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- 2018
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- periodic paperclip-shaped structure
- antenna array
- mutual coupling reduction
- Bessel Function
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- Fusion temperature and Elongation speed
- Electronic Science and Technology
- Physics
- UIN Suska Riau
- Xi'an University of the Science and Technology
- University of Riau
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Combination of OPSY and PhD-PHIP results in enhanced sensitivity in PHIP
摘要： Despite the large degree of polarization in PHIP experiments compared to the Boltzmann factor, the presence of a large amount of non-reacted molecules with thermal polarization is an important obstacle when dealing with very diluted samples. The feasibility of enhancing both sensitivity and resolution in a single experiment by combining two well established pulse sequences, OPSY and PHD-PHIP is presented. OPSY is used as a block for filtering the signals originated from thermally polarized protons. PhD-PHIP, on the other hand, is used as an acquisition block, increasing the resolution and further improving the sensitivity by preventing signal canceling in the presence of magnetic field inhomogeneities. Experiments in a complex sample with very low hyperpolarization levels are presented showing the excellent performance of the method.
关键词： Echo trains,PhD-PHIP,Spin dynamics,CPMG,J-spectroscopy,Hyperpolarization,Pulse sequences,Parahydrogen,SABRE,J-coupling,NMR,OPSY,PHIP
更新于2025-09-23 15:23:52
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Production of a Scalar Boson and a Heavy Fermion Pair in Counterpropagating Е–Е+ Beams
摘要： The process of production of an HSM scalar boson of the Standard Model (H and h bosons of the Minimal Supersymmetric Standard Model) and a heavy fermion pair tt in counterpropagating electron-positron beams e+ e- -> H tt (e+ e- -> h tt) is discussed. Analytical expressions for the energy spectrum of the Higgs boson and the transverse spin asymmetry and the right-left spin asymmetry are obtained, and their dependences on the emission angle and energy of the Higgs boson are investigated.
关键词： left and right coupling constants,heavy fermion pair,Standard Model,Minimal Supersymmetric Standard Model,Weinberg parameter
更新于2025-09-23 15:23:52
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2D Schottky Junction between Graphene Oxide and Transition-Metal Dichalcogenides: Photoresponsive Properties and Electrocatalytic Performance
摘要： 2D graphene is conductor and not a semiconductor. 2D transition—metal dichalcogenides (TMD) is a semiconductor and not a conductor. Preparing 2D composite material that simultaneously possesses both advantages of graphene and TMD has proven to be challenging. In this work, both 2D-WS2/2D-GO and 2D-MoS2/2D-GO composites with few layer thickness are synthesized. The electronic structure indicates a high content of Mo4+ 3d5/2 and W4+4f7/2 with lower binding energy in the 2D composite, which is ascribed to partial loss of surface sulfur atoms in 2D composites and the newly formed heteroatomic bond of CWS and CMoS. The Schottky junction between 2D-GO and 2D-TMD (2D G-T junction) is established and exhibits obvious photoelectric responses. Superior electrocatalytic properties of the two 2D-composites are attributable to the 2D Schottky Junction between 2D-TMDs and 2D-GO. Interlayer electronic coupling in 2D Schottky Junction (2D G-T junction) activates inert sites on the 2D surface of 2D-TMDs or GO. The power conversion efficiency of dye-sensitized solar cells (DSCs) based on 2D-WS2/2D-GO is 9.54% under standard solar illumination intensity (AM1.5, 100 mW cm?2). The value is one of the highest reported efficiencies for DSCs based on Pt-free counter electrodes. Finally, 2D-WS2/2D-GO composites exhibit excellent stability as counter electrode of DSCs.
关键词： photoresponse,interlayer electronic coupling,2D,electrocatalyst,graphene,transition-metal dichalcogenides,Schottky junction
更新于2025-09-23 15:23:52
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Two-dimensional amorphous heterostructures of Ag/a-WO3- for high-efficiency photocatalytic performance
摘要： Synergistic photocatalysis is an important concept for designing the high-efficiency catalysis for fundamental research and technical applications. In this study a well-defined synergistic photocatalysis system is realized by the 2D amorphous heterostructures (2DAHs) Ag/a-WO3-x, which are constructed by Ag nanoparticles on 2D amorphous tungsten oxide (a-WO3-x) fabricated via supercritical CO2 method. We demonstrate theoretically that the oxygen evolution reactions (OER), characterized by photocurrent response, have been dramatically improved in Ag/a-WO3-x than those of both single a-WO3-x and Ag/WO3 systems. Such an enhanced photoelectrochemical performance attributes to the superposition effect of amorphous effect catalysis and local surface plasmon resonances (LSPR) catalysis. More interestingly, the ab initio density-functional theory calculations reveal that the amorphous effect catalysis ascribes to the unique d-d tail states coupling of both Ag and W atoms in the 2DAHs. Overall, our findings not only propose the prototype of synergistic photocatalysis, but also provide a new methodology to the design of novel catalyst.
关键词： 2D amorphous tungsten oxide,amorphous effect catalysis,synergistic photocatalysis,d-d tail states coupling,2D amorphous heterostructures Ag/a-WO3-x
更新于2025-09-23 15:23:52
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Lateral interfaces of transition metal dichalcogenides: A stable tunable one-dimensional physics platform
摘要： We study in-plane lateral heterostructures of commensurate transition-metal dichalcogenides, such as MoS2-WS2 and MoSe2-WSe2, and find interfacial and edge states that are highly localized to these regions of the heterostructure. These are one-dimensional (1D) in nature, lying within the band gap of the bulk structure and exhibiting complex orbital and spin structure. We describe such heteroribbons with a three-orbital tight-binding model that uses first principles and experimental parameters as input, allowing us to model realistic systems. Analytical modeling for the 1D interfacial bands results in long-range hoppings due to the hybridization along the interface, with strong spin-orbit couplings. We further explore the Ruderman-Kittel-Kasuya-Yosida indirect interaction between magnetic impurities located at the interface. The unusual features of the interface states result in effective long-range exchange noncollinear interactions between impurities. These results suggest that transition-metal dichalcogenide interfaces could serve as stable, tunable 1D platform with unique properties for possible use in exploring Majorana fermions, plasma excitations, and spintronics applications.
关键词： spin-orbit coupling,interface states,transition metal dichalcogenides,RKKY interaction,tight-binding model,lateral heterostructures
更新于2025-09-23 15:23:52
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Research on the influence of alignment error on coupling efficiency and beam quality for Gaussian beam to multimode fiber
摘要： The effect of alignment error on the coupling efficiency and beam quality of a Gaussian beam coupled into a large-core multimode fiber is studied in this paper. The equations for evaluating the effect of alignment error on the coupling efficiency are derived separately, and verified with the method of simulation. The calculation and simulation results obtained are highly consistent. In the same way, the effects of alignment error on the beam power distribution are discussed. The results show that the lateral error will change the path of partial light to a large extent, and have a greater influence on the power distribution of the Gaussian beam than the longitudinal error and angular error do.
关键词： Multimode fiber,Coupling efficiency,Beam quality,Alignment error
更新于2025-09-23 15:23:52
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Precision mapping the topological bands of 2D spin-orbit coupling with microwave spin-injection spectroscopy
摘要： To investigate the band structure is one of the key approaches to study the fundamental properties of a novel material. We report here the precision band mapping of a 2-dimensional (2D) spin-orbit (SO) coupling in an optical lattice. By applying the microwave spin-injection spectroscopy, the band structure and spin-polarization distribution are achieved simultaneously. The band topology is also addressed with observing the band gap close and re-open at the Dirac points. Furthermore, the lattice depth and the Raman coupling strength are precisely calibrated with relative errors in the order of 10?3. Our approach could also be applied for exploring the exotic topological phases with even higher dimensional system.
关键词： Topological band,Microwave spin-injection spectroscopy,Spin polarization,Topological phase transition,2D spin-orbit coupling
更新于2025-09-23 15:23:52
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Performance evaluation of mode group power coupling for short reach SDM
摘要： The profound understanding of mode coupling in spatial multiplexed optical systems is required for performance optimization purposes. In this contribution different optical coupler technologies are compared with respect to their bit-error rate (BER) performance as multiplex devices in a (2 × 2) multiple-input multiple-output (MIMO) environment. Therefore, the power coupling coefficients between mode groups for all testbed components are determined at 1327 nm with a method based on impulse response measurements. This method and its refinements are presented in this work. By taking the obtained power coupling coefficients, the MIMO impulse responses are simulated and the corresponding BER performance for different launch parameters is studied. The simulation setup includes single-mode fiber (SMF) to multi-mode fiber (MMF) splices aligned with different radial eccentricities for mode group specific excitation, different multi-mode couplers for mode multiplexing, a 1 km OM4 grade MMF and a multi-mode fusion coupler for demultiplexing. Here, the setup with the customized fusion coupler shows the best BER results in comparison to other coupler technologies. In addition, the optimal choice of the SMF to MMF launch eccentricity highly depends on the implemented coupler technology. Particularly, deviations of 2 μm from the optimal launch setup can lead to a tenfold increase in the BER. It is noteworthy, that the optimal setup does not always include the center launch condition.
关键词： Multi-Mode MIMO,Mode Group Power Coupling,Coupler Technology
更新于2025-09-23 15:23:52
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Giant-Shell CdSe/CdS Nanocrystals: Exciton Coupling to Shell Phonons Investigated by Resonant Raman Spectroscopy
摘要： The interaction between excitons and phonons in semiconductor nanocrystals plays a crucial role in the exciton energy spectrum and dynamics, and thus in their optical properties. We investigate the exciton-phonon coupling in giant-shell CdSe/CdS core-shell nanocrystals via resonant Raman spectroscopy. The Huang-Rhys parameter is evaluated by the intensity ratio of the longitudinal-optical (LO) phonon of CdS with its first multiscattering (2LO) replica. We used four different excitation wavelengths in the range from the onset of the CdS shell absorption to well above the CdS shell band edge to get insight into resonance effects of the CdS LO phonon with high energy excitonic transitions. The isotropic spherical giant-shell nanocrystals show consistently stronger exciton-phonon coupling as compared to the anisotropic rod-shaped dot-in-rod (DiR) architecture, and the 2LO/LO intensity ratio decreases for excitation wavelengths approaching the CdS band edge. The strong exciton-phonon coupling in the spherical giant-shell nanocrystals can be related to the delocalization of the electronic wave functions. Furthermore, we observe the radial breathing modes of the GS nanocrystals and their overtones by ultra-low frequency Raman spectroscopy with nonresonant excitation, using laser energies well below the band gap of the heteronanocrystals, and highlight the differences between higher order optical and acoustic phonon modes.
关键词： Giant-shell nanocrystals,acoustic phonons,Dot-in-rods,Raman spectroscopy,Core-shell heterostructures,exciton-phonon coupling
更新于2025-09-23 15:23:52
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Directing energy into a sub-wavelength non-resonant metasurface across the visible spectrum.
摘要： Group 10 metals (i.e. Ni, Pd, Pt) catalyze a wide range of chemical transformations but the weak interaction of their nanoparticles with light hinders their development for photocatalytic applications. Conversely, coinage metals nanoparticles (particularly Ag and Au) exhibit intense localized surface plasmon resonances in the visible spectrum, but are relatively unreactive, limiting the scope and efficiency of their photochemical processes. Here we demonstrate the design, fabrication and characterization of a new structure containing a single layer of Pd nanoparticles that absorbs up to >98% of visible light. Furthermore, the wavelength of absorption is controlled throughout the visible range of the electromagnetic spectrum by modulating the thickness of a supporting metal oxide film. We show that the absorbed energy is concentrated in the nanoparticle layer, crucial for energy conversion applications including photocatalysis and photothermal processes.
关键词： photocatalysis,plasmonics,metasurfaces,palladium,Hot charge carriers,absorbers,critical coupling
更新于2025-09-23 15:23:52