The gold nano-plates(Au NPLs)have been extensively studied for their high quality factor as mechanical resonators.But it remains still unclear how the thickness and morphology of Au NPLs affect the hot electron diffus...The gold nano-plates(Au NPLs)have been extensively studied for their high quality factor as mechanical resonators.But it remains still unclear how the thickness and morphology of Au NPLs affect the hot electron diffusion.Here we have employed transient absorption microscopy to gain spatiotemporal imaging of the hot electron diffusion in Au NPLs.Au NPLs of varying thickness over 200 nm were synthesized.It was found that the hot electron diffusion of Au NPL excited at the boundary is obviously faster than that excited at the internal surface.And thinner Au NPLs exhibit a faster hot electron diffusion rate compared to thicker Au NPLs.Because the time constant of hot electron cooling(electron-phonon coupling)is independent of the excited position and thickness of Au NPLs,the effect of electron-phonon coupling on hot electron diffusion should be ruled out.So the hot electron diffusion rate is highly dimensionality-dependent.The quasi-one-dimensional diffusion along the boundary of nanoplate has the fastest rate of 50 cm^(2)/s,and the three-dimensional diffusion has the slowest rate of 22 cm^(2)/s.The fundamental investigation on the hot electrons transport property of Au NPLs offers a new insight for designing metal-based optoelectronic devices.展开更多
A novel band to band hot electron programming flash memory device,which features programming with high speed,low voltage,low power consumption,large read current and short access time,is proposed.The new memory cell...A novel band to band hot electron programming flash memory device,which features programming with high speed,low voltage,low power consumption,large read current and short access time,is proposed.The new memory cell is programmed by band to band tunneling induced hot electron (BBHE) injection method at the drain,and erased by Fowler Nordheim tunneling through the source region.The work shows that the programming control gate voltage can be reduced to 8V,and the drain leakage current is only 3μA/μm.Under the proposed operating conditions,the program efficiency and the read current rise up to 4×10 -4 and 60μA/μm,respectively,and the program time can be as short as 16μs展开更多
The effects of atomic number Z on the energy distribution of hot electrons generated by the interaction of 60fs, 130mJ, 800nm, and 7×10^17W/cm^2 laser pulses with metallic targets have been studied experimentally...The effects of atomic number Z on the energy distribution of hot electrons generated by the interaction of 60fs, 130mJ, 800nm, and 7×10^17W/cm^2 laser pulses with metallic targets have been studied experimentally. The results show that the number and the effective temperature of hot electrons increase with the atomic number Z of metallic targets, and the temperature of hot electrons are in the range of 190-230keV, which is consistent with a scaling law of hot electrons temperature.展开更多
Although hot carriers induced degradation of NMOSFETs has been studied for decades, the role of hot electron in this process is still debated. In this paper, the additional substrate hot electrons have been intentiona...Although hot carriers induced degradation of NMOSFETs has been studied for decades, the role of hot electron in this process is still debated. In this paper, the additional substrate hot electrons have been intentionally injected into the oxide layer to analyze tile role of hot electron in hot carrier degradation. The enhanced degradation and the decreased time exponent appear with the injected hot electrons increasing, the degradation increases from 21.80% to 62.00% and the time exponent decreases from 0.59 to 0.27 with Vb decreasing from 0 V to -4 V, at the same time, the recovery also becomes remarkable and which strongly depends on the post stress gate bias Vg. Based on the experimental results, more unrecovered interface traps are created by the additional injected hot electron from the breaking Si-H bond, but the oxide trapped negative charges do not increase after a rapid recovery.展开更多
Understanding the fundamental mechanisms for charge transfer in supported catalysts is of great importance for heterogeneous catalysis. Several experimental and theoretical results suggest that charge flow through met...Understanding the fundamental mechanisms for charge transfer in supported catalysts is of great importance for heterogeneous catalysis. Several experimental and theoretical results suggest that charge flow through metal-support interfaces leads to the catalytic enhancement that is often observed in mixed catalysts. Therefore, it is crucial to directly probe this charge flow in metal-support catalysts during catalytic reactions. In this review, we consider the main aspects of research studying the processes that create and allow interfacial transfer of highly excited（hot） charge carriers in supported catalysts, and discuss the effect of this charge transfer on catalytic activity. We show a close connection between the phenomena of hot electron creation and chemical energy dissipation that accompanies catalytic reactions at both the gas/solid and liquid/solid interfaces. The intensity of hot electron flow is well correlated with the turnover rates of corresponding reactions, which opens up the possibility for developing new operando methodologies for studying chemical processes on catalytic surfaces.展开更多
The transport of hot electrons in inertial confinement fusion(ICF)is integrated issue due to the coupling of hydrodynamic evolution and many physical processes.A hot electron transport code is developed and coupled wi...The transport of hot electrons in inertial confinement fusion(ICF)is integrated issue due to the coupling of hydrodynamic evolution and many physical processes.A hot electron transport code is developed and coupled with the radiation hydrodynamic code MULTI1D in this study.Using the code,the slowing-down process and ablation process of the hot electron beam are simulated.The ablation pressure scaling law of hot electron beam is confirmed in our simulations.The hot electron transport is simulated in the radiation-ablated plasmas relevant to indirect-drive ICF,where the spatial profile of hot electron energy deposition is presented around the shock compressed region.It is shown that the hot electron can prominently increase the total ablation pressure in the early phase of radiation-ablated plasma.So,our study suggests that a potential-driven symmetric mechanism may occur under the irradiation of asymmetric hot electron beam.The possible degradation from the hot electron transport and preheating is also discussed.展开更多
A silver microelectrode with a diameter of 30μm in an aqueous K_(2)SO_(4) electrolyte was irradiated with 55 fs and 213 fs laser pulses.This caused the emission of electrons which transiently charged the electrochemi...A silver microelectrode with a diameter of 30μm in an aqueous K_(2)SO_(4) electrolyte was irradiated with 55 fs and 213 fs laser pulses.This caused the emission of electrons which transiently charged the electrochemical double layer.The two applied pulse durations were significantly shorter than the electron-phonon relaxation time.The laser pulse durations had negligible impact on the emitted charge,which is incompatible with multiphoton emission.On the other hand,the ob-served dependence of emitted charge on laser fluence and electrode potential supports the thermionic emission mechanism.展开更多
We report on the investigation of optimal bias region of a wide-band superconducting hot electron bolometer(HEB)mixer in terms of noise temperature performance for multi-pixel heterodyne receiver application in the 5-...We report on the investigation of optimal bias region of a wide-band superconducting hot electron bolometer(HEB)mixer in terms of noise temperature performance for multi-pixel heterodyne receiver application in the 5-meter Dome A Terahertz Explorer(DATE5)telescope.By evaluating the double sideband(DSB)receiver noise temperature(Trec)across a wide frequency range from 0.2 THz to 1.34 THz and with a large number of bias points,a broad optimal bias region has been observed,illustrating a good bias applicability for multipixel application since the performance of the HEB mixer is uniquely determined by each bias point.The noise temperature of the HEB mixer has been analyzed by calibrating the noise contribution of all RF components,whose transmissions have been measured by a time-domain spectroscopy.The corrected noise temperature distribution shows a frequency independence relation.The dependence of the optimal bias region on the bath temperature of the HEB mixer has also been investigated,the bath temperature has limited effect on the lowest receiver noise temperature until 7 K,however the optimal bias region deteriorates obviously with increasing bath temperature.展开更多
In this paper, （2＋1）-dimensional electron acoustic waves （EAW） in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique, respectively. The disper...In this paper, （2＋1）-dimensional electron acoustic waves （EAW） in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique, respectively. The dispersion relation and a modified Kadomtsev-Petviashvili （KP） equation have been obtained for the EAW in the plasma considering a cold electron fluid and a vortex-like hot electrons. It is found from some numerical results that the parameter β（the ratio of the free hot electron temperature to the hot trapped electron temperature） effects on the amplitude and the Width of the electron acoustic solitary waves （EASW）. It can be indicated that the free hot electron temperature and the hot trapped electron temperature have very important effect on the characters of the propagation for the EASW.展开更多
Terahertz （THz） direct detectors based on superconducting niobium nitride （NbN） hot electron bolometers （HEBs） with microwave （MW） biasing are studied. The MW is used to bias the HEB to the optimum point and t...Terahertz （THz） direct detectors based on superconducting niobium nitride （NbN） hot electron bolometers （HEBs） with microwave （MW） biasing are studied. The MW is used to bias the HEB to the optimum point and to readout the impedance changes caused by the incident THz signals. Compared with the thermal biasing method, this method would be more promising in large scale array with simple readout. The used NbN HEB has an excellent performance as heterodyne detector with the double sideband noise temperature （T N） of 403K working at 4.2K and 0.65THz. As a result, the noise equivalent power of 1.5pW/Hz 1/2 and the response time of 64ps are obtained for the direct detectors based on the NbN HEBs and working at 4.2K and 0.65THz.展开更多
Making use of disk targets composed of several peculiar materials (foamAn, foam C8H8) and hohlraum with a special structure, experiments have been doneat "Xing Guang - II" laser facility, which study the cha...Making use of disk targets composed of several peculiar materials (foamAn, foam C8H8) and hohlraum with a special structure, experiments have been doneat "Xing Guang - II" laser facility, which study the characteristics of hot electronsand the related nonlinear processes such as Stimulated airman Scattering (SRS), TwoPlasma Decay (TPD), Stimulated Brillouin Scattering (SBS), etc.展开更多
Plasmon-induced hot energy in metal nanostructures holds great promise for photocatalytic organic conversions.However,maintaining the high-energy state of hot electrons within these structures remains challenging,even...Plasmon-induced hot energy in metal nanostructures holds great promise for photocatalytic organic conversions.However,maintaining the high-energy state of hot electrons within these structures remains challenging,even in hybrid metal-semiconductor heterojunctions.The rapid relaxation of hot electrons(<1 ps)due to a thick-shell and loosely bound semiconductor layer limits their extraction efficiency and utilization effectiveness during photocatalysis.Herein,we fabricated a novel metalsemiconductor heterojunction(P2-Au)with ultrathin-shell semiconductor layer by combing ultra-small metal chalcogenide semiconductor clusters(P2)with gold nanorods(Au NRs),which exhibits high-efficiency extraction of hot electrons and photocatalytic application.The robust binding of P2 cluster,with its smaller volume and larger energy level splitting compared to large-sized quantum dots,not only significantly increases the yield of hot electrons but also enables their rapid extraction and sustains long-lived(>2 ns)high-energy states.As a proof of concept,the composite photocatalyst achieves near-infrared-lightdriven C(sp^(3))-S cross-coupling reactions for the first time.This protocol effectively produces over 50 alkylthioethers from a wide scope range of non-active alkyl bromides and chlorides,aryl and alkyl thiols.This work provides a new strategy for highefficiency extraction of hot electrons within plasmonic metal nanostructures and paves the way for hot electron-driven photocatalytic organic transformations.展开更多
We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using K...We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using Ka time-resolved imaging,it is found that in the case of massive targets,the hot-electron generation follows the laser pulse intensity with a short delay needed for favorable plasma formation.Conversely,a significant delay in the x-ray emission compared with the laser pulse intensity profile is observed in the case of thin targets.Theoretical analysis and numerical simulations suggest that this is related to radiation preheating of the foil and the increase in hot-electron lifetime in a hot expanding plasma.展开更多
Efficient CO_(2) photoreduction towards C_(2+)solar fuels has emerged as one of the most promising strategies for alleviating the current energy and environment problems.However,the C-C coupling barriers and complex m...Efficient CO_(2) photoreduction towards C_(2+)solar fuels has emerged as one of the most promising strategies for alleviating the current energy and environment problems.However,the C-C coupling barriers and complex multi-electron transfer steps still limit the activity and selectivity of CO_(2)-to-C_(2) photoreduction.Herein,Au nanoparticles(NPs)modified CeO_(2) with oxygen vacancies(Au/CeO_(2)-VO)were reported for enhancing the CO_(2)-to-C_(2)H_(6) photoreduction performance.Au/CeO_(2)-VO achieved the high C_(2)H_(6) activity of 51.7μmol·g^(-1)·h^(-1),accompanied with C_(2)H_(6) selectivity up to 80% in the absence of sacrificial agent.Experimental results combined with theoretical simulation indicated that VO strengthened CO_(2) adsorption and activated*CO production,and plasmon-induced hot electrons from Au NPs to CeO_(2)-VO facilitated the*CO-*CO dimerization.The synergistic modulation of VO and hot electrons further decreased the energy barriers of C-C coupling and subsequent hydrogenation,resulting in the superior photoreduction performance.This work opens an avenue of developing plasmonic photocatalysts for multi-carbon products from CO_(2) photoreduction.展开更多
Narrowband photodetection is an important measurement technique for material analysis and sensing,for example,nondispersive infrared sensing technique.Both photoactive material engineering and nanophotonic filtering s...Narrowband photodetection is an important measurement technique for material analysis and sensing,for example,nondispersive infrared sensing technique.Both photoactive material engineering and nanophotonic filtering schemes have been explored to realize wavelength-selective photodetection,while most devices have a responsive bandwidth larger than 2%of the operating wavelength,limiting sensing performance.Near-infrared photodetection with a bandwidth of less than 0.2%of the operating wavelength was demonstrated experimentally in Au/Si Schottky nanojunctions.A minimum linewidth of photoelectric response down to 2.6 nm was obtained at a wavelength of 1550 nm by carefully tailing the absorptive and radiative loss in the nanostructures.Multiple functions were achieved on chip with the corrugated Au film,including narrowband resonance,light harvesting for sensing and photodetection,and electrodes for hot electron emission.Benefiting from such a unity integration with in situ photoelectric conversion of the optical sensing signal and the ultranarrowband resonance,self-contained on-chip biosensing via simple intensity interrogation was demonstrated with a limit of detection down to 0.0047%in concentration for glucose solution and 150 ng∕m L for rabbit IgG.Promising potential of this technique is expected for the applications in on-site sensing,spectroscopy,spectral imaging,etc.展开更多
Solar-driven water splitting has emerged as a promising route for sustainable hydrogen generation,however,developing broad-spectrum responsive photocatalysts remains a challenge for achieving efficient solar-to-hydrog...Solar-driven water splitting has emerged as a promising route for sustainable hydrogen generation,however,developing broad-spectrum responsive photocatalysts remains a challenge for achieving efficient solar-to-hydrogen conversion.Here,we demonstrate a g-C_(3)N_(4)-based(UCN)catalyst with dispersed Ag single atoms(Ag SAs)and Ag nanoparticles(Ag NPs)for synergistically broad-spectrum photocatalytic hydrogen evolution.Experimental and theoretical results reveal that both Ag SAs and Ag NPs serve as active sites,with the Schottky junction between Ag NPs and g-C_(3)N_(4)effectively promoting charge separation,while Ag NPs induce localized surface plasmon resonance,extending the light response range from visible to near-infrared regions.The optimized catalyst Ag-UCN-3 exhibits a hydrogen evolution rate as high as 22.11 mmol/g/h and an apparent quantum efficiency(AQE)of 10.16%under 420 nm light illumination.Notably,it still had a high hydrogen evolution rate of 633.57μmol/g/h under 700 nm irradiation.This work unveils dual active sites engineering strategy that couples Ag SAs and Ag NPs with plasma and hot electrons,offering a new strategy for designing high-performance solar-driven energy systems.展开更多
Design and synthesis of efficient photocatalysts for hydrogen production via water splitting are of great importance from both theoretical and practical viewpoints. Many metal-based semiconductors have been explored f...Design and synthesis of efficient photocatalysts for hydrogen production via water splitting are of great importance from both theoretical and practical viewpoints. Many metal-based semiconductors have been explored for this purpose in recent decades. Here, for the first time, an entirely carbon-based material, bulk three-dimensionally cross-linked graphene （3DG）, has been developed as a photocatalyst for hydrogen production. It exhibits a remarkable hydrogen production rate of 270 μmol-h-l.g-t under full-spectrum light via a hot/free electron emission mechanism. Furthermore, when combined with the widely used semiconductor TiO2 to form a TiO2/3DG composite, it appears to become a more efficient hydrogen production photocatalyst. The composite achieves a production rate of 1,205 bimol-h μg-t under ultraviolet-visible （UV-vis） light and a 7.2% apparent quantum efficiency at 350 nm due to the strong synergetic effects between TiO2 and 3DG.展开更多
We present a theoretical and experimental study of a plasmonic nanoelectrode architecture that is able to inject bunches of hot electrons into an aqueous environment.In this approach,electrons are accelerated in water...We present a theoretical and experimental study of a plasmonic nanoelectrode architecture that is able to inject bunches of hot electrons into an aqueous environment.In this approach,electrons are accelerated in water by ponderomotive forces up to energies capable of exciting or ionizing water molecules.This ability is enabled by the nanoelectrode structure(extruding out of a metal baseplate),which allows for the production of an intense plasmonic hot spot at the apex of the structure while maintaining the electrical connection to a virtually unlimited charge reservoir.The electron injection is experimentally monitored by recording the current transmitted through the water medium,whereas the electron acceleration is confirmed by observation of the bubble generation for a laser power exceeding a proper threshold.An understanding of the complex physics involved is obtained via a numerical approach that explicitly models the electromagnetic hot spot generation,electron-by-electron injection via multiphoton absorption,acceleration by ponderomotive forces and electron-water interaction through random elastic and inelastic scattering.The model predicts a critical electron density for bubble nucleation that nicely matches the experimental findings and reveals that the efficiency of energy transfer from the plasmonic hot spot to the free electron cloud is much more efficient(17 times higher)in water than in a vacuum.Because of their high kinetic energy and large reduction potential,these proposed wet hot electrons may provide new opportunities in photocatalysis,electrochemical processes and hot-electron driven chemistry.展开更多
Gold(Au)plasmonic nanoparticles were grown evenly on monolayer graphitic carbon nitride(g‐C3N4)nanosheets via a facile oil‐bath method.The photocatalytic activity of the Au/monolayer g‐C3N4 composites under visible...Gold(Au)plasmonic nanoparticles were grown evenly on monolayer graphitic carbon nitride(g‐C3N4)nanosheets via a facile oil‐bath method.The photocatalytic activity of the Au/monolayer g‐C3N4 composites under visible light was evaluated by photocatalytic hydrogen evolution and environmental treatment.All of the Au/monolayer g‐C3N4 composites showed better photocatalytic performance than that of monolayer g‐C3N4 and the 1%Au/monolayer g‐C3N4 composite displayed the highest photocatalytic hydrogen evolution rate of the samples.The remarkable photocatalytic activity was attributed largely to the successful introduction of Au plasmonic nanoparticles,which led to the surface plasmon resonance(SPR)effect.The SPR effect enhanced the efficiency of light harvesting and induced an efficient hot electron transfer process.The hot electrons were injected from the Au plasmonic nanoparticles into the conduction band of monolayer g‐C3N4.Thus,the Au/monolayer g‐C3N4 composites possessed higher migration and separation efficiencies and lower recombination probability of photogenerated electron‐hole pairs than those of monolayer g‐C3N4.A photocatalytic mechanism for the composites was also proposed.展开更多
基金supported by the National Natural Science Foundation of China(No.22273006).
文摘The gold nano-plates(Au NPLs)have been extensively studied for their high quality factor as mechanical resonators.But it remains still unclear how the thickness and morphology of Au NPLs affect the hot electron diffusion.Here we have employed transient absorption microscopy to gain spatiotemporal imaging of the hot electron diffusion in Au NPLs.Au NPLs of varying thickness over 200 nm were synthesized.It was found that the hot electron diffusion of Au NPL excited at the boundary is obviously faster than that excited at the internal surface.And thinner Au NPLs exhibit a faster hot electron diffusion rate compared to thicker Au NPLs.Because the time constant of hot electron cooling(electron-phonon coupling)is independent of the excited position and thickness of Au NPLs,the effect of electron-phonon coupling on hot electron diffusion should be ruled out.So the hot electron diffusion rate is highly dimensionality-dependent.The quasi-one-dimensional diffusion along the boundary of nanoplate has the fastest rate of 50 cm^(2)/s,and the three-dimensional diffusion has the slowest rate of 22 cm^(2)/s.The fundamental investigation on the hot electrons transport property of Au NPLs offers a new insight for designing metal-based optoelectronic devices.
文摘A novel band to band hot electron programming flash memory device,which features programming with high speed,low voltage,low power consumption,large read current and short access time,is proposed.The new memory cell is programmed by band to band tunneling induced hot electron (BBHE) injection method at the drain,and erased by Fowler Nordheim tunneling through the source region.The work shows that the programming control gate voltage can be reduced to 8V,and the drain leakage current is only 3μA/μm.Under the proposed operating conditions,the program efficiency and the read current rise up to 4×10 -4 and 60μA/μm,respectively,and the program time can be as short as 16μs
基金Project supported by the National Natural Science Foundation of China （Grant No 10275056） and the Science and Technology 0ffice of Sichuan, China （Grant 04JY029-097）.
文摘The effects of atomic number Z on the energy distribution of hot electrons generated by the interaction of 60fs, 130mJ, 800nm, and 7×10^17W/cm^2 laser pulses with metallic targets have been studied experimentally. The results show that the number and the effective temperature of hot electrons increase with the atomic number Z of metallic targets, and the temperature of hot electrons are in the range of 190-230keV, which is consistent with a scaling law of hot electrons temperature.
基金supported by the National Natural Science Foundation of China(Grant No.61376109)the Opening Project of National Key Laboratory of Science and Technology on Reliability Physics and Application Technology of Electrical Component,China(Grant No.ZHD201202)
文摘Although hot carriers induced degradation of NMOSFETs has been studied for decades, the role of hot electron in this process is still debated. In this paper, the additional substrate hot electrons have been intentionally injected into the oxide layer to analyze tile role of hot electron in hot carrier degradation. The enhanced degradation and the decreased time exponent appear with the injected hot electrons increasing, the degradation increases from 21.80% to 62.00% and the time exponent decreases from 0.59 to 0.27 with Vb decreasing from 0 V to -4 V, at the same time, the recovery also becomes remarkable and which strongly depends on the post stress gate bias Vg. Based on the experimental results, more unrecovered interface traps are created by the additional injected hot electron from the breaking Si-H bond, but the oxide trapped negative charges do not increase after a rapid recovery.
基金supported by the Institute for Basic Science (IBS, Republic of Korea) (No. IBS-R004-A2-2017-a00)
文摘Understanding the fundamental mechanisms for charge transfer in supported catalysts is of great importance for heterogeneous catalysis. Several experimental and theoretical results suggest that charge flow through metal-support interfaces leads to the catalytic enhancement that is often observed in mixed catalysts. Therefore, it is crucial to directly probe this charge flow in metal-support catalysts during catalytic reactions. In this review, we consider the main aspects of research studying the processes that create and allow interfacial transfer of highly excited（hot） charge carriers in supported catalysts, and discuss the effect of this charge transfer on catalytic activity. We show a close connection between the phenomena of hot electron creation and chemical energy dissipation that accompanies catalytic reactions at both the gas/solid and liquid/solid interfaces. The intensity of hot electron flow is well correlated with the turnover rates of corresponding reactions, which opens up the possibility for developing new operando methodologies for studying chemical processes on catalytic surfaces.
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA25050600)the DCI joint team。
文摘The transport of hot electrons in inertial confinement fusion(ICF)is integrated issue due to the coupling of hydrodynamic evolution and many physical processes.A hot electron transport code is developed and coupled with the radiation hydrodynamic code MULTI1D in this study.Using the code,the slowing-down process and ablation process of the hot electron beam are simulated.The ablation pressure scaling law of hot electron beam is confirmed in our simulations.The hot electron transport is simulated in the radiation-ablated plasmas relevant to indirect-drive ICF,where the spatial profile of hot electron energy deposition is presented around the shock compressed region.It is shown that the hot electron can prominently increase the total ablation pressure in the early phase of radiation-ablated plasma.So,our study suggests that a potential-driven symmetric mechanism may occur under the irradiation of asymmetric hot electron beam.The possible degradation from the hot electron transport and preheating is also discussed.
文摘A silver microelectrode with a diameter of 30μm in an aqueous K_(2)SO_(4) electrolyte was irradiated with 55 fs and 213 fs laser pulses.This caused the emission of electrons which transiently charged the electrochemical double layer.The two applied pulse durations were significantly shorter than the electron-phonon relaxation time.The laser pulse durations had negligible impact on the emitted charge,which is incompatible with multiphoton emission.On the other hand,the ob-served dependence of emitted charge on laser fluence and electrode potential supports the thermionic emission mechanism.
基金Project supported by the Chinese Academy of Sciences(Grant Nos.GJJSTD20180003 and QYZDJ-SSW-SLH043)the National Key Basic Research and Development Program of China(Grant Nos.2017YFA0304003 and 2018YFA0404701)+1 种基金the National Natural Science Foundation of China(Grant Nos.11603081,11673073,U1831202,and 11873099)PICS projects between the CAS and the CNRS.
文摘We report on the investigation of optimal bias region of a wide-band superconducting hot electron bolometer(HEB)mixer in terms of noise temperature performance for multi-pixel heterodyne receiver application in the 5-meter Dome A Terahertz Explorer(DATE5)telescope.By evaluating the double sideband(DSB)receiver noise temperature(Trec)across a wide frequency range from 0.2 THz to 1.34 THz and with a large number of bias points,a broad optimal bias region has been observed,illustrating a good bias applicability for multipixel application since the performance of the HEB mixer is uniquely determined by each bias point.The noise temperature of the HEB mixer has been analyzed by calibrating the noise contribution of all RF components,whose transmissions have been measured by a time-domain spectroscopy.The corrected noise temperature distribution shows a frequency independence relation.The dependence of the optimal bias region on the bath temperature of the HEB mixer has also been investigated,the bath temperature has limited effect on the lowest receiver noise temperature until 7 K,however the optimal bias region deteriorates obviously with increasing bath temperature.
基金The project supported by National Natural Science Foundation of China under Grant No. 10575082
文摘In this paper, （2＋1）-dimensional electron acoustic waves （EAW） in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique, respectively. The dispersion relation and a modified Kadomtsev-Petviashvili （KP） equation have been obtained for the EAW in the plasma considering a cold electron fluid and a vortex-like hot electrons. It is found from some numerical results that the parameter β（the ratio of the free hot electron temperature to the hot trapped electron temperature） effects on the amplitude and the Width of the electron acoustic solitary waves （EASW）. It can be indicated that the free hot electron temperature and the hot trapped electron temperature have very important effect on the characters of the propagation for the EASW.
基金Supported by the National Basic Research Program of China under Grant No 2014CB339800the National Natural Science Foundation of China under Grant Nos 61521001,11173015 and 11227904+1 种基金the Fundamental Research Funds for the Central Universitiesthe Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves of Jiangsu Province
文摘Terahertz （THz） direct detectors based on superconducting niobium nitride （NbN） hot electron bolometers （HEBs） with microwave （MW） biasing are studied. The MW is used to bias the HEB to the optimum point and to readout the impedance changes caused by the incident THz signals. Compared with the thermal biasing method, this method would be more promising in large scale array with simple readout. The used NbN HEB has an excellent performance as heterodyne detector with the double sideband noise temperature （T N） of 403K working at 4.2K and 0.65THz. As a result, the noise equivalent power of 1.5pW/Hz 1/2 and the response time of 64ps are obtained for the direct detectors based on the NbN HEBs and working at 4.2K and 0.65THz.
文摘Making use of disk targets composed of several peculiar materials (foamAn, foam C8H8) and hohlraum with a special structure, experiments have been doneat "Xing Guang - II" laser facility, which study the characteristics of hot electronsand the related nonlinear processes such as Stimulated airman Scattering (SRS), TwoPlasma Decay (TPD), Stimulated Brillouin Scattering (SBS), etc.
基金supported by the National Natural Science Foundation of China(U22A20432,92261205,22071165,22201103)the 111 Project(D20015)+2 种基金the Guangzhou Municipal Science and Technology Bureau(2024A04J3490)supported by the State Key Laboratory of Bioactive Molecules and Druggability Assessment(202402025)the Fundamental Research Funds for the Central Universities。
文摘Plasmon-induced hot energy in metal nanostructures holds great promise for photocatalytic organic conversions.However,maintaining the high-energy state of hot electrons within these structures remains challenging,even in hybrid metal-semiconductor heterojunctions.The rapid relaxation of hot electrons(<1 ps)due to a thick-shell and loosely bound semiconductor layer limits their extraction efficiency and utilization effectiveness during photocatalysis.Herein,we fabricated a novel metalsemiconductor heterojunction(P2-Au)with ultrathin-shell semiconductor layer by combing ultra-small metal chalcogenide semiconductor clusters(P2)with gold nanorods(Au NRs),which exhibits high-efficiency extraction of hot electrons and photocatalytic application.The robust binding of P2 cluster,with its smaller volume and larger energy level splitting compared to large-sized quantum dots,not only significantly increases the yield of hot electrons but also enables their rapid extraction and sustains long-lived(>2 ns)high-energy states.As a proof of concept,the composite photocatalyst achieves near-infrared-lightdriven C(sp^(3))-S cross-coupling reactions for the first time.This protocol effectively produces over 50 alkylthioethers from a wide scope range of non-active alkyl bromides and chlorides,aryl and alkyl thiols.This work provides a new strategy for highefficiency extraction of hot electrons within plasmonic metal nanostructures and paves the way for hot electron-driven photocatalytic organic transformations.
基金funding via EUROfusion Enabling research Project No.AWP21-ENR-01-CEA-02“Advancing Shock Ignition for Direct-Drive Inertial Fusion,”the framework of the EUROfusion Consortium,funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No.101052200-EUROfusion)+2 种基金the Czech Ministry of Education,Youth and Sports (CMEYS) for funding the operation of the PALS facility (Grant No.LM2023068)the EuroHPC Joint Undertaking for awarding access to Karolina at IT4Innovations (VSB-TU),Czechia under Project No.EHPC-REG-2023R02-006(DD-23-157)the Ministry of Education,Youth and Sports of the Czech Republic through e-INFRA CZ (Grant No.ID:90140)
文摘We investigate the spatial and temporal correlations of hot-electron generation in high-intensity laser interaction with massive and thin copper targets under conditions relevant to inertial confinement fusion.Using Ka time-resolved imaging,it is found that in the case of massive targets,the hot-electron generation follows the laser pulse intensity with a short delay needed for favorable plasma formation.Conversely,a significant delay in the x-ray emission compared with the laser pulse intensity profile is observed in the case of thin targets.Theoretical analysis and numerical simulations suggest that this is related to radiation preheating of the foil and the increase in hot-electron lifetime in a hot expanding plasma.
基金supported by the National Natural Science Foundation of China(Nos.22302002 and 22375006)the University Science Research Project of Anhui Province(Nos.2022AH050182 and 2022AH020020).
文摘Efficient CO_(2) photoreduction towards C_(2+)solar fuels has emerged as one of the most promising strategies for alleviating the current energy and environment problems.However,the C-C coupling barriers and complex multi-electron transfer steps still limit the activity and selectivity of CO_(2)-to-C_(2) photoreduction.Herein,Au nanoparticles(NPs)modified CeO_(2) with oxygen vacancies(Au/CeO_(2)-VO)were reported for enhancing the CO_(2)-to-C_(2)H_(6) photoreduction performance.Au/CeO_(2)-VO achieved the high C_(2)H_(6) activity of 51.7μmol·g^(-1)·h^(-1),accompanied with C_(2)H_(6) selectivity up to 80% in the absence of sacrificial agent.Experimental results combined with theoretical simulation indicated that VO strengthened CO_(2) adsorption and activated*CO production,and plasmon-induced hot electrons from Au NPs to CeO_(2)-VO facilitated the*CO-*CO dimerization.The synergistic modulation of VO and hot electrons further decreased the energy barriers of C-C coupling and subsequent hydrogenation,resulting in the superior photoreduction performance.This work opens an avenue of developing plasmonic photocatalysts for multi-carbon products from CO_(2) photoreduction.
基金financial support from the National Natural Science Foundation of China(Grant Nos.62220106001 and 92050108)the Key Research and Development Program of Guangdong Province(Grant No.2023B0101200009)+3 种基金the Guangdong Science and Technology Program International Cooperation Program(Grant No.2021A0505030038)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022B1515020069)the Pearl River Talent Plan Program of Guangdong(Grant No.2019QN01X120)the technical support from Nano Fabrication Facility and Nano-X of SINANO,CAS
文摘Narrowband photodetection is an important measurement technique for material analysis and sensing,for example,nondispersive infrared sensing technique.Both photoactive material engineering and nanophotonic filtering schemes have been explored to realize wavelength-selective photodetection,while most devices have a responsive bandwidth larger than 2%of the operating wavelength,limiting sensing performance.Near-infrared photodetection with a bandwidth of less than 0.2%of the operating wavelength was demonstrated experimentally in Au/Si Schottky nanojunctions.A minimum linewidth of photoelectric response down to 2.6 nm was obtained at a wavelength of 1550 nm by carefully tailing the absorptive and radiative loss in the nanostructures.Multiple functions were achieved on chip with the corrugated Au film,including narrowband resonance,light harvesting for sensing and photodetection,and electrodes for hot electron emission.Benefiting from such a unity integration with in situ photoelectric conversion of the optical sensing signal and the ultranarrowband resonance,self-contained on-chip biosensing via simple intensity interrogation was demonstrated with a limit of detection down to 0.0047%in concentration for glucose solution and 150 ng∕m L for rabbit IgG.Promising potential of this technique is expected for the applications in on-site sensing,spectroscopy,spectral imaging,etc.
文摘Solar-driven water splitting has emerged as a promising route for sustainable hydrogen generation,however,developing broad-spectrum responsive photocatalysts remains a challenge for achieving efficient solar-to-hydrogen conversion.Here,we demonstrate a g-C_(3)N_(4)-based(UCN)catalyst with dispersed Ag single atoms(Ag SAs)and Ag nanoparticles(Ag NPs)for synergistically broad-spectrum photocatalytic hydrogen evolution.Experimental and theoretical results reveal that both Ag SAs and Ag NPs serve as active sites,with the Schottky junction between Ag NPs and g-C_(3)N_(4)effectively promoting charge separation,while Ag NPs induce localized surface plasmon resonance,extending the light response range from visible to near-infrared regions.The optimized catalyst Ag-UCN-3 exhibits a hydrogen evolution rate as high as 22.11 mmol/g/h and an apparent quantum efficiency(AQE)of 10.16%under 420 nm light illumination.Notably,it still had a high hydrogen evolution rate of 633.57μmol/g/h under 700 nm irradiation.This work unveils dual active sites engineering strategy that couples Ag SAs and Ag NPs with plasma and hot electrons,offering a new strategy for designing high-performance solar-driven energy systems.
文摘Design and synthesis of efficient photocatalysts for hydrogen production via water splitting are of great importance from both theoretical and practical viewpoints. Many metal-based semiconductors have been explored for this purpose in recent decades. Here, for the first time, an entirely carbon-based material, bulk three-dimensionally cross-linked graphene （3DG）, has been developed as a photocatalyst for hydrogen production. It exhibits a remarkable hydrogen production rate of 270 μmol-h-l.g-t under full-spectrum light via a hot/free electron emission mechanism. Furthermore, when combined with the widely used semiconductor TiO2 to form a TiO2/3DG composite, it appears to become a more efficient hydrogen production photocatalyst. The composite achieves a production rate of 1,205 bimol-h μg-t under ultraviolet-visible （UV-vis） light and a 7.2% apparent quantum efficiency at 350 nm due to the strong synergetic effects between TiO2 and 3DG.
基金the European Research Council under the European Union’s Seventh Framework Program(FP/2007-2013)/ERC Grant Agreement No.[616213]CoG:Neuro-Plasmonics and under the Horizon 2020 Program,FET-Open:PROSEQO,Grant Agreement No.[687089].
文摘We present a theoretical and experimental study of a plasmonic nanoelectrode architecture that is able to inject bunches of hot electrons into an aqueous environment.In this approach,electrons are accelerated in water by ponderomotive forces up to energies capable of exciting or ionizing water molecules.This ability is enabled by the nanoelectrode structure(extruding out of a metal baseplate),which allows for the production of an intense plasmonic hot spot at the apex of the structure while maintaining the electrical connection to a virtually unlimited charge reservoir.The electron injection is experimentally monitored by recording the current transmitted through the water medium,whereas the electron acceleration is confirmed by observation of the bubble generation for a laser power exceeding a proper threshold.An understanding of the complex physics involved is obtained via a numerical approach that explicitly models the electromagnetic hot spot generation,electron-by-electron injection via multiphoton absorption,acceleration by ponderomotive forces and electron-water interaction through random elastic and inelastic scattering.The model predicts a critical electron density for bubble nucleation that nicely matches the experimental findings and reveals that the efficiency of energy transfer from the plasmonic hot spot to the free electron cloud is much more efficient(17 times higher)in water than in a vacuum.Because of their high kinetic energy and large reduction potential,these proposed wet hot electrons may provide new opportunities in photocatalysis,electrochemical processes and hot-electron driven chemistry.
文摘Gold(Au)plasmonic nanoparticles were grown evenly on monolayer graphitic carbon nitride(g‐C3N4)nanosheets via a facile oil‐bath method.The photocatalytic activity of the Au/monolayer g‐C3N4 composites under visible light was evaluated by photocatalytic hydrogen evolution and environmental treatment.All of the Au/monolayer g‐C3N4 composites showed better photocatalytic performance than that of monolayer g‐C3N4 and the 1%Au/monolayer g‐C3N4 composite displayed the highest photocatalytic hydrogen evolution rate of the samples.The remarkable photocatalytic activity was attributed largely to the successful introduction of Au plasmonic nanoparticles,which led to the surface plasmon resonance(SPR)effect.The SPR effect enhanced the efficiency of light harvesting and induced an efficient hot electron transfer process.The hot electrons were injected from the Au plasmonic nanoparticles into the conduction band of monolayer g‐C3N4.Thus,the Au/monolayer g‐C3N4 composites possessed higher migration and separation efficiencies and lower recombination probability of photogenerated electron‐hole pairs than those of monolayer g‐C3N4.A photocatalytic mechanism for the composites was also proposed.
