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Nano Letters

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https://www.readbyqxmd.com/read/30016115/near-field-thermophotonic-systems-for-low-grade-waste-heat-recovery
#1
Bo Zhao, Parthiban Santhanam, Kaifeng Chen, Siddharth Buddhiraju, Shanhui Fan
Low-grade waste heat contains an enormous amount of exergy that can be recovered for renewable energy generation. Current solid-state techniques for recovering low-grade waste heat, such as thermoelectric generators and thermophotovoltaics, however, are limited by low conversion efficiencies or power densities. In this work, we propose a solid-state near-field thermophotonic system. The system consists of a light emitting diode (LED) on the hot side and a photovoltaic (PV) cell on the cold side. Part of the generated power by the PV cell is used to positively bias the LED...
July 17, 2018: Nano Letters
https://www.readbyqxmd.com/read/30016110/two-photon-microscopy-with-a-double-wavelength-metasurface-objective-lens
#2
Ehsan Arbabi, Jiaqi Li, Romanus J Hutchins, Seyedeh Mahsa Kamali, Amir Arbabi, Yu Horie, Pol Van Dorpe, Viviana Gradinaru, Daniel A Wagenaar, Andrei Faraon
Two-photon microscopy is a key imaging technique in life sciences due to its superior deep-tissue imaging capabilities. Light-weight and compact two-photon microscopes are of great interest because of their applications for in vivo deep brain imaging. Recently, dielectric metasurfaces have enabled a new category of small and light-weight optical elements, including objective lenses. Here we experimentally demonstrate two-photon microscopy using a double-wavelength metasurface lens. It is specifically designed to focus 820-nm and 605-nm light, corresponding to the excitation and emission wavelengths of the measured fluorophors, to the same focal distance...
July 17, 2018: Nano Letters
https://www.readbyqxmd.com/read/30016109/multiexciton-lifetimes-reveal-triexciton-emission-pathway-in-cdse-nanocrystals
#3
Katherine E Shulenberger, Thomas S Bischof, Justin R Caram, Hendrik Utzat, Igor Coropceanu, Lea Nienhaus, Moungi G Bawendi
Multiexcitons in emerging semiconducting nanomaterials play a critical role in potential optoelectronic and quantum computational devices. We describe photon resolved single molecule methods to directly probe the dynamics of biexcitons and triexcitons in colloidal CdSe quantum dots. We confirm that biexcitons emit from a spin-correlated state, consistent with statistical scaling. Contrary to current understanding, we find that triexciton emission is dominated by band-edge 1Se 1S3/2 recombination rather than the higher energy 1Pe 1P3/2 recombination...
July 17, 2018: Nano Letters
https://www.readbyqxmd.com/read/30014701/correction-to-ga-doped-pt-ni-octahedral-nanoparticles-as-a-highly-active-and-durable-electrocatalyst-for-oxygen-reduction-reaction
#4
JeongHoon Lim, Hyeyoung Shin, MinJoong Kim, Hoin Lee, Kug-Seung Lee, YongKeun Kwon, DongHoon Song, SeKwon Oh, Hyungjun Kim, EunAe Cho
No abstract text is available yet for this article.
July 17, 2018: Nano Letters
https://www.readbyqxmd.com/read/30011211/synthesis-of-silver-nanowires-with-reduced-diameters-using-benzoin-derived-radicals-to-make-transparent-conductors-with-high-transparency-and-low-haze
#5
Zhiqiang Niu, Fan Cui, Elisabeth Kuttner, Chenlu Xie, Hong Chen, Yuchun Sun, Ahmad Dehestani, Kerstin Schierle-Arndt, Peidong Yang
Reducing the diameter of silver nanowires has been proven an effective way to improve their optoelectronic performance by lessening light attenuation. The state-of-the-art silver nanowires are typically around 20 nm in diameter. Herein we report a modified polyol synthesis of silver nanowires with average diameters as thin as 13 nm, and aspect ratios up to 3000. The success of this synthesis is based on the employment of benzoin-derived radicals in the polyol approach and does not require high-pressure conditions...
July 16, 2018: Nano Letters
https://www.readbyqxmd.com/read/30011210/stable-ultralow-threshold-amplified-spontaneous-emission-from-cspbbr3-nanoparticles-exhibiting-trion-gain
#6
Yi Wang, Min Zhi, Yu Qiang Chang, Jian-Ping Zhang, Yinthai Chan
Wet-chemically synthesized cesium lead halide nanoparticles have many attractive properties that make them promising as optical gain media, but generally suffer from poor stability under ambient conditions and an optical gain threshold that is widely believed to be dictated by the need for biexcitons. These conditions make it impractical for such particles to be utilized as gain media given the need to undergo repeated stimulated emission processes at above-threshold pump intensities over long periods of time...
July 16, 2018: Nano Letters
https://www.readbyqxmd.com/read/30005162/reversible-assembly-and-dynamic-plasmonic-tuning-of-ag-nanoparticles-enabled-by-limited-ligand-protection
#7
Luntao Liu, Zongpeng Gao, Baolai Jiang, Yaocai Bai, Wenshou Wang, Yadong Yin
Dynamic manipulation of optical property through the reversible assembly of plasmonic nanoparticles offers great opportunities for practical applications in many fields. The previous success, however, has been limited to Au nanoparticles. Reversible assembly and plasmonic tuning of Ag nanoparticles (AgNPs) have remained a significant challenge due to the difficulty in finding an appropriate surface agent that can effectively stabilize the particle surface and control their interactions. Here we overcome the challenge by developing a limited-ligand-protection (LLP) strategy for introducing polyacrylic acid with precisely controlled coverage to AgNP surface to not only sufficiently stabilize the nanoparticles but also enable effective control over the surface charge and particle interaction through pH variation...
July 13, 2018: Nano Letters
https://www.readbyqxmd.com/read/30005161/internal-nanostructure-diagnosis-with-hyperbolic-phonon-polaritons-in-hexagonal-boron-nitride
#8
Siyuan Dai, Mykhailo Tymchenko, Zai-Quan Xu, Toan Trong Tran, Yafang Yang, Qiong Ma, Kenji Watanabe, Takashi Taniguchi, Pablo Jarillo-Herrero, Igor Aharonovich, Dimitri N Basov, Tiger Tao, Andrea Alu
Imaging materials and inner structures with resolution below the diffraction limit has become of fundamental importance in recent years for a wide variety of applications. In this work, we report sub-diffractive internal structure diagnosis of hexagonal boron nitride by exciting and imaging hyperbolic phonon polaritons. Based on their unique propagation properties, we are able to accurately locate defects in the crystal interior with nanometer resolution. The precise location, size and geometry of the concealed defects is reconstructed by analyzing the polariton wavelength, reflection coefficient and their dispersion...
July 13, 2018: Nano Letters
https://www.readbyqxmd.com/read/30004715/microscale-resolution-thermal-mapping-using-a-flexible-platform-of-patterned-quantum-sensors
#9
Paolo Andrich, Jiajing Li, Xiaoying Liu, F Joseph Heremans, Paul F Nealey, David Awschalom
Temperature sensors with micro- and nanoscale spatial resolution have long been explored for their potential to investigate the details of physical systems at an unprecedented scale. In particular, the rapid miniaturization of transistor technology, with the associated steep boost in power density, calls for sensors that accurately monitor heating distributions. Here, we report on a simple and scalable fabrication approach, based on directed self-assembly and transfer printing techniques, to construct arrays of nanodiamonds containing temperature sensitive fluorescent spin defects...
July 13, 2018: Nano Letters
https://www.readbyqxmd.com/read/30004712/three-dimensional-composition-and-electric-potential-mapping-of-iii-v-core-multishell-nanowires-by-correlative-stem-and-holographic-tomography
#10
Daniel Wolf, René Hübner, Tore Niermann, Sebastian Sturm, Paola Prete, Nicola Lovergine, Bernd Buechner, Axel Lubk
The non-destructive characterization of nanoscale devices, such as those based on semiconductor nanowires, in terms of functional potentials is crucial for correlating device properties with their morphological/materials features, as well as for precisely tuning and optimizing their growth process. Electron Holographic Tomography (EHT) has been used in the past to reconstruct the total potential distribution in 3D but hitherto lacked a quantitative approach to separate potential variations due to chemical composition changes (mean inner potential - MIP) and space charges...
July 13, 2018: Nano Letters
https://www.readbyqxmd.com/read/30001492/resolving-mixtures-in-solution-by-single-molecule-rotational-diffusivity
#11
Hsiang-Yu Yang, William Esco Moerner
Sensing the size of individual molecules in an ensemble has proven to be a powerful tool to investigate biomolecular interactions and association-dissociation processes. In biologically-relevant solution environments, molecular size is often sensed by translational or rotational diffusivity. The rotational diffusivity is more sensitive to the size and conformation of the molecules as it is inversely proportional to the cube of the hydrodynamic radius, as opposed to the inverse linear dependence of the translational diffusion coefficient...
July 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/30001486/exploring-the-magnetic-and-electric-side-of-light-through-plasmonic-nanocavities
#12
Cyrine Ernandes, Hung-Ju Lin, Michel Mortier, Patrick Gredin, Mathieu Mivelle, Lionel Aigouy
Light-matter interactions are often considered to be mediated by the electric component of light only, neglecting the magnetic contribution. However, the electromagnetic energy density is equally distributed between both parts of the optical fields. Within this scope, we experimentally demonstrate here, in excellent agreement with numerical simulations, that plasmonic nanostructures can selectively manipulate and tune the magnetic versus electric emission of luminescent nanocrystals. In particular, we show selective enhancement or decay of magnetic and electric emission from trivalent europium-doped nanoparticles in the vicinity of plasmonic nanocavities, designed to efficiently couple to either the electric or magnetic emission of the quantum emitter...
July 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/30001140/orientational-epitaxy-of-van-der-waals-molecular-heterostructures
#13
Luan Guo, Yitao Wang, Dogan Kaya, Richard E Palmer, GuangDe Chen, Quanmin Guo
The shape of individual building blocks is an important parameter in bottom-up self-assembly of nanostructured materials. A simple shape change from sphere to spheroid can significantly affect the assembly process due to the modification to the orientational degrees of freedom. When a layer of spheres is placed upon a layer of spheroids, the strain at the interface can be minimised by the spheroid taking a special orientation. C70 fullerenes represent the smallest spheroids and their interaction with a sphere-like C60 is investigated...
July 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/30001138/nanowires-for-biosensing-lightguiding-of-fluorescence-as-a-function-of-diameter-and-wavelength
#14
Damiano Verardo, Frida Wilhelmina Lindberg, Nicklas Anttu, Cassandra S Niman, Mercy Lard, Aleksandra P Dabkowska, Tommy Nylander, Alf Mansson, Christelle Prinz, Heiner Linke
Semiconductor nanowires can act as nanoscaled optical fibers, enabling them to guide and concentrate light emitted by surface-bound fluorophores, potentially enhancing the sensitivity of optical biosensing. While parameters such as the nanowire geometry and the fluorophore wavelength can be expected to strongly influence this lightguiding effect, no detailed description of their effect on in-coupling of fluorescent emission is available to date. Here, we use confocal imaging to quantify the lightguiding effect in GaP nanowires as a function of nanowire geometry and light wavelength...
July 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/30001136/semiconducting-van-der-waals-interfaces-as-artificial-semiconductors
#15
Evgeniy Ponomarev, Nicolas Ubrig, Ignacio Gutiérrez-Lezama, Helmuth Berger, Alberto F Morpurgo
Recent technical progress is demonstrating the possibility to stack together virtually any combination of atomically thin crystals of van der Waals bonded compounds to form new types of heterostructures and interfaces. As a result, there is the need to understand at a quantitative level how the interfacial properties are determined by the properties of the constituent 2D materials. We address this problem by studying the transport and opto-electronic response of two different interfaces based on transition metal dichalcogenide monolayers, namely WSe2 /MoSe2 and WSe2 /MoS2 ...
July 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/30001134/one-million-percent-tunnel-magnetoresistance-in-a-magnetic-van-der-waals-heterostructure
#16
Hyun Ho Kim, Bowen Yang, Tarun Patel, Francois Sfigakis, Chenghe Li, Shangjie Tian, Hechang Lei, Adam Tsen
We report the observation of a very large negative magnetoresistance effect in a van der Waals tunnel junction incorporating a thin magnetic semiconductor, CrI3, as the active layer. At constant voltage bias, current increases by nearly one million percent upon application of a 2 Tesla field. The effect arises from a change between antiparallel to parallel alignment of spins across the different CrI3 layers. Our results elucidate the nature of the magnetic state in ultrathin CrI3 and present new opportunities for spintronics based on two-dimensional materials...
July 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/29998736/photoactivated-specific-mrna-detection-in-single-living-cells-by-coupling-signal-on-fluorescence-and-signal-off-electrochemical-signals
#17
Fujian Huang, Meihua Lin, Ruilin Duan, Xiaoding Lou, Fan Xia, Itamar Willner
The spatiotemporal detection of a target mRNA in a single living cell is a major challenge in nanoscience and nanomedicine. We introduce a versatile method to detect mRNA at a single living cell level that uses photocleavable hairpin probes as functional units for the optical (fluorescent) and electrochemical (voltammetric) detection of MnSOD mRNA in single MCF-7 cancer cells. The fluorescent probe is composed of an ortho-nitrophenylphosphate ester functionalized hairpin that includes the FAM fluorophore in a caged configuration quenched by Dabcyl...
July 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/29998735/observation-of-gap-opening-in-1t-phase-mos2-nanocrystals
#18
Hai Xu, Dong Han, Yang Bao, Fang Cheng, Zijing Ding, Sherman Jun Rong Tan, Kian Ping Loh
Two dimensional (2D) transition metal dichalcogenides (TMDs) manifest in various pol-ymorphs which deliver different electronic properties; the most prominent among them include the semiconducting 2H phase and metallic 1T (or distorted 1T' phase) phase. Alkali metal in-tercalation or interface strain has been used to induce semiconductor-to-metal transition in monolayer MoS2 sheet, leading to exotic quantum states or improved performance in catalysis. However, the direct growth of 1T or 1T' phase MoS2 is challenging due to its metastability...
July 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/29996060/strong-spatial-and-spectral-localization-of-surface-plasmons-in-individual-randomly-disordered-gold-nanosponges
#19
Jin-Hui Zhong, Abbas Chimeh, Anke Korte, Felix Schwarz, Jue-Min Yi, Dong Wang, Jinxin Zhan, Peter Schaaf, Erich Runge, Christoph Lienau
Porous nanosponges, percolated with a three-dimensional network of 10-nm sized ligaments, recently emerged as promising substrates for plasmon-enhanced spectroscopy and (photo-)catalysis. Experimental and theoretical work suggests surface plasmon localization in some hot-spot modes as the physical origin of their unusual optical properties, but so far the existence of such hot-spots has not been proven. Here we use scattering-type scanning near-field nano-spectroscopy on individual gold nanosponges to reveal spatially and spectrally confined modes at 10 nanometer scale by recording local near-field scattering spectra...
July 11, 2018: Nano Letters
https://www.readbyqxmd.com/read/29995430/ultrascaled-germanium-nanowires-for-highly-sensitive-photodetection-at-the-quantum-ballistic-limit
#20
Philipp Staudinger, Masiar Sistani, Johannes Greil, Emmerich Bertagnolli, Alois Lugstein
We report an experimental study on quasi-one-dimensional Al-Ge-Al nanowire (NW) heterostructures featuring unmatched photoconductive gains exceeding 10^7 and responsivities as high as 10 A/µW in the visible wavelength regime. Our observations are attributed to the presence of GeOx related hole-trapping states at the NW surface and can be described by a photogating effect in accordance with previous studies on low-dimensional nanostructures. Utilizing an ultrascaled photodetector device operating in the quantum ballistic transport regime at room temperature we demonstrate for the first time that individual current channels can be addressed directly by laser irradiation...
July 11, 2018: Nano Letters
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