Heterogeneous catalysis at the metal surface generally involves the transport of molecules through the interfacial water layer to access the surface,which is a rate-determining step at the nanoscale.In this study,taki...Heterogeneous catalysis at the metal surface generally involves the transport of molecules through the interfacial water layer to access the surface,which is a rate-determining step at the nanoscale.In this study,taking the oxygen reduction reaction on a metal electrode in aqueous solution as an example,using accurate molecular dynamic simulations,we propose a novel long-range regulation strategy in which midinfrared stimulation(MIRS)with a frequency of approximately 1,000 cm^(-1)is applied to nonthermally induce the structural transition of interfacial water from an ordered to disordered state,facilitating the access of oxygen molecules to metal surfaces at room temperature and increasing the oxygen reduction activity 50-fold.Impressively,the theoretical prediction is confirmed by the experimental observation of a significant discharge voltage increase in zinc-air batteries under MIRS.This MIRS approach can be seamlessly integrated into existing strategies,offering a new approach for accelerating heterogeneous reactions and gas sensing within the interfacial water system.展开更多
Free-space optical communication is a very promising alternative to fiber communication systems,in terms of ease of deployment and costs.Midinfrared light has several features of utter relevance for free-space applica...Free-space optical communication is a very promising alternative to fiber communication systems,in terms of ease of deployment and costs.Midinfrared light has several features of utter relevance for free-space applications:low absorption when propagating in the atmosphere even under adverse conditions,robustness of the wavefront during long-distance propagation,and absence of regulations and restrictions for this range of wavelengths.A proof-of-concept of high-speed transmission taking advantage of intersubband devices has recently been demonstrated,but this effort was limited by the short-distance optical path(up to 1 m).In this work,we study the possibility of building a long-range link using unipolar quantum optoelectronics.Two different detectors are used:an uncooled quantum cascade detector and a nitrogen-cooled quantum well-infrared photodetector.We evaluate the maximum data rate of our link in a back-to-back configuration before adding a Herriott cell to increase the length of the light path up to 31 m.By using pulse shaping,pre-and post-processing,we reach a record bitrate of 30 Gbit s−1 for both two-level(OOK)and four-level(PAM-4)modulation schemes for a 31-m propagation link and a bit error rate compatible with error-correction codes.展开更多
We demonstrated stable midinfrared(MIR) optical frequency comb at the 3.0 μm region with difference frequency generation pumped by a high power, Er-doped, ultrashort pulse fiber laser system. A soliton mode-locked161...We demonstrated stable midinfrared(MIR) optical frequency comb at the 3.0 μm region with difference frequency generation pumped by a high power, Er-doped, ultrashort pulse fiber laser system. A soliton mode-locked161 MHz high repetition rate fiber laser using a single wall carbon nanotube was fabricated. The output pulse was amplified in an Er-doped single mode fiber amplifier, and a 1.1–2.2 μm wideband supercontinuum(SC) with an average power of 205 m W was generated in highly nonlinear fiber. The spectrogram of the generated SC was examined both experimentally and numerically. The generated SC was focused into a nonlinear crystal, and stable generation of MIR comb around the 3 μm wavelength region was realized.展开更多
Photoinduced carrier dynamical processes dominate the optical excitation properties of photocatalysts and further determine the photocatalytic performance.In addition,as the electrons generally possess a faster transf...Photoinduced carrier dynamical processes dominate the optical excitation properties of photocatalysts and further determine the photocatalytic performance.In addition,as the electrons generally possess a faster transfer rate than holes,hole transfer and accumulation are critical,and they play the key efficiency-limiting step during the photocatalytic process.Therefore,a comprehensive understanding of the dynamics of photogenerated holes and their determining factors in the photocatalytic system is highly essential to rationalize the full catalytic mechanism and develop highly efficient photocatalysts,which have not yet been revealed.In this work,the photoinduced charge carrier dynamics in InP/ZnS quantum dots(QDs)capped with longchain L-typed ligands(oleylamine)and inorganic ligands(sulfide ion(S^(2-)))were explored.Time-resolved photoluminescence and femtosecond transient-absorption spectroscopy unambiguously confirmed the ultrafast hole transfer from the InP core to S^(2-)ligands.Moreover,by probing the bleach of vibrational stretching of the ligands with transient midinfrared absorption spectroscopy,the hole transfer time was determined to be 4.2 ps.The injected holes are long-lived at the S^(2-) ligands(>4.5 ns),and they can remove electrostatically attached surfactants to compensate for the spatial charge redistribution.Finally,compared with other inorganic ligands such as Cl^(-) and PO_(4)^(3-),S^(2-) balances the ionic radii and net charge to ensure the optimal condition for charge transfer.Such observation rationalizes the excellent photocatalytic H_(2) evolution(213.6μmol mg^(-1) within 10 h)in InP/ZnS QDs capped with S^(2-) compared with those capped with other ligands and elucidates the role of surface ligands in the photocatalytic activity of colloidal QDs.展开更多
GSMBE grown 1 84 micron wavelength InGaAs/InGaAsP/InP strained quantum well lasers are reported. Lasers with 800 micron long cavity and 40 micron wide planar electrical stripe have been operated under the pulsed r...GSMBE grown 1 84 micron wavelength InGaAs/InGaAsP/InP strained quantum well lasers are reported. Lasers with 800 micron long cavity and 40 micron wide planar electrical stripe have been operated under the pulsed regime at room temperature. At 20℃, the threshold current density is 3 8kA/cm 2 and the external different quantum efficiency is 9 3%.展开更多
Acentral theme of chemical imaging is the visualization of chemistry in situ in functional materials and in vivo in a living system.To achieve this,technologies with exceptional detection sensitivity and spatial resol...Acentral theme of chemical imaging is the visualization of chemistry in situ in functional materials and in vivo in a living system.To achieve this,technologies with exceptional detection sensitivity and spatial resolution are essential for resolving specific chemicals at the nanoscale.As we celebrate the 10th anniversary of the Nobel Prize in Chemistry awarded for super-resolved fluorescence microscopy,the field’s remarkable advancements become clear.Over the past 10 years,novel microscopies that break light diffraction limits continue to be invented.These include,for example,midinfrared photothermal microscopy that breaks the diffraction limit in IR imaging,and expansion microscopy that allows super-resolution fluorescence imaging on a conventional microscope.Meanwhile,researchers have much increased the speed of structural illumination microscopy(SIM)and single molecule localization microscopy(SMLM),and pushed the resolution limit of stimulated emission depletion(STED)microscopy to angstrom scale.In parallel,data science and artificial intelligence(AI)are elegantly applied to break the diffraction limits of images recorded on a conventional microscope.These innovations have enabled very exciting applications,including the study of single particle catalysis,biomolecule trafficking inside a live cell,dynamic imaging of cellular organelles,and many others.展开更多
文摘Heterogeneous catalysis at the metal surface generally involves the transport of molecules through the interfacial water layer to access the surface,which is a rate-determining step at the nanoscale.In this study,taking the oxygen reduction reaction on a metal electrode in aqueous solution as an example,using accurate molecular dynamic simulations,we propose a novel long-range regulation strategy in which midinfrared stimulation(MIRS)with a frequency of approximately 1,000 cm^(-1)is applied to nonthermally induce the structural transition of interfacial water from an ordered to disordered state,facilitating the access of oxygen molecules to metal surfaces at room temperature and increasing the oxygen reduction activity 50-fold.Impressively,the theoretical prediction is confirmed by the experimental observation of a significant discharge voltage increase in zinc-air batteries under MIRS.This MIRS approach can be seamlessly integrated into existing strategies,offering a new approach for accelerating heterogeneous reactions and gas sensing within the interfacial water system.
基金the financial support of the Direction Générale de l’Armement(DGA)the ENS-Thales Chair,ANR project LIGNEDEMIR(ANR-18CE09-0035)+1 种基金FETOpen 2018–2020 Horizon 2020 projects cFLOW(Grant No.828893)QOMBS(Grant No.820419)and CNRS Renatech network.
文摘Free-space optical communication is a very promising alternative to fiber communication systems,in terms of ease of deployment and costs.Midinfrared light has several features of utter relevance for free-space applications:low absorption when propagating in the atmosphere even under adverse conditions,robustness of the wavefront during long-distance propagation,and absence of regulations and restrictions for this range of wavelengths.A proof-of-concept of high-speed transmission taking advantage of intersubband devices has recently been demonstrated,but this effort was limited by the short-distance optical path(up to 1 m).In this work,we study the possibility of building a long-range link using unipolar quantum optoelectronics.Two different detectors are used:an uncooled quantum cascade detector and a nitrogen-cooled quantum well-infrared photodetector.We evaluate the maximum data rate of our link in a back-to-back configuration before adding a Herriott cell to increase the length of the light path up to 31 m.By using pulse shaping,pre-and post-processing,we reach a record bitrate of 30 Gbit s−1 for both two-level(OOK)and four-level(PAM-4)modulation schemes for a 31-m propagation link and a bit error rate compatible with error-correction codes.
基金Japan Science and Technology Agency(JST)Japan Agency for Medical Research and Development(AMED)
文摘We demonstrated stable midinfrared(MIR) optical frequency comb at the 3.0 μm region with difference frequency generation pumped by a high power, Er-doped, ultrashort pulse fiber laser system. A soliton mode-locked161 MHz high repetition rate fiber laser using a single wall carbon nanotube was fabricated. The output pulse was amplified in an Er-doped single mode fiber amplifier, and a 1.1–2.2 μm wideband supercontinuum(SC) with an average power of 205 m W was generated in highly nonlinear fiber. The spectrogram of the generated SC was examined both experimentally and numerically. The generated SC was focused into a nonlinear crystal, and stable generation of MIR comb around the 3 μm wavelength region was realized.
基金supported by the National Natural Science Foundation of China(NSFC,22002123 and U1862111)Sichuan Science and Technology Program(2020YFH0118,2021JDGD0029 and 2021YFH0055)+6 种基金the Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLN201802)the Independent Research Fund Denmark-Nature Sciences(DFF-FNU,DFF-7014-00302)the Independent Research Fund Denmark-Sapere Aude starting grant(7026-00037A)the Research Fund for International Young Scientists from NSFC(21950410515)Swedish Research Council VR Starting Grant(2017-05337)the financial support from China Scholarship Council(201806320345,201908440313,201706170017,and 201806460021)Support from Swedish Energy Agency。
文摘Photoinduced carrier dynamical processes dominate the optical excitation properties of photocatalysts and further determine the photocatalytic performance.In addition,as the electrons generally possess a faster transfer rate than holes,hole transfer and accumulation are critical,and they play the key efficiency-limiting step during the photocatalytic process.Therefore,a comprehensive understanding of the dynamics of photogenerated holes and their determining factors in the photocatalytic system is highly essential to rationalize the full catalytic mechanism and develop highly efficient photocatalysts,which have not yet been revealed.In this work,the photoinduced charge carrier dynamics in InP/ZnS quantum dots(QDs)capped with longchain L-typed ligands(oleylamine)and inorganic ligands(sulfide ion(S^(2-)))were explored.Time-resolved photoluminescence and femtosecond transient-absorption spectroscopy unambiguously confirmed the ultrafast hole transfer from the InP core to S^(2-)ligands.Moreover,by probing the bleach of vibrational stretching of the ligands with transient midinfrared absorption spectroscopy,the hole transfer time was determined to be 4.2 ps.The injected holes are long-lived at the S^(2-) ligands(>4.5 ns),and they can remove electrostatically attached surfactants to compensate for the spatial charge redistribution.Finally,compared with other inorganic ligands such as Cl^(-) and PO_(4)^(3-),S^(2-) balances the ionic radii and net charge to ensure the optimal condition for charge transfer.Such observation rationalizes the excellent photocatalytic H_(2) evolution(213.6μmol mg^(-1) within 10 h)in InP/ZnS QDs capped with S^(2-) compared with those capped with other ligands and elucidates the role of surface ligands in the photocatalytic activity of colloidal QDs.
文摘GSMBE grown 1 84 micron wavelength InGaAs/InGaAsP/InP strained quantum well lasers are reported. Lasers with 800 micron long cavity and 40 micron wide planar electrical stripe have been operated under the pulsed regime at room temperature. At 20℃, the threshold current density is 3 8kA/cm 2 and the external different quantum efficiency is 9 3%.
文摘Acentral theme of chemical imaging is the visualization of chemistry in situ in functional materials and in vivo in a living system.To achieve this,technologies with exceptional detection sensitivity and spatial resolution are essential for resolving specific chemicals at the nanoscale.As we celebrate the 10th anniversary of the Nobel Prize in Chemistry awarded for super-resolved fluorescence microscopy,the field’s remarkable advancements become clear.Over the past 10 years,novel microscopies that break light diffraction limits continue to be invented.These include,for example,midinfrared photothermal microscopy that breaks the diffraction limit in IR imaging,and expansion microscopy that allows super-resolution fluorescence imaging on a conventional microscope.Meanwhile,researchers have much increased the speed of structural illumination microscopy(SIM)and single molecule localization microscopy(SMLM),and pushed the resolution limit of stimulated emission depletion(STED)microscopy to angstrom scale.In parallel,data science and artificial intelligence(AI)are elegantly applied to break the diffraction limits of images recorded on a conventional microscope.These innovations have enabled very exciting applications,including the study of single particle catalysis,biomolecule trafficking inside a live cell,dynamic imaging of cellular organelles,and many others.
