work we study the problem of one-dimensional elastic collisions of billiard balls, considered as rigid bodies, in a framework very different from the classical one presented in text books. Implementing the notion of impedance matching as a way to understand eficiency of energy transmission in elastic collisions, we find a solution which frames the problem in terms of this conception. We show that the mass of the ball can be seen as a measure of its impedance and verify that the problem of maximum energy transfer in elastic collisions can be thought of as a problem of impedance matching between different media. This approach extends the concept of impedance, usually associated with oscillatory systems, to system of rigid bodies.

  3. Configurational and energy landscape in one-dimensional Coulomb systems.

    Science.gov (United States)

    Varela, Lucas; Téllez, Gabriel; Trizac, Emmanuel

    2017-02-01

    We study a one-dimensional Coulomb system, where two charged colloids are neutralized by a collection of point counterions, with global neutrality. With temperature being given, two situations are addressed: Either the colloids are kept at fixed positions (canonical ensemble) or the force acting on the colloids is fixed (isobaric-isothermal ensemble). The corresponding partition functions are worked out exactly, in view of determining which arrangement of counterions is optimal. How many counterions should be in the confined segment between the colloids? For the remaining ions outside, is there a left-right symmetry breakdown? We evidence a cascade of transitions as system size is varied in the canonical treatment or as pressure is increased in the isobaric formulation.

  4. The statistical distributions of one-dimensional “turbulence”

    Science.gov (United States)

    Peyrard, Michel

    2004-06-01

    We study a one-dimensional discrete analog of the von Kármán flow widely investigated in turbulence, made of a lattice of anharmonic oscillators excited by both ends in the presence of a dissipative term proportional to the second-order finite difference of the velocities, similar to the viscous term in a fluid. The dynamics of the model shows striking similarities with an actual turbulent flow, both at local and global scales. Calculations of the probability distribution function of velocity increments, extensively studied in turbulence, with a very large number of points in order to determine accurately the statistics of rare events, allow us to provide a meaningful comparison of different theoretical expressions of the PDFs.

  5. Scale dependent partitioning of one-dimensional aperiodic set diffraction

    Science.gov (United States)

    Elkharrat, A.

    2004-06-01

    We give a multiresolution partition of pure point parts of diffraction patterns of one-dimensional aperiodic sets. When an aperiodic set is related to the Golden Ratio, denoted by tau, it is well known that the pure point part of its diffractive measure is supported by the extension ring of tau, denoted by mathbb{Z}[tau]. The partition we give is based on the formalism of the so called tau-integers, denoted by mathbb{Z}_tau. The set of tau-integers is a selfsimilar set obeying mathbb{Z}_tau/tau^{j-1}subsetmathbb{Z}_tau/tau^j subset mathbb{Z}_tau/tau^{j + 1} subsetmathbb{Z}[tau], jinmathbb{Z}. The pure point spectrum is then partitioned with respect to this “Russian doll” like sequence of subsets mathbb{Z}_tau/tau^j. Thus we deduce the partition of the pure point part of the diffractive measure of aperiodic sets.

  6. Explicit Solutions for One-Dimensional Mean-Field Games

    KAUST Repository

    Prazeres, Mariana

    2017-04-05

    In this thesis, we consider stationary one-dimensional mean-field games (MFGs) with or without congestion. Our aim is to understand the qualitative features of these games through the analysis of explicit solutions. We are particularly interested in MFGs with a nonmonotonic behavior, which corresponds to situations where agents tend to aggregate. First, we derive the MFG equations from control theory. Then, we compute explicit solutions using the current formulation and examine their behavior. Finally, we represent the solutions and analyze the results. This thesis main contributions are the following: First, we develop the current method to solve MFG explicitly. Second, we analyze in detail non-monotonic MFGs and discover new phenomena: non-uniqueness, discontinuous solutions, empty regions and unhappiness traps. Finally, we address several regularization procedures and examine the stability of MFGs.

  7. Numerical method of characteristics for one-dimensional blood flow

    CERN Document Server

    Acosta, Sebastian; Riviere, Beatrice; Penny, Daniel J; Rusin, Craig G

    2014-01-01

    Mathematical modeling at the level of the full cardiovascular system requires the numerical approximation of solutions to a one-dimensional nonlinear hyperbolic system describing flow in a single vessel. This model is often simulated by computationally intensive methods like finite elements and discontinuous Galerkin, while some recent applications require more efficient approaches (e.g. for real-time clinical decision support, phenomena occurring over multiple cardiac cycles, iterative solutions to optimization/inverse problems, and uncertainty quantification). Further, the high speed of pressure waves in blood vessels greatly restricts the time-step needed for stability in explicit schemes. We address both cost and stability by presenting an efficient and unconditionally stable method for approximating solutions to diagonal nonlinear hyperbolic systems. Theoretical analysis of the algorithm is given along with a comparison of our method to a discontinuous Galerkin implementation. Lastly, we demonstrate the ...

  8. Study on pile drivability with one dimensional wave propagation theory

    Institute of Scientific and Technical Information of China (English)

    陈仁朋; 王仕方; 陈云敏

    2003-01-01

    Pile drivability is a key problem during the stage of design and construction installation of pile foundations. The solution to the one dimensional wave equation was used to determine the impact force at the top of a concrete pile for a given ram mass, cushion stiffness, and pile impedance. The kinematic equation of pile toe was established and solved based on wave equation theory. The movements of the pile top and pile toe were presented, which clearly showed the dynamic displacement, including rebound and penetration of pile top and toe. A parametric study was made with a full range of practical values of ram weight, cushion stiffness, dropheight, and pile impedance. Suggestions for optimizing the parameters were also presented. Comparisons between the results obtained by the present solution and in-situ measurements indicated the reliability and validity of the method.

  9. Testing of a one dimensional model for Field II calibration

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten

    2008-01-01

    to the calibrated Field II program for 1, 4, and 10 cycle excitations. Two parameter sets were applied for modeling, one real valued Pz27 parameter set, manufacturer supplied, and one complex valued parameter set found in literature, Alguer´o et al. [11]. The latter implicitly accounts for attenuation. Results show......Field II is a program for simulating ultrasound transducer fields. It is capable of calculating the emitted and pulse-echoed fields for both pulsed and continuous wave transducers. To make it fully calibrated a model of the transducer’s electro-mechanical impulse response must be included. We...... examine an adapted one dimensional transducer model originally proposed by Willatzen [9] to calibrate Field II. This model is modified to calculate the required impulse responses needed by Field II for a calibrated field pressure and external circuit current calculation. The testing has been performed...

  10. Coherent backscattering of light off one-dimensional atomic strings

    CERN Document Server

    Sørensen, H L; Kluge, K W; Iakoupov, I; Sørensen, A S; Müller, J H; Polzik, E S; Appel, J

    2016-01-01

    Bragg scattering, well known in crystallography, has become a powerful tool for artificial atomic structures such as optical lattices. In an independent development photonic waveguides have been used successfully to boost quantum light-matter coupling. We combine these two lines of research and present the first experimental realisation of coherent Bragg scattering off a one-dimensional (1D) system - two strings of atoms strongly coupled to a single photonic mode - realised by trapping atoms in the evanescent field of a tapered optical fibre (TOF), which also guides the probe light. We report nearly 12% power reflection from strings containing only about one thousand caesium atoms, an enhancement of more than two orders of magnitude compared to reflection from randomly positioned atoms. This result paves the road towards collective strong coupling in 1D atom-photon systems. Our approach also allows for a straightforward fibre connection between several distant 1D atomic crystals.

  11. Properties of surface modes in one dimensional plasma photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, S.; Prasad, S., E-mail: prasad.surendra@gmail.com; Singh, V. [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India)

    2015-02-15

    Properties of surface modes supported at the interface of air and a semi-infinite one dimensional plasma photonic crystal are analyzed. The surface mode equation is obtained by using transfer matrix method and applying continuity conditions of electric fields and its derivatives at the interface. It is observed that with increase in the width of cap layer, frequencies of surface modes are shifted towards lower frequency side, whereas increase in tangential component of wave-vector increases the mode frequency and total energy carried by the surface modes. With increase in plasma frequency, surface modes are found to shift towards higher frequency side. The group velocity along interface is found to control by cap layer thickness.

  12. Singularity formation for one dimensional full Euler equations

    Science.gov (United States)

    Pan, Ronghua; Zhu, Yi

    2016-12-01

    We investigate the basic open question on the global existence v.s. finite time blow-up phenomena of classical solutions for the one-dimensional compressible Euler equations of adiabatic flow. For isentropic flows, it is well-known that the solutions develop singularity if and only if initial data contain any compression (the Riemann variables have negative spatial derivative). The situation for non-isentropic flow is not quite clear so far, due to the presence of non-constant entropy. In [4], it is shown that initial weak compressions do not necessarily develop singularity in finite time, unless the compression is strong enough for general data. In this paper, we identify a class of solutions of the full (non-isentropic) Euler equations, developing singularity in finite time even though their initial data do not contain any compression. This is in sharp contrast to the isentropic flow.

  13. One-dimensional topological edge states of bismuth bilayers

    Science.gov (United States)

    Drozdov, Ilya K.; Alexandradinata, A.; Jeon, Sangjun; Nadj-Perge, Stevan; Ji, Huiwen; Cava, R. J.; Andrei Bernevig, B.; Yazdani, Ali

    2014-09-01

    The hallmark of a topologically insulating state of matter in two dimensions protected by time-reversal symmetry is the existence of chiral edge modes propagating along the perimeter of the sample. Among the first systems predicted to be a two-dimensional topological insulator are bilayers of bismuth. Here we report scanning tunnelling microscopy experiments on bulk Bi crystals that show that a subset of the predicted Bi-bilayers' edge states are decoupled from the states of the substrate and provide direct spectroscopic evidence of their one-dimensional nature. Moreover, by visualizing the quantum interference of edge-mode quasi-particles in confined geometries, we demonstrate their remarkable coherent propagation along the edge with scattering properties consistent with strong suppression of backscattering as predicted for the propagating topological edge states.

  14. SUSY-inspired one-dimensional transformation optics

    CERN Document Server

    Miri, Mohammad-Ali; Christodoulides, Demetrios N

    2014-01-01

    Transformation optics aims to identify artificial materials and structures with desired electromagnetic properties by means of pertinent coordinate transformations. In general, such schemes are meant to appropriately tailor the constitutive parameters of metamaterials in order to control the trajectory of light in two and three dimensions. Here we introduce a new class of one-dimensional optical transformations that exploits the mathematical framework of supersymmetry (SUSY). This systematic approach can be utilized to synthesize photonic configurations with identical reflection and transmission characteristics, down to the phase, for all incident angles, thus rendering them perfectly indistinguishable to an external observer. Along these lines, low-contrast dielectric arrangements can be designed to fully mimic the behavior of a given high-contrast structure that would have been otherwise beyond the reach of available materials and existing fabrication techniques. Similar strategies can also be adopted to re...

  15. Characterizing high- n quasi-one-dimensional strontium Rydberg atoms

    Science.gov (United States)

    Hiller, Moritz; Yoshida, Shuhei; Burgdörfer, Joachim; Ye, Shuzhen; Zhang, Xinyue; Dunning, F. Barry

    2014-05-01

    The production of high- n, n ~ 300 , quasi-one-dimensional strontium Rydberg atoms by two-photon excitation of selected extreme Stark states in the presence of a weak dc field is examined using a crossed laser-atom beam geometry. The polarization of the product states is probed using three independent techniques which are analyzed with the aid of classical-trajectory Monte Carlo simulations that employ initial ensembles based on quantum calculations using a two-active-electron model. Comparisons between theory and experiment demonstrate that the product states have large dipole moments, ~ 1 . 0 - 1 . 2n2 a . u . and that they can be engineered using pulsed electric fields to create a wide variety of target states. Research supported by the NSF, the Robert A Welch Foundation, and the FWF (Austria).

  16. Topologically protected states in one-dimensional systems

    CERN Document Server

    Fefferman, C L; Weinstein, M I

    2017-01-01

    The authors study a class of periodic Schrödinger operators, which in distinguished cases can be proved to have linear band-crossings or "Dirac points". They then show that the introduction of an "edge", via adiabatic modulation of these periodic potentials by a domain wall, results in the bifurcation of spatially localized "edge states". These bound states are associated with the topologically protected zero-energy mode of an asymptotic one-dimensional Dirac operator. The authors' model captures many aspects of the phenomenon of topologically protected edge states for two-dimensional bulk structures such as the honeycomb structure of graphene. The states the authors construct can be realized as highly robust TM-electromagnetic modes for a class of photonic waveguides with a phase-defect.

  17. Thermal radiation in one-dimensional photonic quasicrystals with graphene

    Science.gov (United States)

    Costa, C. H.; Vasconcelos, M. S.; Fulco, U. L.; Albuquerque, E. L.

    2017-10-01

    In this work we investigate the thermal power spectra of the electromagnetic radiation through one-dimensional stacks of dielectric layers, with graphene at their interfaces, arranged according to a quasiperiodic structure obeying the Fibonacci (FB), Thue-Morse (TM) and double-period (DP) sequences. The thermal radiation power spectra are determined by means of a theoretical model based on a transfer matrix formalism for both normal and oblique incidence geometries, considering the Kirchhoff's law of thermal radiation. A systematic study of the consequences of the graphene layers in the thermal emittance spectra is presented and discussed. We studied also the radiation spectra considering the case where the chemical potential is changed in order to tune the omnidirectional photonic band gap.

  18. One-dimensional quasi-relativistic particle in the box

    CERN Document Server

    Kaleta, Kamil; Malecki, Jacek

    2011-01-01

    Two-term Weyl-type asymptotic law for the eigenvalues of one-dimensional quasi-relativistic Hamiltonian (-h^2 c^2 d^2/dx^2 + m^2 c^4)^(1/2) + V_well(x) (the Klein-Gordon square-root operator with electrostatic potential) with the infinite square well potential V_well(x) is given: the n-th eigenvalue is equal to (n pi/2 - pi/8) h c/a + O(1/n), where 2a is the width of the potential well. Simplicity of eigenvalues is proved. Some L^2 and L^infinity properties of eigenfunctions are also studied. Eigenvalues represent energies of a `massive particle in the box' quasi-relativistic model.

  19. Novel superconducting phenomena in quasi-one-dimensional Bechgaard salts

    Science.gov (United States)

    Jerome, Denis; Yonezawa, Shingo

    2016-03-01

    It is the saturation of the transition temperature Tc in the range of 24 K for known materials in the late sixties that triggered the search for additional materials offering new coupling mechanisms leading in turn to higher Tc's. As a result of this stimulation, superconductivity in organic matter was discovered in tetramethyl-tetraselenafulvalene-hexafluorophosphate, (TMTSF)2PF6, in 1979, in the laboratory founded at Orsay by Professor Friedel and his colleagues in 1962. Although this conductor is a prototype example for low-dimensional physics, we mostly focus in this article on the superconducting phase of the ambient-pressure superconductor (TMTSF)2ClO4, which has been studied most intensively among the TMTSF salts. We shall present a series of experimental results supporting nodal d-wave symmetry for the superconducting gap in these prototypical quasi-one-dimensional conductors. xml:lang="fr"

  20. One-Dimensional Time to Explosion (Thermal Sensitivity) of ANPZ

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hust, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McClelland, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gresshoff, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-11-12

    Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 C) and the violence from thermal explosion may cause a significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to explosion, threshold thermal explosion temperature, and determine kinetic parameters of energetic materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. This report summarizes the recent ODTX experimental data and modeling results for 2,6-diamino-3,5-dintropyrazine (ANPZ).

  1. Capillary condensation in one-dimensional irregular confinement

    Science.gov (United States)

    Handford, Thomas P.; Pérez-Reche, Francisco J.; Taraskin, Sergei N.

    2013-07-01

    A lattice-gas model with heterogeneity is developed for the description of fluid condensation in finite sized one-dimensional pores of arbitrary shape. Mapping to the random-field Ising model allows an exact solution of the model to be obtained at zero-temperature, reproducing the experimentally observed dependence of the amount of fluid adsorbed in the pore on external pressure. It is demonstrated that the disorder controls the sorption for long pores and can result in H2-type hysteresis. Finite-temperature Metropolis dynamics simulations support analytical findings in the limit of low temperatures. The proposed framework is viewed as a fundamental building block of the theory of capillary condensation necessary for reliable structural analysis of complex porous media from adsorption-desorption data.

  2. Compaction of quasi-one-dimensional elastoplastic materials

    Science.gov (United States)

    Shaebani, M. Reza; Najafi, Javad; Farnudi, Ali; Bonn, Daniel; Habibi, Mehdi

    2017-06-01

    Insight into crumpling or compaction of one-dimensional objects is important for understanding biopolymer packaging and designing innovative technological devices. By compacting various types of wires in rigid confinements and characterizing the morphology of the resulting crumpled structures, here, we report how friction, plasticity and torsion enhance disorder, leading to a transition from coiled to folded morphologies. In the latter case, where folding dominates the crumpling process, we find that reducing the relative wire thickness counter-intuitively causes the maximum packing density to decrease. The segment size distribution gradually becomes more asymmetric during compaction, reflecting an increase of spatial correlations. We introduce a self-avoiding random walk model and verify that the cumulative injected wire length follows a universal dependence on segment size, allowing for the prediction of the efficiency of compaction as a function of material properties, container size and injection force.

  3. Charge diffusion in the one-dimensional Hubbard model

    Science.gov (United States)

    Steinigeweg, R.; Jin, F.; De Raedt, H.; Michielsen, K.; Gemmer, J.

    2017-08-01

    We study the real-time and real-space dynamics of charge in the one-dimensional Hubbard model in the limit of high temperatures. To this end, we prepare pure initial states with sharply peaked density profiles and calculate the time evolution of these nonequilibrium states, by using numerical forward-propagation approaches to chains as long as 20 sites. For a class of typical states, we find excellent agreement with linear-response theory and unveil the existence of remarkably clean charge diffusion in the regime of strong particle-particle interactions. We additionally demonstrate that, in the half-filling sector, this diffusive behavior does not depend on certain details of our initial conditions, i.e., it occurs for five different realizations with random and nonrandom internal degrees of freedom, single and double occupation of the central site, and displacement of spin-up and spin-down particles.

  4. A one-dimensional toy model of globular clusters

    CERN Document Server

    Fanelli, D; Ruffo, S; Fanelli, Duccio; Merafina, Marco; Ruffo, Stefano

    2001-01-01

    We introduce a one-dimensional toy model of globular clusters. The model is a version of the well-known gravitational sheets system, where we take additionally into account mass and energy loss by evaporation of stars at the boundaries. Numerical integration by the "exact" event-driven dynamics is performed, for initial uniform density and Gaussian random velocities. Two distinct quasi-stationary asymptotic regimes are attained, depending on the initial energy of the system. We guess the forms of the density and velocity profiles which fit numerical data extremely well and allow to perform an independent calculation of the self-consistent gravitational potential. Some power-laws for the asymptotic number of stars and for the collision times are suggested.

  5. Magnons in one-dimensional k-component Fibonacci structures

    Science.gov (United States)

    Costa, C. H.; Vasconcelos, M. S.

    2014-05-01

    We have studied the magnon transmission through of one-dimensional magnonic k-component Fibonacci structures, where k different materials are arranged in accordance with the following substitution rule: Sn(k)=Sn-1(k)Sn-k(k) (n ≥k=0,1,2,…), where Sn(k) is the nth stage of the sequence. The calculations were carried out in exchange dominated regime within the framework of the Heisenberg model and taking into account the RPA approximation. We have considered multilayers composed of simple cubic spin-S Heisenberg ferromagnets, and, by using the powerful transfer-matrix method, the spin wave transmission is obtained. It is demonstrated that the transmission coefficient has a rich and interesting magnonic pass- and stop-bands structures, which depends on the frequency of magnons and the k values.

  6. Magnons in one-dimensional k-component Fibonacci structures

    Energy Technology Data Exchange (ETDEWEB)

    Costa, C. H., E-mail: carloshocosta@hotmail.com [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Vasconcelos, M. S. [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil)

    2014-05-07

    We have studied the magnon transmission through of one-dimensional magnonic k-component Fibonacci structures, where k different materials are arranged in accordance with the following substitution rule: S{sub n}{sup (k)}=S{sub n−1}{sup (k)}S{sub n−k}{sup (k)} (n≥k=0,1,2,…), where S{sub n}{sup (k)} is the nth stage of the sequence. The calculations were carried out in exchange dominated regime within the framework of the Heisenberg model and taking into account the RPA approximation. We have considered multilayers composed of simple cubic spin-S Heisenberg ferromagnets, and, by using the powerful transfer-matrix method, the spin wave transmission is obtained. It is demonstrated that the transmission coefficient has a rich and interesting magnonic pass- and stop-bands structures, which depends on the frequency of magnons and the k values.

  7. Well-posedness of one-dimensional Korteweg models

    Directory of Open Access Journals (Sweden)

    Sylvie Benzoni-Gavage

    2006-05-01

    Full Text Available We investigate the initial-value problem for one-dimensional compressible fluids endowed with internal capillarity. We focus on the isothermal inviscid case with variable capillarity. The resulting equations for the density and the velocity, consisting of the mass conservation law and the momentum conservation with Korteweg stress, are a system of third order nonlinear dispersive partial differential equations. Additionally, this system is Hamiltonian and admits travelling solutions, representing propagating phase boundaries with internal structure. By change of unknown, it roughly reduces to a quasilinear Schrodinger equation. This new formulation enables us to prove local well-posedness for smooth perturbations of travelling profiles and almost-global existence for small enough perturbations. A blow-up criterion is also derived.

  8. Magnetic properties of manganese based one-dimensional spin chains.

    Science.gov (United States)

    Asha, K S; Ranjith, K M; Yogi, Arvind; Nath, R; Mandal, Sukhendu

    2015-12-14

    We have correlated the structure-property relationship of three manganese-based inorganic-organic hybrid structures. Compound 1, [Mn2(OH-BDC)2(DMF)3] (where BDC = 1,4-benzene dicarboxylic acid and DMF = N,N'-dimethylformamide), contains Mn2O11 dimers as secondary building units (SBUs), which are connected by carboxylate anions forming Mn-O-C-O-Mn chains. Compound 2, [Mn2(BDC)2(DMF)2], contains Mn4O20 clusters as SBUs, which also form Mn-O-C-O-Mn chains. In compound 3, [Mn3(BDC)3(DEF)2] (where DEF = N,N'-diethylformamide), the distorted MnO6 octahedra are linked to form a one-dimensional chain with Mn-O-Mn connectivity. The magnetic properties were investigated by means of magnetization and heat capacity measurements. The temperature dependent magnetic susceptibility of all the three compounds could be nicely fitted using a one-dimensional S = 5/2 Heisenberg antiferromagnetic chain model and the value of intra-chain exchange coupling (J/k(B)) between Mn(2+) ions was estimated to be ∼1.1 K, ∼0.7 K, and ∼0.46 K for compounds 1, 2, and 3, respectively. Compound 1 does not undergo any magnetic long-range-order down to 2 K while compounds 2 and 3 undergo long-range magnetic order at T(N) ≈ 4.2 K and ≈4.3 K, respectively, which are of spin-glass type. From the values of J/k(B) and T(N) the inter-chain coupling (J(⊥)/k(B)) was calculated to be about 0.1J/k(B) for both compounds 2 and 3, respectively.

  9. A One-Dimensional Synthetic-Aperture Microwave Radiometer

    Science.gov (United States)

    Doiron, Terence; Piepmeier, Jeffrey

    2010-01-01

    A proposed one-dimensional synthetic- aperture microwave radiometer could serve as an alternative to either the two-dimensional synthetic-aperture radiometer described in the immediately preceding article or to a prior one-dimensional one, denoted the Electrically Scanned Thinned Array Radiometer (ESTAR), mentioned in that article. The proposed radiometer would operate in a pushbroom imaging mode, utilizing (1) interferometric cross-track scanning to obtain cross-track resolution and (2) the focusing property of a reflector for along-track resolution. The most novel aspect of the proposed system would be the antenna (see figure), which would include a cylindrical reflector of offset parabolic cross section. The reflector could be made of a lightweight, flexible material amenable to stowage and deployment. Other than a stowage/deployment mechanism, the antenna would not include moving parts, and cross-track scanning would not entail mechanical rotation of the antenna. During operation, the focal line, parallel to the cylindrical axis, would be oriented in the cross-track direction, so that placement of receiving/radiating elements at the focal line would afford the desired along-track resolution. The elements would be microwave feed horns sparsely arrayed along the focal line. The feed horns would be oriented with their short and long cross-sectional dimensions parallel and perpendicular, respectively, to the cylindrical axis to obtain fan-shaped beams having their broad and narrow cross-sectional dimensions parallel and perpendicular, respectively, to the cylindrical axis. The interference among the beams would be controlled in the same manner as in the ESTAR to obtain along-cylindrical- axis (cross-track) resolution and cross-track scanning.

  10. Analysis of Polaron Band Formation with the One-Dimensional Holstein Model

    Institute of Scientific and Technical Information of China (English)

    GE Ming; QIN Gan; WAN Shao-Long

    2005-01-01

    @@ We present an analytic result of the polaronic band structure by using the one-dimensional Holstein model on an infinite lattice. The single-phonon effect is used to investigate the ground state properties, such as the polaronic band structure, ground state energy, phonon distribution and effective mass, which agree with the numerical and analytic results obtained recently in the region from the weak coupling to the intermediate coupling.

  11. Effect of surface nanostructure on temperature programmed reaction spectroscopy

    Science.gov (United States)

    Rieger, Michael; Rogal, Jutta; Reuter, Karsten

    2008-03-01

    Using the catalytic CO oxidation at RuO2(110) as a showcase, we employ first-principles kinetic Monte Carlo simulations to illustrate the intricate effects on temperature programmed reaction (TPR) spectroscopy data brought about by the mere correlations between the locations of the active sites at a nanostructured surface. Even in the absence of lateral interactions, this nanostructure alone can cause inhomogeneities that cannot be grasped by prevalent mean-field data analysis procedures, which thus lead to wrong conclusions on the reactivity of the different surface species. The RuO2(110) surface studied here exhibits only two prominent active sites, arranged in simple alternating rows. Yet, the mere neglection of this still quite trivial nanostructure leads mean-field TPR data analysis [1] to extract kinetic parameters that are in error by several orders of magnitude and that do not even reflect the relative reactivity of the different surface species correctly [2].[1] S. Wendt, M. Knapp, and H. Over, JACS 126, 1537 (2004).[2] M. Rieger, J. Rogal, and K. Reuter, Phys. Rev. Lett (in press).

  12. Three species one-dimensional kinetic model for weakly ionized plasmas

    CERN Document Server

    Gonzalez, J; Tierno, S P

    2016-01-01

    A three species one-dimensional kinetic model is presented for a spatially homogeneous weakly ionized plasma subjected to the action of a time varying electric field. Planar geometry is assumed, which means that the plasma dynamics evolves in the privileged direction of the field. The energy transmitted to the charges is be channelized to the neutrals thanks to collisions and impacting the plasma dynamics. Charge-charge interactions have been designed as a one dimensional collision term equivalent to the Landau operator used for fully ionized plasmas. Charge-neutral collisions are modelled by a conservative drift diffusion operator in the Doughertys form. The resulting set of coupled drift diffusion equations is solved with the stable and robust Propagator Integral Method. This method feasibility accounts for non-linear effects without appealing to linearisation or simplifications, providing conservative physically meaningful solutions. It is found that charge neutral collisions exert a significant effect sin...

  13. Infrared spectroscopy of one-dimensional metallic nanostructures on silicon vicinal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, Chung Vu

    2010-06-23

    Vicinal silicon(111) surfaces are used as templates for the growth of lead nanowires as well as gold and indium atom chains. The morphology of the Au atom chains was studied by use of Scanning Tunneling Microscopy (STM) and Reflection High Energy Electron Diffraction (RHEED). The In chains were investigated by infrared spectroscopy with the electrical field component of the IR light polarized either parallel or perpendicular to the wires. It is shown that at room temperature, In atom-chains display a plasmonic absorption feature along the chain but not in the perpendicular direction. Furthermore, upon cooling down to liquid nitrogen temperature, a metal to insulator transition is observed. A structural distortion is also confirmed by RHEED. As for the result of Pb nanowires, by means of infrared spectroscopy, it is now possible to control the average length of parallel nanowire arrays by monitoring four experimental parameters that influence on the nucleation density; namely: Pb coverage, evaporation rate, substrate temperature and the surface itself. The system shows an enhancement of the absorption at the antenna frequency in the low temperature regime. This scenario is assigned to the reduction of electron-phonon scattering due to low temperature. (orig.)

  14. Size dependent properties of one dimensional CdSe micro/nanostructures

    Science.gov (United States)

    Narula, Chetna; Chauhan, R. P.

    2017-09-01

    Cadmium Selenide (CdSe) micro/nanowires of different diameters were synthesized in polycarbonate membranes on copper substrate by template assisted electro-deposition method at room temperature. The structure, morphology, elemental, optical and electrical properties of CdSe micro/nanowires were investigated using X-ray Diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) spectroscopy, photoluminescence (PL) spectroscopy and probe station assisted with Keithley source meter. Structural analysis by X-ray diffraction depicted polycrystalline nature with hexagonal phase of micro/nanowires at all diameters. An increase in the value of average crystallite size was seen with increase in diameter. Morphological investigation confirmed the micro/nanowire synthesis and revealed an ordered array of prepared CdSe micro/nanowires of uniform diameters and having high aspect ratios. Optical band gap is found to increase from 1.89eV to 2.24 eV as the diameter is decreased from 1 μm to 50 nm. Using the band gap values, refractive index and optical dielectric constants (static and high frequency) were also evaluated. The electrical conductivity of CdSe micro/nanowires varied from 21.58 × 102 Ω-1 m-1to 1.93 × 102 Ω-1 m-1 when diameter was decreased. These semiconducting micro/nanowires arrays of different diameters may have potential applications in future nanoscale based electronic and optoelectronic devices.

  15. Synthesis and Characterization of SnO2 One-dimensional Nanostructures

    Institute of Scientific and Technical Information of China (English)

    李宗木; 徐法强

    2005-01-01

    Single-crystalline SnO2 nanowires have been successfully prepared in large scale on Au-coated silicon substrate by heating the mixture of self-made high-purity SnO2 powders and graphite powders at 900℃. Besides the line type nanowires some more features were observed. The products were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and Raman spectrum techniques. The results indicate that the tin dioxide nanowires have a rutile structure with diameters ranging from 30 to 120 nm and lengths up to several tens of micrometers. The possible mechanism of the growth and reaction for the nanowires was also discussed.

  16. One-Dimensional TiO2 Nanostructures as Photoanodes for Dye-Sensitized Solar Cells

    OpenAIRE

    Jie Qu; Chao Lai

    2013-01-01

    Titanium dioxide (TiO2) is star materials due to its remarkable optical and electronic properties, resulting in various applications, especially in the fields of dye-sensitized solar cells (DSSCs). Photoanode is the most important part of the DSSCs, which help to adsorb dye molecules and transport the injected electrons. The size, structure, and morphology of TiO2 photoanode have been found to show significant influence on the photovoltaic performance of DSSCs. In this paper, we briefly summa...

  17. Asymmetric Heat Conduction in One-Dimensional Hard-Point Model with Mass Gradient

    Institute of Scientific and Technical Information of China (English)

    LI Hai-Bin; NIE Qing-Miao; XIN Xiao-Tian

    2009-01-01

    The heat conduction in a one-dimensional (1D) hard-point model with mass gradient is studied. Using numerical simulation, we find an asymmetric heat conduction in this model with greater heat current in the direction of mass increase. The increase of temperature gradient, mass gradient and system size are found to enhance the asymmetric heat conduction. Based on the collision dynamic of a hard-point particle, we give a qualitative explanation for the underlying mechanism of asymmetric effect.

  18. Observation of localized flat-band modes in a one-dimensional photonic rhombic lattice

    CERN Document Server

    Mukherjee, Sebabrata

    2015-01-01

    We experimentally demonstrate the photonic realization of a dispersionless flat-band in a one-dimensional photonic rhombic lattice fabricated by ultrafast laser inscription. In the nearest neighbor tight binding approximation the lattice supports two dispersive and a non-dispersive (flat) band. We experimentally excite a superposition of flat-band eigen modes at the input of the photonic lattice and show the diffractionless propagation of the input modes due to their infinite effective mass.

  19. Transmission gaps in one-dimensional Fibonacci quasiperiodic structure containing epsilon-negative materials

    Indian Academy of Sciences (India)

    Hadi Rahimi; Abdolrahman Namdar; Samad Roshan Entezar; Habib Tajalli

    2010-05-01

    We investigate the transmission properties of one-dimensional Fibonacci quasiperiodic structure consisting of dispersive and lossless epsilon-negative (ENG) materials. It is found that for both TE and TM polarizations with normal and oblique incidences, there exist transmission gaps which are invariant with a change of scale and sensitive to incident angles. Analytical methods based on transfer matrices and effective medium theory have been used to explain the properties of transmission gaps.

  20. Photonic band structure of one-dimensional aperiodic superlattices composed of negative refraction metamaterials

    Science.gov (United States)

    Tyc, Michał H.; Salejda, Włodzimierz; Klauzer-Kruszyna, Agnieszka; Tarnowski, Karol

    2007-05-01

    The dispersion relation for polarized light transmitting through a one-dimensional superlattice composed of aperiodically arranged layers made of ordinary dielectric and negative refraction metamaterials is calculated with finite element method. Generalized Fibonacci, generalized Thue-Morse, double-periodic and Rudin-Shapiro superlattices are investigated, using their periodic approximants. Strong dispersion of metamaterials is taken into account. Group velocities and effective refraction indices in the structures are calculated. The self-similar structure of the transmission spectra is observed.

  1. Light propagation in tunable exciton-polariton one-dimensional photonic crystals

    CERN Document Server

    Sedov, E S; Arakelian, S M; Kavokin, A V

    2016-01-01

    Simulations of propagation of light beams in specially designed multilayer semiconductor structures (one-dimensional photonic crystals) with embedded quantum wells reveal characteristic optical properties of resonant hyperbolic metamaterials. A strong dependence of the refraction angle and the optical beam spread on the exciton radiative lifetime is revealed. We demonstrate the strong negative refraction of light and the control of the group velocity of light by an external bias through its effect upon the exciton radiative properties.

  2. Modeling of Z-scan characteristics for one-dimensional nonlinear photonic bandgap materials.

    Science.gov (United States)

    Chen, Shuqi; Zang, Weiping; Schülzgen, Axel; Liu, Xin; Tian, Jianguo; Moloney, Jerome V; Peyghambarian, Nasser

    2009-12-01

    We propose a Z-scan theory for one-dimensional nonlinear photonic bandgap materials. The Z-scan characteristics for this material are analyzed. Results show that the Z-scan curves for photonic bandgap materials with nonlinear refraction are similar to those of uniform materials exhibiting both nonlinear refraction and nonlinear absorption simultaneously. Effects of nonlinear absorption on reflected and transmitted Z-scan results are also discussed.

  3. The contact conductance of a one-dimensional wire partly embedded in a superconductor

    OpenAIRE

    Matthews, Raphael; Agam, Oded

    2007-01-01

    The conductance through a semi-infinite one-dimensional wire, partly embedded in a superconducting bulk electrode, is studied. When the electron-electron interactions within the wire are strongly repulsive, the wire effectively decouples from the superconductor. If they are moderately or weakly repulsive, the proximity of the superconductor induces superconducting order in the segment of the wire embedded in it. In this case it is shown that the conductance exhibits a crossover from conductiv...

  4. One-dimensional Fibonacci grating for far-field super-resolution imaging.

    Science.gov (United States)

    Wu, Kedi; Wang, Guo Ping

    2013-06-15

    One-dimensional Fibonacci gratings are used to transform evanescent waves into propagating waves for far-field super-resolution imaging. By detecting far-field intensity distributions of light through objects in front of the Fibonacci grating in free space, we can observe the objects with nearly λ/9 spatial resolution. Analytical results are verified by numerical simulations. We also discuss the effect of sampling error on imaging resolution of the system.

  5. Emergence of correlated optics in one-dimensional waveguides for classical and quantum atomic gases

    Science.gov (United States)

    Ruostekoski, Janne; Javanainen, Juha

    2016-09-01

    We analyze the emergence of correlated optical phenomena in the transmission of light through a waveguide that confines classical or ultracold quantum degenerate atomic ensembles. The conditions of the correlated collective response are identified in terms of atom density, thermal broadening, and photon losses by using stochastic Monte Carlo simulations and transfer matrix methods of transport theory. We also calculate the "cooperative Lamb shift" for the waveguide transmission resonance, and discuss line shifts that are specific to effectively one-dimensional waveguide systems.

  6. Quantum-chemical studies of quasi-one-dimensional electron systems. 1. Polyenes

    Directory of Open Access Journals (Sweden)

    Yuriy Kruglyak

    2015-05-01

    Full Text Available This review is devoted to the basic problem in quantum theory of quasi-one-dimensional electron systems like polyenes (Part 1 and cumulenes (Part 2 – physical origin of the forbidden zone in these and analogous 1D electron systems due to two possible effects – Peierls instability (bond alternation and Mott instability (electron correlation. Both possible contradiction and coexistence of the Mott and Peierls instabilities are summerized on the basis of the Kiev quantum chemistry team research projects.

  7. Entanglement in One-Dimensional Anderson Model with Long-Range Correlated Disorder

    Institute of Scientific and Technical Information of China (English)

    GUO Zi-Zheng

    2008-01-01

    @@ By using the measure of concurrence,the entanglement of the ground state in the one-dimensional Anderson model is studied with consideration of the long-range correlations. Three kinds of correlations are discussed.We compare the effects of the long-rang Gaussian and power-law correlations between the site energies on the concurrence,and demonstrate the existence of the band structure of the concurrence in the power-law case.

  8. Competition between spin and charge order in a one-dimensional lattice

    Science.gov (United States)

    Talebi, Amir Hossein; Davoudi, Bahman; Rahimitabar, M. Reza

    2017-10-01

    In this paper, we study the presence of competing instabilities in one-dimensional (1D) extended Hubbard model (EHM). Using the extended two-particle self-consistent approximation (ETPSC), we derive the density and interaction dependent crossover diagram for spin and charge density wave fluctuations at arbitrary wave number. We determine the phase transitions of the system by means of spin and charge susceptibilities. We draw the phase diagram which separates different phases of the model for several effective particle densities.

  9. Impurity-induced local modes in one-dimensional dusty plasma chains

    Institute of Scientific and Technical Information of China (English)

    Ren Yong-Chao; Wang Xin-Shang; Wang Xiao-Gang

    2012-01-01

    The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied.It is found that local modes can be excited besides lattice waves,due to the existence of an impurity particle.The dispersion relations of the modes are derived accordingly.Properties of the lattice and local modes are also analyzed and discussed,particularly for their symmetric features and conditions of the mode excitation.

  10. Fabrication and sensing behavior of one-dimensional ZnO-Zn2GeO4 heterostructures

    OpenAIRE

    Liang, Yuan-Chang; Lin, Tzu-Yin

    2014-01-01

    Well-crystalline one-dimensional ZnO-Zn2GeO4 (ZGO) heterostructures were successfully synthesized using a high-temperature solid-state reaction between the ZnO and Ge layers of ZnO-Ge core-shell nanostructures. The polycrystalline ZGO crystallites had a thickness in the range of 17 to 26 nm. The high-temperature solid-state reaction induced grooves and crystal defects on the surfaces of the ZGO crystallites. The sensors made from the ZnO-ZGO heterostructures exhibited a marked photocurrent re...

  11. Spin transfer torque effects in magnetic nanostructures

    Science.gov (United States)

    Chen, Tingyong

    Spin transfer torque (STT) effects have been studied using a point-contact spin injection technique in (1) magnetic trilayers, (2) a single exchange-biased ferromagnetic layer, and (3) magnetic granular solids. In the point-contact spin injection, a sharp metallic tip is in contact with a thin film structure. The high current density (e.g. 10 8 A/cm²) required for the STT effects is achieved by concentrating a current of a few milli-amperes into a point contact with a cross section less than 100 nanometers. Spin (polarized electrons) is injected into the contact region via a spin polarizer, a ferromagnetic film underneath the film structure. Resistance and differential resistance of the contact as a function of the current in the contact are measured at the same time using a lock-in technique. Steps in the resistance and spikes in the differential resistance indicate non-collinear spin structures are induced by the STT effect. The non-collinear spin structures are verified by the magnetoresistance of the contact with a small current without causing any STT effect. The experiments are carried out at cryogenic temperatures obtained by a liquid helium dewar and in magnetic fields up to 9 Tesla provided by a superconductor magnet. In magnetic trilayers such as Co/Cu/Co film where the STT effect is an inverse effect of the giant magnetoresistance (GMR) effect, a magnetic bit can be reversibly written by a spin polarized current injected through a point contact into the continuous film. The magnetic states written depend on the polarity of the injection currents, and remain stable at room temperature. The reversible writing can be achieved for a wide range of contact resistances with a well-defined voltage for the reversal. With the assistance of the exchange coupling of an antiferromagnetic CoO layer, a nanodomain has been created and manipulated by the inhomogeneous current density within a ferromagnetic Co layer, showing hysteretic switching loops at low fields. At

  12. A refined one-dimensional rotordynamics model with three-dimensional capabilities

    Science.gov (United States)

    Carrera, E.; Filippi, M.

    2016-03-01

    This paper evaluates the vibration characteristics of various rotating structures. The present methodology exploits the one-dimensional Carrera Unified Formulation (1D CUF), which enables one to go beyond the kinematic assumptions of classical beam theories. According to the component-wise (CW) approach, Lagrange-like polynomial expansions (LE) are here adopted to develop the refined displacement theories. The LE elements make it possible to model each structural component of the rotor with an arbitrary degree of accuracy using either different displacement theories or localized mesh refinements. Hamilton's Principle is used to derive the governing equations, which are solved by the Finite Element Method. The CUF one-dimensional theory includes all the effects due to rotation, namely the Coriolis term, spin softening and geometrical stiffening. The numerical simulations have been performed considering a thin ring, discs and bladed-deformable shafts. The effects of the number and the position of the blades on the dynamic stability of the rotor have been evaluated. The results have been compared, when possible, with the 2D and 3D solutions that are available in the literature. CUF models appear very practical to investigate the dynamics of complex rotating structures since they provide 2D and quasi-3D results, while preserving the computational effectiveness of one-dimensional solutions.

  13. Study of ac hopping conductivity on one-dimensional nanometre systems

    Institute of Scientific and Technical Information of China (English)

    徐慧; 宋祎璞

    2002-01-01

    In this paper, we establish a one-dimensional random nanocrystalline chain model, we derive a new formula of ac electron-phonon-field conductance for electron tunnelling transfer in one-dimensional nanometre systems. By calculating the ac conductivity, the relationship between the electric field, temperature and conductivity is analysed, and the effect of crystalline grain size and distortion of interfacial atoms on the ac conductance is discussed. A characteristic of negative differential dependence of resistance and temperature in the low-temperature region for a nanometre system is found. The ac conductivity increases linearly with rising frequency of the electric field, and it tends to increase as the crystalline grain size increases and to decrease as the distorted degree of interfacial atoms increases.

  14. Ordering of small particles in one-dimensional coherent structures by time-periodic flows

    CERN Document Server

    Pushkin, Dmitri; Shevtsova, Valentina

    2011-01-01

    Small particles transported by a fluid medium do not necessarily have to follow the flow. We show that for a wide class of time-periodic incompressible flows inertial particles have a tendency to spontaneously align in one-dimensional dynamic coherent structures. This effect may take place for particles so small that often they would be expected to behave as passive tracers and be used in PIV measurement technique. We link the particle tendency to form one-dimensional structures to the nonlinear phenomenon of phase locking. We propose that this general mechanism is, in particular, responsible for the enigmatic formation of the `particle accumulation structures' discovered experimentally in thermocapillary flows more than a decade ago and unexplained until now.

  15. Polymer quantization in the Bogoliubov's regime for a homogeneous one-dimensional Bose-Einstein condensate

    CERN Document Server

    Castellanos, Elías; Hernández-Hernández, Héctor H; Santos, Elí

    2016-01-01

    In the present report we analyze the eventual modifications caused by the polymer quantization upon the ground state of a homogeneous one-dimensional Bose-Einstein condensate. We obtain the ground state energy of the corresponding N-body system and, consequently, the corresponding speed of sound, allowing us to explore the sensitivity of the system to corrections caused by the polymer quantization. The corrections arising from the polymer quantization can be improved for dense systems together with small values of the corresponding one-dimensional scattering length. However, these corrections remain constrained due to finite size effects of the system. The contributions of the polymer length scale to the properties of the ground state energy of the system allow us to explore, as a first approximation and when the Bogoliubov's formalism is valid, the sensitivity of this many-body system to traces caused by the discreteness of space suggested by the polymer quantization.

  16. Quasi-one-dimensional spin-orbit-coupled correlated insulator in a multinuclear coordinated organometallic crystal

    Science.gov (United States)

    Merino, J.; Jacko, A. C.; Khosla, A. L.; Powell, B. J.

    2016-11-01

    We show how quasi-one-dimensional correlated insulating states arise at two-thirds filling in organometallic multinuclear coordination complexes described by layered decorated honeycomb lattices. The interplay of spin-orbit coupling and electronic correlations leads to pseudospin-one moments arranged in weakly coupled chains with highly anisotropic exchange and a large trigonal splitting. We show that the in-plane exchange coupling is very different from the interlayer coupling; in particular the latter is much larger, despite the underlying hopping integrals being close to isotropic. Surprisingly, the effective dimensionality of the pseudospin model is strongly dependent on the strength of the electronic correlations: With increasing Hubbard U the pseudospin-one model becomes increasingly one dimensional, even though the crystal is almost isotropic. We predict that the trigonal splitting leads to a quantum phase transition from a Haldane phase to a topologically trivial phase as the relative strength of the spin-orbit coupling increases.

  17. Effect of Cr content on the nanostructural evolution of irradiated ferritic/martensitic alloys: An object kinetic Monte Carlo model

    Energy Technology Data Exchange (ETDEWEB)

    Chiapetto, M., E-mail: mchiapet@sckcen.be [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d' Ascq Cedex (France); Malerba, L. [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Becquart, C.S. [Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d' Ascq Cedex (France)

    2015-10-15

    Self-interstitial cluster diffusivity in Fe–Cr alloys, model materials for high-Cr ferritic/martensitic steels, is known to be reduced in a non-monotonic way as a function of Cr concentration: it first decreases, then increases. This non-monotonic behaviour is caused by a relatively long-ranged attractive interaction between Cr atoms and crowdions and correlates well with the experimentally observed swelling in these alloys under neutron irradiation, also seen to first decrease and then increase with increasing Cr content, under comparable irradiation conditions. Moreover, recent studies reveal that C atoms dispersed in the Fe matrix form under irradiation complexes with vacancies which, in turn, act as trap for one-dimensionally migrating self-interstitial clusters. The mobility of one-dimensional migrating clusters is considered key to determine swelling susceptibility. However, no model has ever been built that quantitatively describes the dependence of swelling on Cr content, allowing for the presence of C in the matrix. In this work we developed physically-based sets of parameters for object kinetic Monte Carlo (OKMC) simulations intended to study the nanostructure evolution under irradiation in Fe–Cr–C alloys. The nanostructural evolution in Fe–C and in four Fe–Cr–C alloys (containing 2.5, 5, 9 and 12 wt.% Cr) neutron irradiated up to ∼0.6 dpa at 563 K was simulated according to the model and reference experiments were reproduced. Our model shows that the SIA cluster reduced mobility has a major influence on the nanostructural evolution: it increases the number of vacancy-SIA recombinations and thus leads to the suppression of voids formation. This provides a clear framework to interpret the non-monotonic dependence of swelling in Fe–Cr alloys versus Cr content. Our model also suggests that the amount of C in the matrix has an equally important role: high amounts of it may counteract the beneficial effect that Cr has in reducing swelling.

  18. Exceptional performance of TiNb₂O₇ anode in all one-dimensional architecture by electrospinning.

    Science.gov (United States)

    Jayaraman, Sundaramurthy; Aravindan, Vanchiappan; Suresh Kumar, Palaniswamy; Chui Ling, Wong; Ramakrishna, Seeram; Madhavi, Srinivasan

    2014-06-11

    We report the extraordinary performance of an Li-ion battery (full-cell) constructed from one-dimensional nanostructured materials, i.e. nanofibers as cathode, anode, and separator-cum-electrolyte, by scalable electrospinning. Before constructing such a one-dimensional Li-ion battery, electrospun materials are individually characterized to ensure its performance and balancing the mass loading as well. The insertion type anode TiNb2O7 exhibits the reversible capacity of ∼271 mAh g(-1) at current density of 150 mA g(-1) with capacity retention of ∼82% after 100 cycles. Under the same current density, electrospun LiMn2O4 cathode delivered the discharge capacity of ∼118 mAh g(-1). Gelled electrospun polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) nanofibers membrane is used as the separator-cum-electrolyte in both half-cell and full-cell assembly which exhibit the liquid like conductivity of ∼2.9 mS cm(-1) at ambient conditions. Full-cell, LiMn2O4|gelled PVdF-HFP|TiNb2O7 is constructed by optimized mass loading of cathode with respect to anode and tested between 1.95 and 2.75 V at room temperature. The full-cell delivered the reversible capacity of ∼116 mAh g(-1) at current density of 150 mA g(-1) with operating potential and energy density of ∼2.4 V and ∼278 Wh kg(-1), respectively. Further, excellent cyclability is noted for such configuration irrespective of the applied current densities.

  19. One-dimensional consolidation in unsaturated soils under cyclic loading

    Science.gov (United States)

    Lo, Wei-Cheng; Sposito, Garrison; Lee, Jhe-Wei; Chu, Hsiuhua

    2016-05-01

    The one-dimensional consolidation model of poroelasticity of Lo et al. (2014) for an unsaturated soil under constant loading is generalized to include an arbitrary time-dependent loading. A closed-form solution for the pore water and air pressures along with the total settlement is derived by employing a Fourier series representation in the spatial domain and a Laplace transformation in the time domain. This solution is illustrated for the important example of a fully-permeable soil cylinder with an undrained initial condition acted upon by a periodic stress. Our results indicate that, in terms of a dimensionless time scale, the transient solution decays to zero most slowly in a water-saturated soil, whereas for an unsaturated soil, the time for the transient solution to die out is inversely proportional to the initial water saturation. The generalization presented here shows that the diffusion time scale for pore water in an unsaturated soil is orders of magnitude greater than that in a water-saturated soil, mainly because of the much smaller hydraulic conductivity of the former.

  20. Integral Transport Theory in One-dimensional Geometries

    Energy Technology Data Exchange (ETDEWEB)

    Carlvik, I.

    1966-06-15

    A method called DIT (Discrete Integral Transport) has been developed for the numerical solution of the transport equation in one-dimensional systems. The characteristic features of the method are Gaussian integration over the coordinate as described by Kobayashi and Nishihara, and a particular scheme for the calculation of matrix elements in annular and spherical geometry that has been used for collision probabilities in earlier Flurig programmes. The paper gives a general theory including such things as anisotropic scattering and multi-pole fluxes, and it gives a brief description of the Flurig scheme. Annular geometry is treated in some detail, and corresponding formulae are given for spherical and plane geometry. There are many similarities between DIT and the method of collision probabilities. DIT is in many cases faster, because for a certain accuracy in the fluxes DIT often needs fewer space points than the method of collision probabilities needs regions. Several computer codes using DIT, both one-group and multigroup, have been written. It is anticipated that experience gained in calculations with these codes will be reported in another paper.

  1. Controlled Growth of One-Dimensional Oxide Nanomaterials

    Institute of Scientific and Technical Information of China (English)

    Xiaosheng FANG; Lide ZHANG

    2006-01-01

    This article reviews the recent developments in the controlled growth of one-dimensional (1D) oxide nanomaterials, including ZnO, SnO2, In2O3, Ga2O3, SiOx, MgO, and Al2O3. The growth of 1D oxide nanomaterials was carried out in a simple chemical vapor transport and condensation system. This article will begin with a survey of nanotechnology and 1D nanomaterials achieved by many researchers, and then mainly discuss on the controlled growth of 1D oxide nanomaterials with their morphologies, sizes, compositions, and microstructures controlled by altering experimental parameters, such as the temperature at the source material and the substrate, temperature gradient in the tube furnace, the total reaction time, the heating rate of the furnace, the gas flow rate, and the starting material. Their roles in the formation of various morphologies are analyzed and discussed. Finally, this review will be concluded with personal perspectives on the future research directions of this area.

  2. Approximate Relativistic Solutions for One-Dimensional Cylindrical Coaxial Diode

    Institute of Scientific and Technical Information of China (English)

    曾正中; 刘国治; 邵浩

    2002-01-01

    Two approximate analytical relativistic solutions for one-dimensional, space-chargelimited cylindrical coaxial diode are derived and utilized to compose best-fitting approximate solutions. Comparison of the best-fitting solutions with the numerical one demonstrates an error of about 11% for cathode-inside arrangement and 12% in the cathode-outside case for ratios of larger to smaller electrode radius from 1.2 to 10 and a voltage above 0.5 MV up to 5 MV. With these solutions the diode lengths for critical self-magnetic bending and for the condition under which the parapotential model validates are calculated to be longer than 1 cm up to more than 100 cm depending on voltage, radial dimensions and electrode arrangement. The influence of ion flow from the anode on the relativistic electron-only solution is numerically computed, indicating an enhancement factor of total diode current of 1.85 to 4.19 related to voltage, radial dimension and electrode arrangement.

  3. Negativity spectrum of one-dimensional conformal field theories

    CERN Document Server

    Ruggiero, Paola; Calabrese, Pasquale

    2016-01-01

    The partial transpose $\\rho_A^{T_2}$ of the reduced density matrix $\\rho_A$ is the key object to quantify the entanglement in mixed states, in particular through the presence of negative eigenvalues in its spectrum. Here we derive analytically the distribution of the eigenvalues of $\\rho_A^{T_2}$, that we dub negativity spectrum, in the ground sate of gapless one-dimensional systems described by a Conformal Field Theory (CFT), focusing on the case of two adjacent intervals. We show that the negativity spectrum is universal and depends only on the central charge of the CFT, similarly to the entanglement spectrum. The precise form of the negativity spectrum depends on whether the two intervals are in a pure or mixed state, and in both cases, a dependence on the sign of the eigenvalues is found. This dependence is weak for bulk eigenvalues, whereas it is strong at the spectrum edges. We also investigate the scaling of the smallest (negative) and largest (positive) eigenvalues of $\\rho_A^{T_2}$. We check our resu...

  4. One-Dimensional Electron Transport Layers for Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Ujwal K. Thakur

    2017-04-01

    Full Text Available The electron diffusion length (Ln is smaller than the hole diffusion length (Lp in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D structures such as nanowires (NWs and nanotubes (NTs as electron transport layers (ETLs is a promising method of achieving high performance halide perovskite solar cells (HPSCs. ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs. This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells.

  5. Digital noise generators using one-dimensional chaotic maps

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Ñonthe, J. A; Palacios-Luengas, L.; Cruz-Irisson, M.; Vazquez Medina, R. [Instituto Politécnico Nacional, ESIME-Culhuacan, Santa Ana 1000, 04430, D.F. (Mexico); Díaz Méndez, J. A. [Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, Tonantzintla, Puebla (Mexico)

    2014-05-15

    This work shows how to improve the statistical distribution of signals produced by digital noise generators designed with one-dimensional (1-D) chaotic maps. It also shows that in a digital electronic design the piecewise linear chaotic maps (PWLCM) should be considered because they do not have stability islands in its chaotic behavior region, as it occurs in the case of the logistic map, which is commonly used to build noise generators. The design and implementation problems of the digital noise generators are analyzed and a solution is proposed. This solution relates the output of PWLCM, usually defined in the real numbers' domain, with a codebook of S elements, previously defined. The proposed solution scheme produces digital noise signals with a statistical distribution close to a uniform distribution. Finally, this work shows that it is possible to have control over the statistical distribution of the noise signal by selecting the control parameter of the PWLCM and using, as a design criterion, the bifurcation diagram.

  6. A Smart Colorful Supercapacitor with One Dimensional Photonic Crystals

    Science.gov (United States)

    Liu, Cihui; Liu, Xing; Xuan, Hongyun; Ren, Jiaoyu; Ge, Liqin

    2015-12-01

    To meet the pressing demands for portable and flexible equipment in contemporary society, developing flexible, lightweight, and sustainable supercapacitor systems with large power densities, long cycle life, and ease of strongly required. However, estimating the state-of-charge of existing supercapacitors is difficult, and thus their service life is limited. In this study, we fabricate a flexible color indicative supercapacitor device with mesoporous polyaniline (mPANI)/Poly(N-Isopropyl acrylamide-Graphene Oxide-Acrylic Acid) (P(NiPPAm-GO-AA)) one dimensional photonic crystals (1DPCs) as the electrode material through a low-cost, eco-friendly, and scalable fabrication process. We found that the state-of-charge could be monitored by the structural color oscillation due to the change in the photonic band gap position of the 1DPCs. The flexible 1DPCs supercapacitor is thin at 3 mm and exhibits good specific capacitance of 22.6 F g-1 with retention of 91.1% after 3,000 cycles. This study shows the application of the 1DPCs supercapacitor as a visual ultrathin power source. The technology may find many applications in future wearable electronics.

  7. One-Dimensional Electron Transport Layers for Perovskite Solar Cells

    Science.gov (United States)

    Thakur, Ujwal K.; Kisslinger, Ryan; Shankar, Karthik

    2017-01-01

    The electron diffusion length (Ln) is smaller than the hole diffusion length (Lp) in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as electron transport layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs) as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs). This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells. PMID:28468280

  8. A disorder-enhanced quasi-one-dimensional superconductor.

    Science.gov (United States)

    Petrović, A P; Ansermet, D; Chernyshov, D; Hoesch, M; Salloum, D; Gougeon, P; Potel, M; Boeri, L; Panagopoulos, C

    2016-01-01

    A powerful approach to analysing quantum systems with dimensionality d>1 involves adding a weak coupling to an array of one-dimensional (1D) chains. The resultant quasi-1D (q1D) systems can exhibit long-range order at low temperature, but are heavily influenced by interactions and disorder due to their large anisotropies. Real q1D materials are therefore ideal candidates not only to provoke, test and refine theories of strongly correlated matter, but also to search for unusual emergent electronic phases. Here we report the unprecedented enhancement of a superconducting instability by disorder in single crystals of Na2-δMo6Se6, a q1D superconductor comprising MoSe chains weakly coupled by Na atoms. We argue that disorder-enhanced Coulomb pair-breaking (which usually destroys superconductivity) may be averted due to a screened long-range Coulomb repulsion intrinsic to disordered q1D materials. Our results illustrate the capability of disorder to tune and induce new correlated electron physics in low-dimensional materials.

  9. Multi-symplectic, Lagrangian, one-dimensional gas dynamics

    Science.gov (United States)

    Webb, G. M.

    2015-05-01

    The equations of Lagrangian, ideal, one-dimensional, compressible gas dynamics are written in a multi-symplectic form using the Lagrangian mass coordinate m and time t as independent variables, and in which the Eulerian position of the fluid element x = x(m, t) is one of the dependent variables. This approach differs from the Eulerian, multi-symplectic approach using Clebsch variables. Lagrangian constraints are used to specify equations for xm, xt, and St consistent with the Lagrangian map, where S is the entropy of the gas. We require St = 0 corresponding to advection of the entropy S with the flow. We show that the Lagrangian Hamiltonian equations are related to the de Donder-Weyl multi-momentum formulation. The pullback conservation laws and the symplecticity conservation laws are discussed. The pullback conservation laws correspond to invariance of the action with respect to translations in time (energy conservation) and translations in m in Noether's theorem. The conservation law due to m-translation invariance gives rise to a novel nonlocal conservation law involving the Clebsch variable r used to impose ∂S(m, t)/∂t = 0. Translation invariance with respect to x in Noether's theorem is associated with momentum conservation. We obtain the Cartan-Poincaré form for the system, and use it to obtain a closed ideal of two-forms representing the equation system.

  10. A Smart Colorful Supercapacitor with One Dimensional Photonic Crystals.

    Science.gov (United States)

    Liu, Cihui; Liu, Xing; Xuan, Hongyun; Ren, Jiaoyu; Ge, Liqin

    2015-12-22

    To meet the pressing demands for portable and flexible equipment in contemporary society, developing flexible, lightweight, and sustainable supercapacitor systems with large power densities, long cycle life, and ease of strongly required. However, estimating the state-of-charge of existing supercapacitors is difficult, and thus their service life is limited. In this study, we fabricate a flexible color indicative supercapacitor device with mesoporous polyaniline (mPANI)/Poly(N-Isopropyl acrylamide-Graphene Oxide-Acrylic Acid) (P(NiPPAm-GO-AA)) one dimensional photonic crystals (1DPCs) as the electrode material through a low-cost, eco-friendly, and scalable fabrication process. We found that the state-of-charge could be monitored by the structural color oscillation due to the change in the photonic band gap position of the 1DPCs. The flexible 1DPCs supercapacitor is thin at 3 mm and exhibits good specific capacitance of 22.6 F g(-1) with retention of 91.1% after 3,000 cycles. This study shows the application of the 1DPCs supercapacitor as a visual ultrathin power source. The technology may find many applications in future wearable electronics.

  11. Transmission properties of one-dimensional ternary plasma photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shiveshwari, Laxmi [Department of Physics, K. B. Womens' s College, Hazaribagh 825 301 (India); Awasthi, S. K. [Department of Physics and Material Science and Engineering, Jaypee Institute of Information Technology, Noida 201 304 (India)

    2015-09-15

    Omnidirectional photonic band gaps (PBGs) are found in one-dimensional ternary plasma photonic crystals (PPC) composed of single negative metamaterials. The band characteristics and transmission properties are investigated through the transfer matrix method. We show that the proposed structure can trap light in three-dimensional space due to the elimination of Brewster's angle transmission resonance allowing the existence of complete PBG. The results are discussed in terms of incident angle, layer thickness, dielectric constant of the dielectric material, and number of unit cells (N) for TE and TM polarizations. It is seen that PBG characteristics is apparent even in an N ≥ 2 system, which is weakly sensitive to the incident angle and completely insensitive to the polarization. Finite PPC could be used for multichannel transmission filter without introducing any defect in the geometry. We show that the locations of the multichannel transmission peaks are in the allowed band of the infinite structure. The structure can work as a single or multichannel filter by varying the number of unit cells. Binary PPC can also work as a polarization sensitive tunable filter.

  12. Conjugated Molecules Described by a One-Dimensional Dirac Equation.

    Science.gov (United States)

    Ernzerhof, Matthias; Goyer, Francois

    2010-06-08

    Starting from the Hückel Hamiltonian of conjugated hydrocarbon chains (ethylene, allyl radical, butadiene, pentadienyl radical, hexatriene, etc.), we perform a simple unitary transformation and obtain a Dirac matrix Hamiltonian. Thus already small molecules are described exactly in terms of a discrete Dirac equation, the continuum limit of which yields a one-dimensional Dirac Hamiltonian. Augmenting this Hamiltonian with specially adapted boundary conditions, we find that all the orbitals of the unsaturated hydrocarbon chains are reproduced by the continuous Dirac equation. However, only orbital energies close to the highest occupied molecular orbital/lowest unoccupied molecular orbital energy are accurately predicted by the Dirac equation. Since it is known that a continuous Dirac equation describes the electronic structure of graphene around the Fermi energy, our findings answer the question to what extent this peculiar electronic structure is already developed in small molecules containing a delocalized π-electron system. We illustrate how the electronic structure of small polyenes carries over to a certain class of rectangular graphene sheets and eventually to graphene itself. Thus the peculiar electronic structure of graphene extends to a large degree to the smallest unsaturated molecule (ethylene).

  13. Validation and Comparison of One-Dimensional Graound Motion Methodologies

    Energy Technology Data Exchange (ETDEWEB)

    B. Darragh; W. Silva; N. Gregor

    2006-06-28

    Both point- and finite-source stochastic one-dimensional ground motion models, coupled to vertically propagating equivalent-linear shear-wave site response models are validated using an extensive set of strong motion data as part of the Yucca Mountain Project. The validation and comparison exercises are presented entirely in terms of 5% damped pseudo absolute response spectra. The study consists of a quantitative analyses involving modeling nineteen well-recorded earthquakes, M 5.6 to 7.4 at over 600 sites. The sites range in distance from about 1 to about 200 km in the western US (460 km for central-eastern US). In general, this validation demonstrates that the stochastic point- and finite-source models produce accurate predictions of strong ground motions over the range of 0 to 100 km and for magnitudes M 5.0 to 7.4. The stochastic finite-source model appears to be broadband, producing near zero bias from about 0.3 Hz (low frequency limit of the analyses) to the high frequency limit of the data (100 and 25 Hz for response and Fourier amplitude spectra, respectively).

  14. Fermion Coherent State Studies of One-Dimensional Hubbard Model

    Institute of Scientific and Technical Information of China (English)

    LIN Ji; GAO Xian-Long; WANG Ke-Lin

    2007-01-01

    We present a comparative study of the ground state of the one-dimensional Hubbard model. We first use a new fermion coherent state method in the framework of Fermi liquid theory by introducing a hole operator and considering the interactions of two pairs electrons and holes. We construct the ground state of the Hubbard model as |〉 = [f + ∑′ψc+k1σ1 h+k2σ2 c+k3σ3 h+k4σ4 ∏exp(ρc+k1σ1 h+k2σ2)] [〉0, where ψ and ρ are the coupling constants. Our results are then compared to those of variational methods, density functional theory based on the exact solvable Bethe ansatz solutions, variational Monto-Carlo method (VMC) as well as to the exact result of the infinite system. We find satisfactory agreement between the fermion coherent state scheme and the VMC data, and provide a new picture to deal with the strongly correlated system.

  15. Topological water wave states in a one-dimensional structure

    Science.gov (United States)

    Yang, Zhaoju; Gao, Fei; Zhang, Baile

    2016-01-01

    Topological concepts have been introduced into electronic, photonic, and phononic systems, but have not been studied in surface-water-wave systems. Here we study a one-dimensional periodic resonant surface-water-wave system and demonstrate its topological transition. By selecting three different water depths, we can construct different types of water waves - shallow, intermediate and deep water waves. The periodic surface-water-wave system consists of an array of cylindrical water tanks connected with narrow water channels. As the width of connecting channel varies, the band diagram undergoes a topological transition which can be further characterized by Zak phase. This topological transition holds true for shallow, intermediate and deep water waves. However, the interface state at the boundary separating two topologically distinct arrays of water tanks can exhibit different bands for shallow, intermediate and deep water waves. Our work studies for the first time topological properties of water wave systems, and paves the way to potential management of water waves. PMID:27373982

  16. Electron Rydberg wave packets in one-dimensional atoms

    Indian Academy of Sciences (India)

    Supriya Chatterjee; Amitava Choudhuri; Aparna Saha; B Talukdar

    2010-09-01

    An expression for the transition probability or form factor in one-dimensional Rydberg atom irradiated by short half-cycle pulse was constructed. In applicative contexts, our expression was found to be more useful than the corresponding result given by Landau and Lifshitz. Using the new expression for the form factor, the motion of a localized quantum wave packet was studied with particular emphasis on its revival and super-revival properties. Closed form analytical expressions were derived for expectation values of the position and momentum operators that characterized the widths of the position and momentum distributions. Transient phase-space localization of the wave packet produced by the application of a single impulsive kick was explicitly demonstrated. The undulation of the uncertainty product as a function of time was studied in order to visualize how the motion of the wave packet in its classical trajectory spreads throughout the orbit and the system becomes nonclassical. The process, however, repeats itself such that the atom undergoes a free evolution from a classical, to a nonclassical, and back to a classical state.

  17. One-dimensional Ising model with multispin interactions

    CERN Document Server

    Turban, L

    2016-01-01

    We study the spin-$1/2$ Ising chain with multispin interactions $K$ involving the product of $m$ successive spins, for general values of $m$. Using a change of spin variables the zero-field partition function of a finite chain is obtained for free and periodic boundary conditions (BC) and we calculate the two-spin correlation function. When placed in an external field $H$ the system is shown to be self-dual. Using another change of spin variables the one-dimensional (1D) Ising model with multispin interactions in a field is mapped onto a zero-field rectangular Ising model with first-neighbour interactions $K$ and $H$. The 2D system, with size $m\\times N/m$, has the topology of a cylinder with helical BC. In the thermodynamic limit $N/m\\to\\infty$, $m\\to\\infty$, a 2D critical singularity develops on the self-duality line, $\\sinh 2K\\sinh 2H=1$.

  18. One dimensional coordination polymers: Synthesis, crystal structures and spectroscopic properties

    Science.gov (United States)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Şahin, Onur

    2016-11-01

    Two new one dimensional (1D) cyanide complexes, namely [M(4-aepy)2(H2O)2][Pt(CN)4], (4-aepy = 4-(2-aminoethyl)pyridine M = Cu(II) (1) or Zn(II) (2)), have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal and elemental analyses techniques. The crystallographic analyses reveal that 1 and 2 are isomorphous and isostructural, and crystallize in the monoclinic system and C2 space group. The Pt(II) ions are coordinated by four cyanide-carbon atoms in the square-planar geometry and the [Pt(CN)4]2- ions act as a counter ion. The M(II) ions display an N4O2 coordination sphere with a distorted octahedral geometry, the nitrogen donors belonging to four molecules of the organic 4-aepy that act as unidentate ligands and two oxygen atoms from aqua ligands. The crystal structures of 1 and 2 are similar each other and linked via intermolecular hydrogen bonding, Pt⋯π interactions to form 3D supramolecular network. Vibration assignments of all the observed bands are given and the spectral features also supported to the crystal structures of the complexes.

  19. A one-dimensional theory for Higgs branch operators

    CERN Document Server

    Dedushenko, Mykola; Yacoby, Ran

    2016-01-01

    We use supersymmetric localization to calculate correlation functions of half-BPS local operators in 3d ${\\cal N} = 4$ superconformal field theories whose Lagrangian descriptions consist of vectormultiplets coupled to hypermultiplets. The operators we primarily study are certain twisted linear combinations of Higgs branch operators that can be inserted anywhere along a given line. These operators are constructed from the hypermultiplet scalars. They form a one-dimensional non-commutative operator algebra with topological correlation functions. The 2- and 3-point functions of Higgs branch operators in the full 3d ${\\cal N}=4$ theory can be simply inferred from the 1d topological algebra. After conformally mapping the 3d superconformal field theory from flat space to a round three-sphere, we preform supersymmetric localization using a supercharge that does not belong to any 3d ${\\cal N} = 2$ subalgebra of the ${\\cal N}=4$ algebra. The result is a simple model that can be used to calculate correlation functions ...

  20. Mesoscopic spin Hall effect in semiconductor nanostructures

    Science.gov (United States)

    Zarbo, Liviu

    The spin Hall effect (SHE) is a name given to a collection of diverse phenomena which share two principal features: (i) longitudinal electric current flowing through a paramagnetic semiconductor or metallic sample leads to transverse spin current and spin accumulation of opposite sign at opposing lateral edges; (ii) SHE does not require externally applied magnetic field or magnetic ordering in the equilibrium state of the sample, instead it relies on the presence of spin-orbit (SO) couplings within the sample. This thesis elaborates on a new type of phenomenon within the SHE family, predicted in our recent studies [Phys. Rev. B 72, 075361 (2005); Phys. Rev. Lett. 95, 046601 (2005); Phys. Rev. B 72, 075335 (2005); Phys. Rev. B 73 , 075303 (2006); and Europhys. Lett. 77, 47004 (2007)], where pure spin current flows through the transverse electrodes attached to a clean finitesize two-dimensional electron gas (2DEG) due to unpolarized charge current injected through its longitudinal leads. If transverse leads are removed, the effect manifests as nonequilibrium spin Hall accumulation at the lateral edges of 2DEG wires. The SO coupling driving this SHE effect is of the Rashba type, which arises due to structural inversion asymmetry of semiconductor heterostructure hosting the 2DEG. We term the effect "mesoscopic" because the spin Hall currents and accumulations reach optimal value in samples of the size of the spin precession length---the distance over which the spin of an electron precesses by an angle pi. In strongly SO-coupled structures this scale is of the order of ˜100 nm, and, therefore, mesoscopic in the sense of being much larger than the characteristic microscopic scales (such as the Fermi wavelength, screening length, or the mean free path in disordered systems), but still much smaller than the macroscopic ones. Although the first theoretical proposal for SHE, driven by asymmetry in SO-dependent scattering of spin-up and spin-down electrons off impurities