Understanding the behavior of matter at extreme pressures of the order of a megabar(Mbar)is essential to gain insight into various physical phenomena at macroscales—the formation of planets,young stars,and the cores ...Understanding the behavior of matter at extreme pressures of the order of a megabar(Mbar)is essential to gain insight into various physical phenomena at macroscales—the formation of planets,young stars,and the cores of super-Earths,and at microscales—damage to ceramic materials and high-pressure plastic transformation and phase transitions in solids.Under dynamic compression of solids up to Mbar pressures,even a solid with high strength exhibits plastic properties,causing the induced shock wave to split in two:an elastic precursor and a plastic shock wave.This phenomenon is described by theoretical models based on indirect measurements of material response.The advent of x-ray free-electron lasers(XFELs)has made it possible to use their ultrashort pulses for direct observations of the propagation of shock waves in solid materials by the method of phase-contrast radiography.However,there is still a lack of comprehensive data for verification of theoretical models of different solids.Here,we present the results of an experiment in which the evolution of the coupled elastic-plastic wave structure in diamond was directly observed and studied with submicrometer spatial resolution,using the unique capabilities of the x-ray free-electron laser(XFEL).The direct measurements allowed,for the first time,the fitting and validation of the 2D failure model for diamond in the range of several Mbar.Our experimental approach opens new possibilities for the direct verification and construction of equations of state of matter in the ultra-high-stress range,which are relevant to solving a variety of problems in high-energy-density physics.展开更多
X-ray absorption spectroscopy is a well-accepted diagnostic for experimental studies of warm dense matter.It requires a short-lived X-ray source of sufficiently high emissivity and without characteristic lines in the ...X-ray absorption spectroscopy is a well-accepted diagnostic for experimental studies of warm dense matter.It requires a short-lived X-ray source of sufficiently high emissivity and without characteristic lines in the spectral range of interest.In the present work,we discuss how to choose an optimum material and thickness to get a bright source in the wavelength range 2A–6A(∼2 keV to 6 keV)by considering relatively low-Z elements.We demonstrate that the highest emissivity of solid aluminum and silicon foil targets irradiated with a 1-ps high-contrast sub-kJ laser pulse is achieved when the target thickness is close to 10μm.An outer plastic layer can increase the emissivity even further.展开更多
Electrochemical CO_(2) reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily a...Electrochemical CO_(2) reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily accessible active sites for CO_(2) electroreduction remains challenging yet indispensable.In this work,a reliable poly(ethyleneimine)(PEI)-assisted strategy is developed to prepare a hollow carbon nanocomposite comprising a single-site Ni-modified carbon shell and confined Ni nanoparticles(NPs)(denoted as Ni@NHCS),where PEI not only functions as a mediator to induce the highly dispersed growth of Ni NPs within hollow carbon spheres,but also as a nitrogen precursor to construct highly active atomically-dispersed Ni-Nx sites.Benefiting from the unique structural properties of Ni@NHCS,the aggregation and exposure of Ni NPs can be effectively prevented,while the accessibility of abundant catalytically active Ni-Nx sites can be ensured.As a result,Ni@NHCS exhibits a high CO partial current density of 26.9 mA cm^(-2) and a Faradaic efficiency of 93.0% at-1.0 V vs.RHE,outperforming those of its PEI-free analog.Apart from the excellent activity and selectivity,the shell confinement effect of the hollow carbon sphere endows this catalyst with long-term stability.The findings here are anticipated to help understand the structure-activity relationship in Ni-based carbon catalyst systems for electrocatalytic CO_(2) reduction.Furthermore,the PEI-assisted synthetic concept is potentially applicable to the preparation of high-performance metal-based nanoconfined materials tailored for diverse energy conversion applications and beyond.展开更多
The generation of a plasma with an ultrahigh energy density of 1.2 GJ/cm^(3)(which corresponds to about 12 Gbar pressure) is investigated by irradiating thin stainless-steel foils with high-contrast femtosecond laser ...The generation of a plasma with an ultrahigh energy density of 1.2 GJ/cm^(3)(which corresponds to about 12 Gbar pressure) is investigated by irradiating thin stainless-steel foils with high-contrast femtosecond laser pulses with relativistic intensities of up to 10^(22) W/cm^(2).The plasma parameters are determined by X-ray spectroscopy.The results show that most of the laser energy is absorbed by the plasma at solid density,indicating that no pre-plasma is generated in the current experimental setup.展开更多
We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and ho...We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and homogeneity of targets to be driven by optical laser pulse.By developing X-ray imaging,based on the use of an LiF crystal detector,we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution(~1 mm)and across a field of view larger than some millimetres.This diagnostic can be used in situ,provides a very high dynamic range,has an extremely limited cost,and is relatively easy to be implemented in pump-probe experiments.The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser(SACLA)XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.展开更多
The physics of compressible turbulence in high energy density(HED) plasmas is an unchartered experimental area.Simulations of compressible and radiative flows relevant for astrophysics rely mainly on subscale paramete...The physics of compressible turbulence in high energy density(HED) plasmas is an unchartered experimental area.Simulations of compressible and radiative flows relevant for astrophysics rely mainly on subscale parameters. Therefore,we plan to perform turbulent hydrodynamics experiments in HED plasmas(TurboHEDP) in order to improve our understanding of such important phenomena for interest in both communities: laser plasma physics and astrophysics. We will focus on the physics of supernovae remnants which are complex structures subject to fluid instabilities such as the Rayleigh–Taylor and Kelvin–Helmholtz instabilities. The advent of megajoule laser facilities, like the National Ignition Facility and the Laser Megajoule, creates novel opportunities in laboratory astrophysics, as it provides unique platforms to study turbulent mixing flows in HED plasmas. Indeed, the physics requires accelerating targets over larger distances and longer time periods than previously achieved. In a preparatory phase, scaling from experiments at lower laser energies is used to guarantee the performance of future MJ experiments. This subscale experiments allow us to develop experimental skills and numerical tools in this new field of research, and are stepping stones to achieve our objectives on larger laser facilities. We review first in this paper recent advances in high energy density experiments devoted to laboratory astrophysics. Then we describe the necessary steps forward to commission an experimental platform devoted to turbulent hydrodynamics on a megajoule laser facility. Recent novel experimental results acquired on LULI2000, as well as supporting radiative hydrodynamics simulations, are presented. Together with the development of LiF detectors as transformative X-ray diagnostics, these preliminary results are promising on the way to achieve micrometric spatial resolution in turbulent HED physics experiments in the near future.展开更多
The development of reliable catalysts with both excellent activity and recyclability for carbon dioxide(CO_(2))hydrogenation is challenging.Herein,a ternary hybrid heterogeneous catalyst,involving mononuclear Ru compl...The development of reliable catalysts with both excellent activity and recyclability for carbon dioxide(CO_(2))hydrogenation is challenging.Herein,a ternary hybrid heterogeneous catalyst,involving mononuclear Ru complex,N,P-containing porous organic polymers(POPs),and mesoporous hollow carbon spheres(Ru^(3+)-POPs@MHCS)is reported for CO_(2)hydrogenation to formate.Based on comprehensive structural analyses,we demonstrated that Ru^(3+)-POPs were successfully immobilized within MHCS.The optimized Ru^(3+)-0.5POPs@MHCS catalyst,which was obtained with about 5 wt.%Ru^(3+)and 0.5 mmol POPs polymers confined into 0.3 g MHCS,exhibited high catalytic activity for CO_(2)hydrogenation to formate(turnover number(TON)>1,200 for 24 h under mild reaction conditions(4.0 MPa,120℃))and improved durability,compared to Ru^(3+)catalysts without POPs polymers(Ru^(3+)-MHCS)and unencapsulated MHCS(Ru^(3+)-0.5POPs)catalysts.The improved catalytic performance is attributed to the high surface area and large pore volume of MHCS which favors dispersion and stabilization of Ru^(3+)-POPs.Furthermore,the MHCS and POPs showed high CO_(2)adsorption ability.Ru^(3+)-POPs encapsulated into MHCS reduces the activation energy barrier for CO_(2)hydrogenation to formate.展开更多
The effect of crystallization of polymeric carbon nitride(PCN)on the photocatalytic CO_(2)reduction activity of a three-component hybrid comprising a Ru(II)binuclear complex(RuRu),Ag nanoparticles,and PCN,was investig...The effect of crystallization of polymeric carbon nitride(PCN)on the photocatalytic CO_(2)reduction activity of a three-component hybrid comprising a Ru(II)binuclear complex(RuRu),Ag nanoparticles,and PCN,was investigated.Crystallized carbon nitride(CCN)obtained by heat treatment of PCN in a eutectic LiCl-KCl mixture was a much better hybrid photocatalyst component than the poorly crystallized PCN.The photocatalytic activity of CCN was dependent on the temperature of the LiCl-KCl treatment:Increasing the treatment temperature improved the photocatalytic activity as much as five-fold;however,treatment at elevated temperatures(>798 K)had a detrimental effect.Also,a substantial PCN crystallization effect was promoted by the construction of another hybrid photocatalyst from a mononuclear Ru(II)complex catalyst.Time-resolved microwave photoconductivity measurements revealed a good correlation between the photocatalytic activity and the photoconductivity-charge carrier lifetime product in the CCN samples heated at milder temperatures(≤798 K).For CCN specimens heated at higher temperatures,appreciable electron accumulation was observed during the photocatalytic reaction,indicating that the accumulated electrons could not participate in the CO_(2)reduction reaction.Thus,the crystallization of PCN at milder temperatures improved the mobility and lifetime of photogenerated charge carriers,thereby contributing to enhanced photocatalytic activity toward CO_(2)reduction.展开更多
Knowledge about electronic structures is important to gain an understanding of the unique functional properties of diradicaloids.In this study,we synthesized and characterized a diradicaloid in which two phenalenyl ra...Knowledge about electronic structures is important to gain an understanding of the unique functional properties of diradicaloids.In this study,we synthesized and characterized a diradicaloid in which two phenalenyl radical sites are coupled antiferromagnetically via a through-space interaction.The results of quantum chemical,physicochemical(^(1)H NMR,electronic absorption,cyclic voltammetry,SQUID,ESR),and chemical reactivity studies show that this diradicaloid has singlet diradical character.An assessment of the nature of the bonding interaction between two radical sites in this species using DFT calculations demonstrates that a small spatial overlap between the two SOMOs in this diradicaloid provides an efficient electron exchange path for the singlet state to be substantially lower in energy than the triplet state.展开更多
Since the discovery of the triphenylmethyl(trityl)cation 120 years ago,a variety of aromatic cations having various colors and luminescence properties have been rigorously studied.Many,differently substituted trityl c...Since the discovery of the triphenylmethyl(trityl)cation 120 years ago,a variety of aromatic cations having various colors and luminescence properties have been rigorously studied.Many,differently substituted trityl cations have been synthesized,and their optical properties have been elucidated.However,the optical properties of the parent,non-substituted and highly reactive trityl cation,which was observed to be very weakly luminescent,have not been subjected to detailed investigation.In the effort described herein,we explored the optical nature of non-substituted trityl hexafluorophosphate(PF_(6))in the crystalline state.Trityl PF_(6) was found to exist as two crystal polymorphs including a yellow(Y)and an orange(O)form.Moreover,we observed that these crystalline forms display crystalline-state emission with different colors.The results of X-ray crystallographic analysis showed that the two polymorphs have totally different molecular packing arrangements.Furthermore,an investigation of their optical properties revealed that the O-crystal undergoes a distinct color change to yellow upon cooling as a consequence of a change in the nature of the charge transfer interaction between the cation and PF6 anion,and that both the Y-and O-crystal exhibit phosphorescence.展开更多
Fluorescence microscopy enables the visualization of cellular morphology,molecular distribution,ion distribution,and their dynamic behaviors during biological processes.Enhancing the signal-to-noise ratio(SNR)in fluor...Fluorescence microscopy enables the visualization of cellular morphology,molecular distribution,ion distribution,and their dynamic behaviors during biological processes.Enhancing the signal-to-noise ratio(SNR)in fluorescence imaging improves the quantification accuracy and spatial resolution;however,achieving high SNR at fast image acquisition rates,which is often required to observe cellular dynamics,still remains a challenge.In this study,we developed a technique to rapidly freeze biological cells in milliseconds during optical microscopy observation.Compared to chemical fixation,rapid freezing provides rapid immobilization of samples while more effectively preserving the morphology and conditions of cells.This technique combines the advantages of both live-cell and cryofixation microscopy,i.e.,temporal dynamics and high SNR snapshots of selected moments,and is demonstrated by fluorescence and Raman microscopy with high spatial resolution and quantification under low temperature conditions.Furthermore,we also demonstrated that intracellular calcium dynamics can be frozen rapidly and visualized using fluorescent ion indicators,suggesting that ion distribution and conformation of the probe molecules can be fixed both spatially and temporally.These results confirmed that our technique can time-deterministically suspend and visualize cellular dynamics while preserving molecular and ionic states,indicating the potential to provide detailed insights into sample dynamics with improved spatial resolution and temporal accuracy in observations.展开更多
Raman imaging has the capability to provide unlabeled,spatially aware analysis of chemical components,with no a priori assumptions.Several lifestyle diseases such as nonalcoholic steatohepatitis(NASH)can appear in the...Raman imaging has the capability to provide unlabeled,spatially aware analysis of chemical components,with no a priori assumptions.Several lifestyle diseases such as nonalcoholic steatohepatitis(NASH)can appear in the liver as changes in the nature,abundance,and distribution of lipids,proteins,and other biomolecules and are detectable by Raman imaging.In order to identify which of these liver-associated changes occur as a direct result of the diet and which are secondary effects,we developed correlative imaging and analysis of diet and liver samples.Oleic acid was found to be a direct contributor to NASH liver composition,whereas protein and collagen distributions were found to be affected in a manner consistent with early fibrotic transformation,as a secondary consequence of the high-fat diet.展开更多
Light-driven actuators are widely used for smart devices such as soft robots.One of the main challenges for actuators is achieving rapid responsiveness,in addition to ensuring favorable mechanical properties.Herein,we...Light-driven actuators are widely used for smart devices such as soft robots.One of the main challenges for actuators is achieving rapid responsiveness,in addition to ensuring favorable mechanical properties.Herein,we focused on photoresponsive polyurethane(CD-Azo-PU)based on controlling the crystallization of the hard segments in polyurethane(PU)by complexation between azobenzene(Azo)and cyclodextrins(CDs).CD-Azo-PU incorporated polyurethane as the main chain and a 1:2 inclusion complex between Azo andγCD as a movable crosslink point.Upon ultraviolet light(UV,λ=365 nm)irradiation,the photoresponsiveness of CD-Azo-PU bent toward the light source(defined as positive),while that of the linear Azo polyurethane(Azo-LPU)without peracetylatedγ-cyclodextrin diol(TAcγCD-diOH)as a movable crosslinker bent in the direction opposite the light source.The bending rates were determined to be 0.25°/s for CD-Azo-PU and 0.083◦/s for Azo-LPU,indicating that the bending rate for CD-Azo-PU was faster than that for Azo-LPU.By incorporating movable crosslinks into CD-Azo-PU,we successfully achieved specific photoresponsive actuation with an enhanced rate.展开更多
Tight focusing with very small f-numbers is necessary to achieve the highest at-focus irradiances.However,tight focusing imposes strong demands on precise target positioning in-focus to achieve the highest on-target i...Tight focusing with very small f-numbers is necessary to achieve the highest at-focus irradiances.However,tight focusing imposes strong demands on precise target positioning in-focus to achieve the highest on-target irradiance We describe several near-infrared,visible,ultraviolet and soft and hard X-ray diagnostics employed in a~10^(22)W/cm^(2)laser±plasma experiment.We used nearly 10 J total energy femtosecond laser pulses focused into an approximately1.3-μm focal spot on 5±20μm thick stainless-steel targets.We discuss the applicability of these diagnostics to determine the best in-focus target position with approximately 5μm accuracy(i.e.,around half of the short Rayleigh length)and show that several diagnostics(in particular,3ωreflection and on-axis hard X-rays)can ensure this accuracy.We demonstrated target positioning within several micrometers from the focus,ensuring over 80%of the ideal peak laser intensity on-target.Our approach is relatively fast(it requires 10±20 laser shots)and does not rely on the coincidence of low-power and high-power focal planes.展开更多
X-ray absorption spectroscopy is proposed as a method for studying the heating of solid-density matter excited by secondary X-ray radiation from a relativistic laser-produced plasma. The method was developed and appli...X-ray absorption spectroscopy is proposed as a method for studying the heating of solid-density matter excited by secondary X-ray radiation from a relativistic laser-produced plasma. The method was developed and applied to experiments involving thin silicon foils irradiated by 0.5–1.5 ps duration ultrahigh contrast laser pulses at intensities between 0.5 × 10^(20) and 2.5 × 10^(20) W∕cm^2. The electron temperature of the material at the rear side of the target is estimated to be in the range of 140–300 eV. The diagnostic approach enables the study of warm dense matter states with low self-emissivity.展开更多
The synthesis of gold nanoparticles(Au NPs)was carried out by utilising the pulsed laser ablation in liquids(PLAL)method with a microchip laser(MCL)system.This portable system features low power consumption and a gian...The synthesis of gold nanoparticles(Au NPs)was carried out by utilising the pulsed laser ablation in liquids(PLAL)method with a microchip laser(MCL)system.This portable system features low power consumption and a giant-pulse laser.Aqueous solutions with and without the surfactant poly(N-vinyl-2-pyrrolidone)(PVP)were used for laser ablation of a bulk gold rod to achieve the successful formation of a colloidal solution of Au NPs.The gas bubbles formed by heating the aqueous medium around the surface of the gold target significantly reduced the efficiency of Au NP ablation.This effect was more pronounced and prolonged in high-viscosity solutions,hindering energy transfer from subsequent laser pulses to the target.Additionally,it was suggested that the chain length of PVP does not affect either the size of the Au NPs or the ablation efficiency.Videography experiments were conducted to explore the ablation mechanism employed by the MCL system.The relatively short pulse duration of the MCL system may contribute to the formation of NPs with consistent size,which were suppressed to grow in significantly smaller cavitation bubbles with short lifetimes.展开更多
基金We thank the technical staff of SACLA for their support during the experiment.The experiment was performed at BL3 of SACLA with the approval of the Japan Synchrotron Radiation Research Institute(Proposal Nos.2021A8004 and 2021B8002).The high-power drive laser installed in SACLA EH5 was developed with the cooperation of Hamamatsu Photonics.The installation of diffractive optical elements to improve the smoothness of the drive laser-pattern was supported by the SACLA Basic Development ProgramThe work was carried out with the financial support of the Russian Federation represented by the Ministry of Science and Higher Education of the Russian Federation(Grant No.075-15-2021-1352)This work was supported by KAKENHI(Grant Nos.17K05729 and 21K03499)from the Japan Society for the Promotion of Science(JSPS).
文摘Understanding the behavior of matter at extreme pressures of the order of a megabar(Mbar)is essential to gain insight into various physical phenomena at macroscales—the formation of planets,young stars,and the cores of super-Earths,and at microscales—damage to ceramic materials and high-pressure plastic transformation and phase transitions in solids.Under dynamic compression of solids up to Mbar pressures,even a solid with high strength exhibits plastic properties,causing the induced shock wave to split in two:an elastic precursor and a plastic shock wave.This phenomenon is described by theoretical models based on indirect measurements of material response.The advent of x-ray free-electron lasers(XFELs)has made it possible to use their ultrashort pulses for direct observations of the propagation of shock waves in solid materials by the method of phase-contrast radiography.However,there is still a lack of comprehensive data for verification of theoretical models of different solids.Here,we present the results of an experiment in which the evolution of the coupled elastic-plastic wave structure in diamond was directly observed and studied with submicrometer spatial resolution,using the unique capabilities of the x-ray free-electron laser(XFEL).The direct measurements allowed,for the first time,the fitting and validation of the 2D failure model for diamond in the range of several Mbar.Our experimental approach opens new possibilities for the direct verification and construction of equations of state of matter in the ultra-high-stress range,which are relevant to solving a variety of problems in high-energy-density physics.
基金The study was supported financially by the Russian Foundation for Basic Research(Grant No.20-02-00790)the Joint Institute for High Temperatures of the Russian Academy of Sciences(Topic Grant No.01201357846)The UK team received financial support from the Engineering and Physical Sciences Research Council(Grant Nos.EP/L01663X/1 and EP/H012605/1).
文摘X-ray absorption spectroscopy is a well-accepted diagnostic for experimental studies of warm dense matter.It requires a short-lived X-ray source of sufficiently high emissivity and without characteristic lines in the spectral range of interest.In the present work,we discuss how to choose an optimum material and thickness to get a bright source in the wavelength range 2A–6A(∼2 keV to 6 keV)by considering relatively low-Z elements.We demonstrate that the highest emissivity of solid aluminum and silicon foil targets irradiated with a 1-ps high-contrast sub-kJ laser pulse is achieved when the target thickness is close to 10μm.An outer plastic layer can increase the emissivity even further.
文摘Electrochemical CO_(2) reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily accessible active sites for CO_(2) electroreduction remains challenging yet indispensable.In this work,a reliable poly(ethyleneimine)(PEI)-assisted strategy is developed to prepare a hollow carbon nanocomposite comprising a single-site Ni-modified carbon shell and confined Ni nanoparticles(NPs)(denoted as Ni@NHCS),where PEI not only functions as a mediator to induce the highly dispersed growth of Ni NPs within hollow carbon spheres,but also as a nitrogen precursor to construct highly active atomically-dispersed Ni-Nx sites.Benefiting from the unique structural properties of Ni@NHCS,the aggregation and exposure of Ni NPs can be effectively prevented,while the accessibility of abundant catalytically active Ni-Nx sites can be ensured.As a result,Ni@NHCS exhibits a high CO partial current density of 26.9 mA cm^(-2) and a Faradaic efficiency of 93.0% at-1.0 V vs.RHE,outperforming those of its PEI-free analog.Apart from the excellent activity and selectivity,the shell confinement effect of the hollow carbon sphere endows this catalyst with long-term stability.The findings here are anticipated to help understand the structure-activity relationship in Ni-based carbon catalyst systems for electrocatalytic CO_(2) reduction.Furthermore,the PEI-assisted synthetic concept is potentially applicable to the preparation of high-performance metal-based nanoconfined materials tailored for diverse energy conversion applications and beyond.
基金carried out within the framework of Program 10 “Experimental laboratory astrophysics and geophysics,NCPM.”。
文摘The generation of a plasma with an ultrahigh energy density of 1.2 GJ/cm^(3)(which corresponds to about 12 Gbar pressure) is investigated by irradiating thin stainless-steel foils with high-contrast femtosecond laser pulses with relativistic intensities of up to 10^(22) W/cm^(2).The plasma parameters are determined by X-ray spectroscopy.The results show that most of the laser energy is absorbed by the plasma at solid density,indicating that no pre-plasma is generated in the current experimental setup.
基金The XFEL experiments were performed at the BL3 of SACLA with the approval of the Japan Synchrotron Radiation Research Institute(JASRI)(Proposals Nos.2014A8045,and 2014B8068)This research was partially supported by grants from Grants-in-Aid for Scientific Research(Kakenhi Grant Nos.15H02153 and 17K05729)+1 种基金the Core-to-Core Program on International Alliance for Material Science in Extreme States with High Power Laser of the Japan Society for the Promotion of Science(JSPS),from the X-ray Free Electron Laser Priority Strategy Program of the MEXT,contract 12005014,and within the state assignment of FASO of Russia(theme N01201357846)The part of work was supported by the Agence Nationale de la Recherche in the frame of the ANR project TurboHEDP(ANR-15-CE30-0011).
文摘We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and homogeneity of targets to be driven by optical laser pulse.By developing X-ray imaging,based on the use of an LiF crystal detector,we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution(~1 mm)and across a field of view larger than some millimetres.This diagnostic can be used in situ,provides a very high dynamic range,has an extremely limited cost,and is relatively easy to be implemented in pump-probe experiments.The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser(SACLA)XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.
基金supported by the Agence Nationale de la Recherche under the ANR project TurboHEDP(ANR-15-CE30-0011)
文摘The physics of compressible turbulence in high energy density(HED) plasmas is an unchartered experimental area.Simulations of compressible and radiative flows relevant for astrophysics rely mainly on subscale parameters. Therefore,we plan to perform turbulent hydrodynamics experiments in HED plasmas(TurboHEDP) in order to improve our understanding of such important phenomena for interest in both communities: laser plasma physics and astrophysics. We will focus on the physics of supernovae remnants which are complex structures subject to fluid instabilities such as the Rayleigh–Taylor and Kelvin–Helmholtz instabilities. The advent of megajoule laser facilities, like the National Ignition Facility and the Laser Megajoule, creates novel opportunities in laboratory astrophysics, as it provides unique platforms to study turbulent mixing flows in HED plasmas. Indeed, the physics requires accelerating targets over larger distances and longer time periods than previously achieved. In a preparatory phase, scaling from experiments at lower laser energies is used to guarantee the performance of future MJ experiments. This subscale experiments allow us to develop experimental skills and numerical tools in this new field of research, and are stepping stones to achieve our objectives on larger laser facilities. We review first in this paper recent advances in high energy density experiments devoted to laboratory astrophysics. Then we describe the necessary steps forward to commission an experimental platform devoted to turbulent hydrodynamics on a megajoule laser facility. Recent novel experimental results acquired on LULI2000, as well as supporting radiative hydrodynamics simulations, are presented. Together with the development of LiF detectors as transformative X-ray diagnostics, these preliminary results are promising on the way to achieve micrometric spatial resolution in turbulent HED physics experiments in the near future.
基金supported by JSPS KAKENHI(Nos.18K14056 and 19H00838)JST,PRESTO(No.JPMJPR19T3)+3 种基金Japan.A part of this work was supported by the cooperative research program of“Network Joint Research Center for Materials and Devices”(No.20211069).support of the International Joint Research Promotion Program at Osaka University.G.X.Y.gratefully acknowledges the financial support from the China Scholarship Council(No.201808310132)Y.K.,K.M.,and H.Y.thank the Elements Strategy Initiative of MEXT(No.JPMXP0112101003)Japan.The synchrotron radiation experiments for XAFS measurement were performed at the BL01B1 beamline in SPring-8 with approval from JASRI(Nos.2019B1114 and 2020A1064).
文摘The development of reliable catalysts with both excellent activity and recyclability for carbon dioxide(CO_(2))hydrogenation is challenging.Herein,a ternary hybrid heterogeneous catalyst,involving mononuclear Ru complex,N,P-containing porous organic polymers(POPs),and mesoporous hollow carbon spheres(Ru^(3+)-POPs@MHCS)is reported for CO_(2)hydrogenation to formate.Based on comprehensive structural analyses,we demonstrated that Ru^(3+)-POPs were successfully immobilized within MHCS.The optimized Ru^(3+)-0.5POPs@MHCS catalyst,which was obtained with about 5 wt.%Ru^(3+)and 0.5 mmol POPs polymers confined into 0.3 g MHCS,exhibited high catalytic activity for CO_(2)hydrogenation to formate(turnover number(TON)>1,200 for 24 h under mild reaction conditions(4.0 MPa,120℃))and improved durability,compared to Ru^(3+)catalysts without POPs polymers(Ru^(3+)-MHCS)and unencapsulated MHCS(Ru^(3+)-0.5POPs)catalysts.The improved catalytic performance is attributed to the high surface area and large pore volume of MHCS which favors dispersion and stabilization of Ru^(3+)-POPs.Furthermore,the MHCS and POPs showed high CO_(2)adsorption ability.Ru^(3+)-POPs encapsulated into MHCS reduces the activation energy barrier for CO_(2)hydrogenation to formate.
基金the National Natural Science Foundation of China(grant no.22311540011)the Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research(JSPS KAKENHI+2 种基金grant nos.JPJSBP120237406,JP22H05148,JP23H04626,and JP20H05836)supported by the Japan Science and Technology Support for Pioneering Research Initiated by the Next Generation(JST SPRINGgrant no.JPMJSP2106).
文摘The effect of crystallization of polymeric carbon nitride(PCN)on the photocatalytic CO_(2)reduction activity of a three-component hybrid comprising a Ru(II)binuclear complex(RuRu),Ag nanoparticles,and PCN,was investigated.Crystallized carbon nitride(CCN)obtained by heat treatment of PCN in a eutectic LiCl-KCl mixture was a much better hybrid photocatalyst component than the poorly crystallized PCN.The photocatalytic activity of CCN was dependent on the temperature of the LiCl-KCl treatment:Increasing the treatment temperature improved the photocatalytic activity as much as five-fold;however,treatment at elevated temperatures(>798 K)had a detrimental effect.Also,a substantial PCN crystallization effect was promoted by the construction of another hybrid photocatalyst from a mononuclear Ru(II)complex catalyst.Time-resolved microwave photoconductivity measurements revealed a good correlation between the photocatalytic activity and the photoconductivity-charge carrier lifetime product in the CCN samples heated at milder temperatures(≤798 K).For CCN specimens heated at higher temperatures,appreciable electron accumulation was observed during the photocatalytic reaction,indicating that the accumulated electrons could not participate in the CO_(2)reduction reaction.Thus,the crystallization of PCN at milder temperatures improved the mobility and lifetime of photogenerated charge carriers,thereby contributing to enhanced photocatalytic activity toward CO_(2)reduction.
基金the JSPS for KAKENHI funding(Grant No.JP21H01918 and JP20K21194)a Grant-in-Aid for Transformative Research Areas(A)“Condensed Conjugation”(JSPS for KAKENHI funding Grant No.JP20H05865)from MEXT,Japan.
文摘Knowledge about electronic structures is important to gain an understanding of the unique functional properties of diradicaloids.In this study,we synthesized and characterized a diradicaloid in which two phenalenyl radical sites are coupled antiferromagnetically via a through-space interaction.The results of quantum chemical,physicochemical(^(1)H NMR,electronic absorption,cyclic voltammetry,SQUID,ESR),and chemical reactivity studies show that this diradicaloid has singlet diradical character.An assessment of the nature of the bonding interaction between two radical sites in this species using DFT calculations demonstrates that a small spatial overlap between the two SOMOs in this diradicaloid provides an efficient electron exchange path for the singlet state to be substantially lower in energy than the triplet state.
基金JSPSKAKENHI Grant-in-Aid for Scientific Research(C),Grant/Award Number:JP20K05475(Tomohiko Nishiuchi)Scientific Research(B),Grant/Award Number:JP21H01887(Kenji Kamada)。
文摘Since the discovery of the triphenylmethyl(trityl)cation 120 years ago,a variety of aromatic cations having various colors and luminescence properties have been rigorously studied.Many,differently substituted trityl cations have been synthesized,and their optical properties have been elucidated.However,the optical properties of the parent,non-substituted and highly reactive trityl cation,which was observed to be very weakly luminescent,have not been subjected to detailed investigation.In the effort described herein,we explored the optical nature of non-substituted trityl hexafluorophosphate(PF_(6))in the crystalline state.Trityl PF_(6) was found to exist as two crystal polymorphs including a yellow(Y)and an orange(O)form.Moreover,we observed that these crystalline forms display crystalline-state emission with different colors.The results of X-ray crystallographic analysis showed that the two polymorphs have totally different molecular packing arrangements.Furthermore,an investigation of their optical properties revealed that the O-crystal undergoes a distinct color change to yellow upon cooling as a consequence of a change in the nature of the charge transfer interaction between the cation and PF6 anion,and that both the Y-and O-crystal exhibit phosphorescence.
基金supported by JST-CREST and JST COI-NEXT program under Grant number JPMJCR1925 and JPMJPF2009supported by JST SPRING under Grant number JPMJSP2138,Deutsche Forschungsgemeinschaft SFB1278(TP C04)+1 种基金the Leibniz Association(Leibniz Science Campus,InfectoOptics,HotAim 2.0)supported by Janelia Research Campus,Howard Hughes Medical Institute.
文摘Fluorescence microscopy enables the visualization of cellular morphology,molecular distribution,ion distribution,and their dynamic behaviors during biological processes.Enhancing the signal-to-noise ratio(SNR)in fluorescence imaging improves the quantification accuracy and spatial resolution;however,achieving high SNR at fast image acquisition rates,which is often required to observe cellular dynamics,still remains a challenge.In this study,we developed a technique to rapidly freeze biological cells in milliseconds during optical microscopy observation.Compared to chemical fixation,rapid freezing provides rapid immobilization of samples while more effectively preserving the morphology and conditions of cells.This technique combines the advantages of both live-cell and cryofixation microscopy,i.e.,temporal dynamics and high SNR snapshots of selected moments,and is demonstrated by fluorescence and Raman microscopy with high spatial resolution and quantification under low temperature conditions.Furthermore,we also demonstrated that intracellular calcium dynamics can be frozen rapidly and visualized using fluorescent ion indicators,suggesting that ion distribution and conformation of the probe molecules can be fixed both spatially and temporally.These results confirmed that our technique can time-deterministically suspend and visualize cellular dynamics while preserving molecular and ionic states,indicating the potential to provide detailed insights into sample dynamics with improved spatial resolution and temporal accuracy in observations.
基金funded by the Japan Society for the Promotion of Science(JSPS)through the Funding Program for World-Leading Innovative R&D on Science and Technology(FIRST Program)the JSPS World Premier International Research Center Initiative Funding Programthe Uehara Memorial Foundation.S.A.acknowledges funding from JSPS KAKENHI Grant-in-Aid for Scientific Research S(20H05693).
文摘Raman imaging has the capability to provide unlabeled,spatially aware analysis of chemical components,with no a priori assumptions.Several lifestyle diseases such as nonalcoholic steatohepatitis(NASH)can appear in the liver as changes in the nature,abundance,and distribution of lipids,proteins,and other biomolecules and are detectable by Raman imaging.In order to identify which of these liver-associated changes occur as a direct result of the diet and which are secondary effects,we developed correlative imaging and analysis of diet and liver samples.Oleic acid was found to be a direct contributor to NASH liver composition,whereas protein and collagen distributions were found to be affected in a manner consistent with early fibrotic transformation,as a secondary consequence of the high-fat diet.
基金MEXT of Japan,Grant/Award Numbers:JP19H05714,JP19H05721Core Research for Evolutional Science and Technology(CREST),Grant/Award Number:JPMJCR22L4+4 种基金Establishment of university fellowships toward the creation of science technology innovation,Grant/Award Number:JPMJFS2125Iketani Science and Technology Foundation,Grant/Award Numbers:0341026-A,0351026-AAsahi Glass FoundationYazaki Memorial Foundation for ScienceCOI-NEXT program,Grant/Award Number:JPMJPF2218。
文摘Light-driven actuators are widely used for smart devices such as soft robots.One of the main challenges for actuators is achieving rapid responsiveness,in addition to ensuring favorable mechanical properties.Herein,we focused on photoresponsive polyurethane(CD-Azo-PU)based on controlling the crystallization of the hard segments in polyurethane(PU)by complexation between azobenzene(Azo)and cyclodextrins(CDs).CD-Azo-PU incorporated polyurethane as the main chain and a 1:2 inclusion complex between Azo andγCD as a movable crosslink point.Upon ultraviolet light(UV,λ=365 nm)irradiation,the photoresponsiveness of CD-Azo-PU bent toward the light source(defined as positive),while that of the linear Azo polyurethane(Azo-LPU)without peracetylatedγ-cyclodextrin diol(TAcγCD-diOH)as a movable crosslinker bent in the direction opposite the light source.The bending rates were determined to be 0.25°/s for CD-Azo-PU and 0.083◦/s for Azo-LPU,indicating that the bending rate for CD-Azo-PU was faster than that for Azo-LPU.By incorporating movable crosslinks into CD-Azo-PU,we successfully achieved specific photoresponsive actuation with an enhanced rate.
基金financial support from ELI-Beamlinesproject Advanced Research using High Intensity Laser Produced Photons and Particles(ADONIS)(Project No.CZ.02.1.01/0.0/0.0/16_019/0000789)from the European Regional Development Fund+5 种基金QST-IRIthe QST President’s Strategic Grant(Creative Research)JSPS KAKENHI JP17F17811,JP19KK0355,JP19H00669 and JP22H01239the Czech Ministry of EducationYouth and Sports(CMEYS)for the financial support of the project number LM2023068partly supported by JSPS KAKENHI Grant No.JP23H01151。
文摘Tight focusing with very small f-numbers is necessary to achieve the highest at-focus irradiances.However,tight focusing imposes strong demands on precise target positioning in-focus to achieve the highest on-target irradiance We describe several near-infrared,visible,ultraviolet and soft and hard X-ray diagnostics employed in a~10^(22)W/cm^(2)laser±plasma experiment.We used nearly 10 J total energy femtosecond laser pulses focused into an approximately1.3-μm focal spot on 5±20μm thick stainless-steel targets.We discuss the applicability of these diagnostics to determine the best in-focus target position with approximately 5μm accuracy(i.e.,around half of the short Rayleigh length)and show that several diagnostics(in particular,3ωreflection and on-axis hard X-rays)can ensure this accuracy.We demonstrated target positioning within several micrometers from the focus,ensuring over 80%of the ideal peak laser intensity on-target.Our approach is relatively fast(it requires 10±20 laser shots)and does not rely on the coincidence of low-power and high-power focal planes.
基金Russian Science Foundation(RSF)(17-72-20272)Science and Technology Facilities Council(STFC)(EP/L000644/1)+3 种基金Engineering and Physical Sciences Research Council(EPSRC)(EP/L01663X/1)Los Alamos National Laboratory(LANL)National Nuclear Security Administration(NNSA)U.S.Department of Energy(DOE)(DE-AC5206NA25396)
文摘X-ray absorption spectroscopy is proposed as a method for studying the heating of solid-density matter excited by secondary X-ray radiation from a relativistic laser-produced plasma. The method was developed and applied to experiments involving thin silicon foils irradiated by 0.5–1.5 ps duration ultrahigh contrast laser pulses at intensities between 0.5 × 10^(20) and 2.5 × 10^(20) W∕cm^2. The electron temperature of the material at the rear side of the target is estimated to be in the range of 140–300 eV. The diagnostic approach enables the study of warm dense matter states with low self-emissivity.
基金supported by JSPS KAKENHI(JP19K22187)Foundation for the Promotion of Science&Engineering for financial supportthe Japan International Cooperation Agency(JICA)and Otsuka Toshimi Scholarship Foundation(21-S58 and 22-S30)for kindly providing scholarships.
文摘The synthesis of gold nanoparticles(Au NPs)was carried out by utilising the pulsed laser ablation in liquids(PLAL)method with a microchip laser(MCL)system.This portable system features low power consumption and a giant-pulse laser.Aqueous solutions with and without the surfactant poly(N-vinyl-2-pyrrolidone)(PVP)were used for laser ablation of a bulk gold rod to achieve the successful formation of a colloidal solution of Au NPs.The gas bubbles formed by heating the aqueous medium around the surface of the gold target significantly reduced the efficiency of Au NP ablation.This effect was more pronounced and prolonged in high-viscosity solutions,hindering energy transfer from subsequent laser pulses to the target.Additionally,it was suggested that the chain length of PVP does not affect either the size of the Au NPs or the ablation efficiency.Videography experiments were conducted to explore the ablation mechanism employed by the MCL system.The relatively short pulse duration of the MCL system may contribute to the formation of NPs with consistent size,which were suppressed to grow in significantly smaller cavitation bubbles with short lifetimes.
