Ferroelectric polymer nanocomposites possess exceptional electric properties with respect to the two otherwise uniform phases,which is commonly attributed to the critical role of the matrix-particle interfacial region...Ferroelectric polymer nanocomposites possess exceptional electric properties with respect to the two otherwise uniform phases,which is commonly attributed to the critical role of the matrix-particle interfacial region.However,the structure-property correlation of the interface remains unestablished,and thus,the design of ferroelectric polymer nanocompos-ite has largely relied on the trial-and-error method.Here,a strategy that combines multi-mode scanning probe microscopy-based electrical charac-terization and nano-infrared spectroscopy is developed to unveil the local structure-property correlation of the interface in ferroelectric polymer nano-composites.The results show that the type of surface modifiers decorated on the nanoparticles can significantly influence the local polar-phase content and the piezoelectric effect of the polymer matrix surrounding the nano-particles.The strongly coupled polar-phase content and piezoelectric effect measured directly in the interfacial region as well as the computed bonding energy suggest that the property enhancement originates from the formation of hydrogen bond between the surface modifiers and the ferroelectric polymer.It is also directly detected that the local domain size of the ferroelectric polymer can impact the energy level and distribution of charge traps in the interfacial region and eventually influence the local dielectric strength.展开更多
The microscopic physical properties of Hardened Cement Paste (HCP) surfaces were evaluated by using Scanning Probe Microscopy (SPM). The cement pastes were cured under a hydrostatic pressure of 400 MPa and the contact...The microscopic physical properties of Hardened Cement Paste (HCP) surfaces were evaluated by using Scanning Probe Microscopy (SPM). The cement pastes were cured under a hydrostatic pressure of 400 MPa and the contacting surfaces with a slide glass during the curing were studied. Scanning Electron Microscope (SEM) observation at a magnification of 7000 revealed smooth surfaces with no holes. The surface roughness calculated from the SPM measurement was 4 nm. The surface potential and the frictional force measured by SPM were uniform throughout the measured area 24 h after the curing. However, spots of low surface potential and stains of low frictional force and low viscoelasticity were observed one month after curing. This change was attributed to the carbonation of hydrates.展开更多
In this work,we investigate cross-sectional sample preparation for atomic force microscopy and general scanning probe microscopy(SPM)characterization.In light of traditional cross-sectional sample preparation solution...In this work,we investigate cross-sectional sample preparation for atomic force microscopy and general scanning probe microscopy(SPM)characterization.In light of traditional cross-sectional sample preparation solutions for transmission electron microscopy,mechanical polishing and focused ion beam(FIB)milling have been employed to prepare cross-sectional samples for SPM.We present an optimized solution for thin films and oxide heterostructures that allows for examining the prepared surfaces using various SPM techniques.In particular,post-cleaning after FIB milling is shown to be crucial and precision ion polishing was conducted to remove rough layers on mechanically polished samples.We also study SPM mechanical milling to remove amorphous layers on FIB-milled samples.Consequently,a reliable solution for making cross sections suitable for SPM has been achieved providing a useful methodology that can also be employed for other material systems with different hardness,such as polymers and metals.展开更多
Carbon,as an indispensable chemical element on Earth,has diverse covalent bonding ability,which enables construction of extensive pivotal carbon-based structures in multiple scientific fields.The extraordinary physico...Carbon,as an indispensable chemical element on Earth,has diverse covalent bonding ability,which enables construction of extensive pivotal carbon-based structures in multiple scientific fields.The extraordinary physicochemical properties presented by pioneering synthetic carbon allotropes,typically including fullerenes,carbon nanotubes,and graphene,have stimulated broad interest in fabrication of carbon-based nanostructures and nanomaterials.Accurate regulation of topology,size,and shape,as well as controllably embedding target sp^(n)-hybridized carbons in molecular skeletons,is significant for tailoring their structures and consequent properties and requires atomic precision in their preparation.Scanning probe microscopy(SPM),combined with on-surface synthesis strategy,has demonstrated its capabilities in fabrication of various carbon-based nanostructures and nanomaterials with atomic precision,which has long been elusive for conventional solution-phase synthesis due to realistic obstacles in solubility,isolation,purification,etc.More intriguingly,atom manipulation via an SPM tip allows unique access to local production of highly reactive carbon-based nanostructures.In addition,SPM provides topographic information of carbon-based nanostructures as well as their characteristic electronic structures with unprecedented submolecular resolution in real space.In this review,we overview recent exciting progress in the delicate application of SPM in probing low-dimensional carbon-based nanostructures and nanomaterials,which will open an avenue for the exploration and development of elusive and undiscovered carbon-based nanomaterials.展开更多
Scanning probe microscopes (SPM) are limited in their speed of data acquisition by the mechanical stability of the scanner. Therefore many types of scanners have been developed to achieve a rigid setup while maintaini...Scanning probe microscopes (SPM) are limited in their speed of data acquisition by the mechanical stability of the scanner. Therefore many types of scanners have been developed to achieve a rigid setup while maintaining an acceptable image size. We have followed here a different path to accelerate data acquisition by improving the feedback loop to achieve the same SPM image quality in a shorter time. While the feedback loop in a scanning probe microscope typically starts to probe a new pixel starting from the previous position, we have reduced the total control time by using an improved starting point for the feedback loop at each pixel. By exploiting the information of the already scanned pixels a forecast for the new pixel is created. We have successfully used several simple methods for a prognosis in MATLAB simulations like one dimensional linear or cubic extrapolation and others. Only scanning tunnelling microscope data from real experiments were used to test the forecasts. A doubling of the speed was achieved in the most favourable cases.展开更多
By employing scanning probe microscopy,conductive path and local oxygen-vacancy dynamics have been investigated in crosshatched La_(0.7)Sr_(0.3)MnO_(3) thin films grown onto flat and vicinal LaAlO_(3)(001)single cryst...By employing scanning probe microscopy,conductive path and local oxygen-vacancy dynamics have been investigated in crosshatched La_(0.7)Sr_(0.3)MnO_(3) thin films grown onto flat and vicinal LaAlO_(3)(001)single crystal substrates.Consistent with prior studies,the crosshatch topography was observed first by dynamical force microscopy as the epi-stain started to release with increasing film thickness.Second,by using conductive atomic force microscopy(CAFM),conductive crosshatch and dots(locally aligned or random)were unravelled,however,not all of which necessarily coincided with that shown in the in situ atomic force microscopy.Furthermore,the current-voltage responses were probed by CAFM,revealing the occurrence of threshold and/or memristive switchings.Our results demonstrate that the resistive switching relies on the evolution of the local profile and concentration of oxygen vacancies,which,in the crosshatched films,are modulated by both the misfit and threading dislocations.展开更多
A highly distorted chiral nanographene structure composed of triple corannulene-fused[5]helicenes is prepared with the help of the Heck reaction and oxidative photocyclization with an overall isolated yield of 28%.The...A highly distorted chiral nanographene structure composed of triple corannulene-fused[5]helicenes is prepared with the help of the Heck reaction and oxidative photocyclization with an overall isolated yield of 28%.The complex three-dimensional(3D)structure of the bowl-helix hybrid nanostructure is studied by a combination of noncontact atomic force microscopy(AFM)and scanning tunneling microscopy(STM)on the Cu(111)surface,density functional theory calculations,AFM/STM simulations,and high-performance liquid chromatography-electronic circular dichroism analysis.This examination reveals a molecular structure in which the three bowl-shaped corannulene bladesd position themselves in a C3-symmetric fashion around a highly twisted triphenylene core.The molecule appears to be shaped like a propeller in which the concave side of the bowls face away from the connected[5]helicene motif.The chirality of the nanostructure is confirmed by the direct visualization of both MMM and PPP enantiomers at the single-molecule level by scanning probe microscopies.These results underline that submolecular resolution imaging by AFM/STM is a powerful real-space tool for the stereochemical characterization of 3D curved chiral nanographene structures.展开更多
The rational design of efficient artificial photosynthetic components requires thorough understandings towards(photo)electrochemical properties and kinetic processes at the solid/liquid interface.Electrochemical scann...The rational design of efficient artificial photosynthetic components requires thorough understandings towards(photo)electrochemical properties and kinetic processes at the solid/liquid interface.Electrochemical scanning probe microscopy(EC-SPM),which enables the high-spatial resolution imaging in an electrolyte environment,becomes an indispensable experimental technique for operando studies of(photo)electrochemistry.This review summarizes the latest results of relevant ECSPM techniques to study the interfacial properties of electrocatalysts and photoelectrodes.Covered methods include atomic force microscopy,Kelvin probe force microscopy,conductive atomic force microscopy,scanning tunneling microscopy,scanning electrochemical microscopy,and other advanced SPM-based operando techniques.Finally,we offer some perspectives on the future outlook in this fascinating research area.展开更多
The corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate(SDS)was investigated by hydrogen analysis,scanning electron microscopy(SEM),electrochemical test,scanning Kelvin probe...The corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate(SDS)was investigated by hydrogen analysis,scanning electron microscopy(SEM),electrochemical test,scanning Kelvin probe force microscopy(SKPFM)and computational methods.Results showed that the corrosion resistance of Mg-8Li-3Al alloy in NaCl solution was effectively improved with SDS.The SEM and SKPFM results confirmed a dense,200 nm-thick SDS-adsorbed layer had formed on the alloy surface.The separation energy ΔE_(gap) and adsorption energy E_(ads) of SDS on the Mg surface were calculated by density functional theory and molecular dynamics simulations,respectively.And the corrosion inhibition mechanism was hypothesized and described.展开更多
Tip-enhanced Raman spectroscopy(TERS)imaging is a super-resolution imaging technique that features the merits of both surface-enhanced Raman spectroscopy(SERS)and scanning probe microscopy(SPM),such as the high chemic...Tip-enhanced Raman spectroscopy(TERS)imaging is a super-resolution imaging technique that features the merits of both surface-enhanced Raman spectroscopy(SERS)and scanning probe microscopy(SPM),such as the high chemical sensitivity from the former and the nanoscale spatial resolution from the latter.These advantages make TERS an essential nanospectroscopic characterization technique for chemical analysis,materials science,bio-sensing,etc.TERS probes,the most critical factor determining the TERS imaging quality,are expected to provide a highly confined electromagnetic hotspot with a minimized scattering background for the generation of Raman signals with high spatial resolution.After two decades of development,numerous probe design concepts have been proposed and demonstrated.This review provides a comprehensive overview of the state-of-the-art TERS probe designs,from the working mechanism to the practical performance.We start with reviewing the recent development of TERS configurations and the corresponding working mechanisms,including the SPM platforms,optical excitation/collection techniques,and probe preparation methods.We then review the emerging novel TERS probe designs,including the remote-excitation probes,the waveguide-based nanofocusing probes,the metal-coated nanofocusing probes,the nanowire-assisted selective-coupling probes,and the tapered metal-insulator-metal probes.Our discussion focuses on a few critical aspects,including the surface-plasmon-polariton(SPP)hotspot excitation technique,conversion efficiency,working frequency,and controllability.In the end,we review the latest TERS applications and give a perspective on the future of TERS.展开更多
Duplex stainless steels(DSSs)are suffering from various localized corrosion attacks such as pitting,selective dissolution,crevice corrosion during their service period.It is of great value to quantitatively analyze an...Duplex stainless steels(DSSs)are suffering from various localized corrosion attacks such as pitting,selective dissolution,crevice corrosion during their service period.It is of great value to quantitatively analyze and grasp the micro-electrochemical corrosion behavior and related mechanism for DSSs on the micrometer or even smaller scales.In this work,scanning Kelvin probe force microscopy(SKPFM)and energy dispersive spectroscopy(EDS)measurements were performed to reveal the difference between the austenite phase and ferrite phase in microregion of DSS 2205.Then traditional electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization(PDP)tests were employed for micro-electrochemical characterization of DSS 2205 with different proportion phases inϕ40 andϕ10μm micro holes.Both of them can only be utilized for qualitative or semi-quantitative micro-electrochemical characterization of DSS 2205.Coulostatic perturbation method was employed for quantitative micro-electrochemical characterization of DSS 2205.What is more,the applicable conditions of coulostatic perturbation were analyzed in depth by establishing a detailed electrochemical interface circuit.A series of microregion coulostatic perturbations for DSS 2205 with different proportion phases inϕ10μm micro holes showed that as the austenite proportion increases,the corresponding polarization resistance of microregion increases linearly.展开更多
The paper shows the results of the mathematical model development and the numerical simulation of the oxygen vacancies,and the distribution of TiO,Ti_(2)O_(3),and TiO_(2)oxides in the titanium oxide nanostructure obta...The paper shows the results of the mathematical model development and the numerical simulation of the oxygen vacancies,and the distribution of TiO,Ti_(2)O_(3),and TiO_(2)oxides in the titanium oxide nanostructure obtained by local anodic oxidation(anodization).The effect of the anodization voltage pulse duration and amplitude on the titanium oxide composition distribution and the conduction channel formation was shown.Synaptic device prototypes based on electrochemical titanium oxide are fabricated and investigated.It was shown that forming free resistive switching between the low resistances state(LRS)1.43±0.54 kΩand the high resistance state(HRS)28.75±9.75 kΩwere observed during 100,000 switching cycles and LRS 1.49±0.23 kΩwas maintained for 10,000 s.Multilevel resistive switching of the synaptic device prototype was investigated.It was shown that increasing Uset from 0.5 to 1.5 V leads to different LRS from 3.96±0.19 to 0.71±0.10 kΩ.The results obtained can be used in the development of technological foundations for the formation of high-performance multilevel artificial synapses for elements of neuroelectronics and hardware neural networks.展开更多
Artificial van der Waals(vdWs)heterostructures offer unprecedented opportunities to explore and reveal novel synergistic electronic and optical phenomena,which are beneficial for the development of novel optoelectroni...Artificial van der Waals(vdWs)heterostructures offer unprecedented opportunities to explore and reveal novel synergistic electronic and optical phenomena,which are beneficial for the development of novel optoelectronic devices at atomic limits.However,due to the damage caused by the device fabrication process,their inherent properties such as carrier mobility are obscured,which hinders the improvement of device performance and the incorporation of vdWs materials into next-generation integrated circuits.Herein,combining pump-probe spectroscopic and scanning probe microscopic techniques,the intrinsic optoelectronic properties of PtSe_(2)/MoSe_(2)heterojunction were nondestructively and systematically investigated.The heterojunction exhibits a broad-spectrum optical response and maintains ultrafast carrier dynamics(interfacial charge transfer~0.8 ps and carrier lifetime~38.2 ps)simultaneously.The in-plane exciton diffusion coefficient of the heterojunction was extracted(19.4±7.6 cm^(2)∙s^(−1)),and its exciton mobility as high as 756.8 cm^(2)∙V−1∙s^(−1)was deduced,exceeding the value of its components.This enhancement was attributed to the formation of an n-type Schottky junction between PtSe_(2)and MoSe_(2),and its built-in electric field assisted the ultrafast transfer of photogenerated carriers from MoSe_(2)to PtSe_(2),enhancing the in-plane exciton diffusion of the heterojunction.Our results demonstrate that PtSe_(2)/MoSe_(2)is suitable for the development of broadspectrum and sensitive optoelectronic devices.Meanwhile,the results contribute to a fundamental understanding of the performance of various optoelectronic devices based on such PtSe_(2)two-dimensional(2D)heterostructures.展开更多
Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of ...Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of polarization switching and electromechanical responses,making this technique advantageous over macroscopic approaches.Despite its widespread application in ferroelectrics,it has rarely been used to investigate the ferrielectric(FiE)behaviors in antiferroelectric(AFE)materials.Herein,the PFM was utilized to study the local electromechanical behavior and distribution of FiE,and the AFE phases of PbZrO_(3)thin-film were studied,where only the FiE behavior is observable using a macroscopic approach.The FiE region resembles a ferroelectric material at low voltages but exhibits a unique on-field amplitude response at high voltages.In contrast,the AFE region only yields an observable response at high voltages.Phase-field simulations reveal the coexistence of AFE and FiE states as well as the phase-transition processes that underpin our experimental observations.Our work illustrates the usefulness of PFM as an analytical tool to characterize AFE/FiE materials and their phase-coexistence behavior,thereby providing insights to guide property modification and potential applications.展开更多
The paper presents the results of an experimental study of the local polarization reversal and creation of domains by a biased tip of scanning probe microscope(SPM)in lithium niobate single crystals of congruent compo...The paper presents the results of an experimental study of the local polarization reversal and creation of domains by a biased tip of scanning probe microscope(SPM)in lithium niobate single crystals of congruent composition with a surface layer modified by soft proton exchange(SPE).The depth dependence of Ht ions concentration in the SPE-modified layer measured by confocal Raman microscopy demonstrates a sufficient composition gradient.The creation of isolated domains and stripe domain structures has been done by two switching modes:(1)point switching by field application in separated points and(2)line scanning switching by motion of the biased tip being in contact with the sample surface.For point switching for pulse durations less than 10 s,the logarithmic dependence of the domain diameter on the pulse duration was observed.The change of the dependence to a linear one for pulse duration above 10 s has been attributed to the transition from the stochastic step generation at the domain wall to the deterministic one at the domain vertexes.The periodical structure of stripe domains was created in SPE CLN planar waveguides by scanning at elevated temperature.The revealed switching regime suppresses electrostatic interaction of neighboring domains and leads to a significant improvement of the domain structure regularity.The creation of the stable periodical domain structure with submicron periods in SPE CLN planar waveguides was demonstrated.展开更多
Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-s...Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-surface chemistry involved in these areas is important for establishing composition-structure-performance relationships.With the rapid development of tip-enhanced Raman spectroscopy(TERS),it has become possible to investigate physical and chemical processes on suitable surfaces at the nanoscale level and in real space.In this review,after a brief introduction of the background of onsurface chemistry and TERS,we systematically discuss the progress in the application of TERS in this field.Our focus is the applications of TERS to nanoscale coordination processes,decomposition reactions,polymerization processes,electrochemical reactions,catalytic chemistry,and functionalization chemistry on solid surfaces.We conclude by discussing the future challenges and development of TERS techniques and related applications in on-surface chemistry.展开更多
The realization of long-range magnetic ordering in two-dimensional(2D)van der Waals systems significantly expands the scope of the 2D family as well as their possible spin-related phenomena and device applications.The...The realization of long-range magnetic ordering in two-dimensional(2D)van der Waals systems significantly expands the scope of the 2D family as well as their possible spin-related phenomena and device applications.The atomically thin nature of 2D materials makes their magnetically ordered states sensitive to local environments,and this necessitates advanced characterization at the atomic scale.Here,we briefly review several representative 2D magnetic systems,namely,iron chalcogenides,chromium chalcogenides,chromium trihalides,and their het-erostructures.With powerful scanning-probe microscopy,atomically resolved characterization of their crystalline configurations,electronic structures,and magnetization distributions has been achieved,and novel phenomena such as giant tunneling magnetoresistance and topological superconductivity have been observed.Finally,we discuss the challenges and new perspectives in this flourishing field.展开更多
Imaging biomolecules in real space is crucial for gaining a comprehensive understanding of the properties and functions of biological systems at the most fundamental level.Among the various imaging techniques availabl...Imaging biomolecules in real space is crucial for gaining a comprehensive understanding of the properties and functions of biological systems at the most fundamental level.Among the various imaging techniques available for biomolecules and their assembled nanostructures,scanning probe microscopy(SPM)provides a powerful and nondestructive imaging option.SPM is unique in visualizing intrinsically disordered biomolecules at the nanometer scale(e.g.,glycans).This review highlights recent achievements in studying biomolecules using SPM technique,focusing on DNA bases,amino acids,proteins,and glycans.The atomic-level analysis of biomolecules made possible by SPM allows for a more accurate definition of the local structure–property relationship.High-resolution SPM imaging of single biomolecules offers a new way to study basic processes of life at the molecular level.展开更多
To explore a proof-of-concept for atomically precise manufacturing(APM)using scanning probe microscopy(SPM),first principle theoretical calculations of atom-by-atom transfer from the apex of an SPM tip to an individua...To explore a proof-of-concept for atomically precise manufacturing(APM)using scanning probe microscopy(SPM),first principle theoretical calculations of atom-by-atom transfer from the apex of an SPM tip to an individual radical on a surfacebound organic molecule have been performed.Atom transfer is achieved by spatially controlled motion of a gold terminated tip to the radical.Two molecular tools for SPM-based APM have been designed and investigated,each comprising an adamantane core,a radical end group,and trithiol linkers to enable strong chemisorption on the Au(111)surface:ethynyl-adamantanetrithiol and adamantyl-trithiol.We demonstrate the details of controlled Au atom abstraction during tip approach toward and retraction from the radical species.Upon approach of the tip,the apical Au atom undergoes a transfer toward the carbon radical at a clearly defined threshold separation.This atomic displacement is accompanied by a net energy gain of the system in the range−0.5 to−1.5 eV,depending on the radical structure.In the case of a triangular pyramidal apex model,two tip configurations are possible after the tip atom displacement:(1)an Au atom is abstracted from the tip and bound to the C radical,not bound to the tip base anymore,and(2)apical tip atoms rearrange to form a continuous neck between the tip and radical.In the second case,subsequent tip retraction leads to the same final configuration as the first,with the abstracted Au atom bound to radical carbon atom of the molecular tool.For the less reactive adamantyl-trithiol radical molecular tool,Au atom transfer is less energetically favored,but this has the advantage of avoiding other apex gold atoms from rearrangement.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51922056 and 51921005).
文摘Ferroelectric polymer nanocomposites possess exceptional electric properties with respect to the two otherwise uniform phases,which is commonly attributed to the critical role of the matrix-particle interfacial region.However,the structure-property correlation of the interface remains unestablished,and thus,the design of ferroelectric polymer nanocompos-ite has largely relied on the trial-and-error method.Here,a strategy that combines multi-mode scanning probe microscopy-based electrical charac-terization and nano-infrared spectroscopy is developed to unveil the local structure-property correlation of the interface in ferroelectric polymer nano-composites.The results show that the type of surface modifiers decorated on the nanoparticles can significantly influence the local polar-phase content and the piezoelectric effect of the polymer matrix surrounding the nano-particles.The strongly coupled polar-phase content and piezoelectric effect measured directly in the interfacial region as well as the computed bonding energy suggest that the property enhancement originates from the formation of hydrogen bond between the surface modifiers and the ferroelectric polymer.It is also directly detected that the local domain size of the ferroelectric polymer can impact the energy level and distribution of charge traps in the interfacial region and eventually influence the local dielectric strength.
文摘The microscopic physical properties of Hardened Cement Paste (HCP) surfaces were evaluated by using Scanning Probe Microscopy (SPM). The cement pastes were cured under a hydrostatic pressure of 400 MPa and the contacting surfaces with a slide glass during the curing were studied. Scanning Electron Microscope (SEM) observation at a magnification of 7000 revealed smooth surfaces with no holes. The surface roughness calculated from the SPM measurement was 4 nm. The surface potential and the frictional force measured by SPM were uniform throughout the measured area 24 h after the curing. However, spots of low surface potential and stains of low frictional force and low viscoelasticity were observed one month after curing. This change was attributed to the carbonation of hydrates.
文摘In this work,we investigate cross-sectional sample preparation for atomic force microscopy and general scanning probe microscopy(SPM)characterization.In light of traditional cross-sectional sample preparation solutions for transmission electron microscopy,mechanical polishing and focused ion beam(FIB)milling have been employed to prepare cross-sectional samples for SPM.We present an optimized solution for thin films and oxide heterostructures that allows for examining the prepared surfaces using various SPM techniques.In particular,post-cleaning after FIB milling is shown to be crucial and precision ion polishing was conducted to remove rough layers on mechanically polished samples.We also study SPM mechanical milling to remove amorphous layers on FIB-milled samples.Consequently,a reliable solution for making cross sections suitable for SPM has been achieved providing a useful methodology that can also be employed for other material systems with different hardness,such as polymers and metals.
基金financial support from the National Natural Science Foundation of China(Grant Nos.22125203,21790351)the Fundamental Research Funds for the Central Universities(Grant No.22120220051).
文摘Carbon,as an indispensable chemical element on Earth,has diverse covalent bonding ability,which enables construction of extensive pivotal carbon-based structures in multiple scientific fields.The extraordinary physicochemical properties presented by pioneering synthetic carbon allotropes,typically including fullerenes,carbon nanotubes,and graphene,have stimulated broad interest in fabrication of carbon-based nanostructures and nanomaterials.Accurate regulation of topology,size,and shape,as well as controllably embedding target sp^(n)-hybridized carbons in molecular skeletons,is significant for tailoring their structures and consequent properties and requires atomic precision in their preparation.Scanning probe microscopy(SPM),combined with on-surface synthesis strategy,has demonstrated its capabilities in fabrication of various carbon-based nanostructures and nanomaterials with atomic precision,which has long been elusive for conventional solution-phase synthesis due to realistic obstacles in solubility,isolation,purification,etc.More intriguingly,atom manipulation via an SPM tip allows unique access to local production of highly reactive carbon-based nanostructures.In addition,SPM provides topographic information of carbon-based nanostructures as well as their characteristic electronic structures with unprecedented submolecular resolution in real space.In this review,we overview recent exciting progress in the delicate application of SPM in probing low-dimensional carbon-based nanostructures and nanomaterials,which will open an avenue for the exploration and development of elusive and undiscovered carbon-based nanomaterials.
文摘Scanning probe microscopes (SPM) are limited in their speed of data acquisition by the mechanical stability of the scanner. Therefore many types of scanners have been developed to achieve a rigid setup while maintaining an acceptable image size. We have followed here a different path to accelerate data acquisition by improving the feedback loop to achieve the same SPM image quality in a shorter time. While the feedback loop in a scanning probe microscope typically starts to probe a new pixel starting from the previous position, we have reduced the total control time by using an improved starting point for the feedback loop at each pixel. By exploiting the information of the already scanned pixels a forecast for the new pixel is created. We have successfully used several simple methods for a prognosis in MATLAB simulations like one dimensional linear or cubic extrapolation and others. Only scanning tunnelling microscope data from real experiments were used to test the forecasts. A doubling of the speed was achieved in the most favourable cases.
基金funded by the Science Center of the National Science Foundation of China(Grant No.52088101)the National Natural Science Foundation of China(Grant Nos.11474342 and11174353)+2 种基金the National Key Research and Development Program of Chinathe Strategic Priority Research Program B of the Chinese Academy of Sciencessupported in part by the beamline 08U1A of SSRF。
文摘By employing scanning probe microscopy,conductive path and local oxygen-vacancy dynamics have been investigated in crosshatched La_(0.7)Sr_(0.3)MnO_(3) thin films grown onto flat and vicinal LaAlO_(3)(001)single crystal substrates.Consistent with prior studies,the crosshatch topography was observed first by dynamical force microscopy as the epi-stain started to release with increasing film thickness.Second,by using conductive atomic force microscopy(CAFM),conductive crosshatch and dots(locally aligned or random)were unravelled,however,not all of which necessarily coincided with that shown in the in situ atomic force microscopy.Furthermore,the current-voltage responses were probed by CAFM,revealing the occurrence of threshold and/or memristive switchings.Our results demonstrate that the resistive switching relies on the evolution of the local profile and concentration of oxygen vacancies,which,in the crosshatched films,are modulated by both the misfit and threading dislocations.
基金Financial support from the Ministry of Education Singapore under the AcRF Tier 1(MOE T1 RG11/21)and AcRF Tier 2(MOE-T2EP10221-0002)The Deutsche Forschungsgemeinschaft via grants(nos.SCHI 619/13 and EB535/1-1)+5 种基金the GRK(Research Training Group)2204“Substitute Materials for Sustainable Energy Technologies”the LOEWE Program of Excellence of the Federal State of Hesse(LOEWE Focus Group PriOSS“Principles of On-Surface Synthesis”)the National Natural Science Foundation of China(grant nos.21790053,51821002,and 22072103)the National Major State Basic Research Development Program of China(grant nos.2017YFA0205000 and 2017YFA0205002)the Collaborative Innovation Center of Suzhou Nano Science&Technologythe 111 Project are also acknowledged for their financial support.
文摘A highly distorted chiral nanographene structure composed of triple corannulene-fused[5]helicenes is prepared with the help of the Heck reaction and oxidative photocyclization with an overall isolated yield of 28%.The complex three-dimensional(3D)structure of the bowl-helix hybrid nanostructure is studied by a combination of noncontact atomic force microscopy(AFM)and scanning tunneling microscopy(STM)on the Cu(111)surface,density functional theory calculations,AFM/STM simulations,and high-performance liquid chromatography-electronic circular dichroism analysis.This examination reveals a molecular structure in which the three bowl-shaped corannulene bladesd position themselves in a C3-symmetric fashion around a highly twisted triphenylene core.The molecule appears to be shaped like a propeller in which the concave side of the bowls face away from the connected[5]helicene motif.The chirality of the nanostructure is confirmed by the direct visualization of both MMM and PPP enantiomers at the single-molecule level by scanning probe microscopies.These results underline that submolecular resolution imaging by AFM/STM is a powerful real-space tool for the stereochemical characterization of 3D curved chiral nanographene structures.
基金funded by the National Natural Science Foundation of China(Nos.21872039 and 22072030)the Fundamental Research Funds for the Central Universities(No.20720220008)the Science and Technology Commission of Shanghai Municipality(No.22520711100).
文摘The rational design of efficient artificial photosynthetic components requires thorough understandings towards(photo)electrochemical properties and kinetic processes at the solid/liquid interface.Electrochemical scanning probe microscopy(EC-SPM),which enables the high-spatial resolution imaging in an electrolyte environment,becomes an indispensable experimental technique for operando studies of(photo)electrochemistry.This review summarizes the latest results of relevant ECSPM techniques to study the interfacial properties of electrocatalysts and photoelectrodes.Covered methods include atomic force microscopy,Kelvin probe force microscopy,conductive atomic force microscopy,scanning tunneling microscopy,scanning electrochemical microscopy,and other advanced SPM-based operando techniques.Finally,we offer some perspectives on the future outlook in this fascinating research area.
基金the financial support by the National Natural Science Foundation of China(51961026)the Interdisciplinary Innovation Fund of Nanchang University(Project No.2019-9166-27060003)。
文摘The corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate(SDS)was investigated by hydrogen analysis,scanning electron microscopy(SEM),electrochemical test,scanning Kelvin probe force microscopy(SKPFM)and computational methods.Results showed that the corrosion resistance of Mg-8Li-3Al alloy in NaCl solution was effectively improved with SDS.The SEM and SKPFM results confirmed a dense,200 nm-thick SDS-adsorbed layer had formed on the alloy surface.The separation energy ΔE_(gap) and adsorption energy E_(ads) of SDS on the Mg surface were calculated by density functional theory and molecular dynamics simulations,respectively.And the corrosion inhibition mechanism was hypothesized and described.
基金supported by the National Science Foundation(Nos.1654746 and 1810453).
文摘Tip-enhanced Raman spectroscopy(TERS)imaging is a super-resolution imaging technique that features the merits of both surface-enhanced Raman spectroscopy(SERS)and scanning probe microscopy(SPM),such as the high chemical sensitivity from the former and the nanoscale spatial resolution from the latter.These advantages make TERS an essential nanospectroscopic characterization technique for chemical analysis,materials science,bio-sensing,etc.TERS probes,the most critical factor determining the TERS imaging quality,are expected to provide a highly confined electromagnetic hotspot with a minimized scattering background for the generation of Raman signals with high spatial resolution.After two decades of development,numerous probe design concepts have been proposed and demonstrated.This review provides a comprehensive overview of the state-of-the-art TERS probe designs,from the working mechanism to the practical performance.We start with reviewing the recent development of TERS configurations and the corresponding working mechanisms,including the SPM platforms,optical excitation/collection techniques,and probe preparation methods.We then review the emerging novel TERS probe designs,including the remote-excitation probes,the waveguide-based nanofocusing probes,the metal-coated nanofocusing probes,the nanowire-assisted selective-coupling probes,and the tapered metal-insulator-metal probes.Our discussion focuses on a few critical aspects,including the surface-plasmon-polariton(SPP)hotspot excitation technique,conversion efficiency,working frequency,and controllability.In the end,we review the latest TERS applications and give a perspective on the future of TERS.
基金financial support from the Ministry of Science and Technology, China for the national key research and development plan (No. 2017YFB0701904)China Nuclear Power Engineering Co., Ltd. (No. KY1672)the 111 Project (No. B12012)
文摘Duplex stainless steels(DSSs)are suffering from various localized corrosion attacks such as pitting,selective dissolution,crevice corrosion during their service period.It is of great value to quantitatively analyze and grasp the micro-electrochemical corrosion behavior and related mechanism for DSSs on the micrometer or even smaller scales.In this work,scanning Kelvin probe force microscopy(SKPFM)and energy dispersive spectroscopy(EDS)measurements were performed to reveal the difference between the austenite phase and ferrite phase in microregion of DSS 2205.Then traditional electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization(PDP)tests were employed for micro-electrochemical characterization of DSS 2205 with different proportion phases inϕ40 andϕ10μm micro holes.Both of them can only be utilized for qualitative or semi-quantitative micro-electrochemical characterization of DSS 2205.Coulostatic perturbation method was employed for quantitative micro-electrochemical characterization of DSS 2205.What is more,the applicable conditions of coulostatic perturbation were analyzed in depth by establishing a detailed electrochemical interface circuit.A series of microregion coulostatic perturbations for DSS 2205 with different proportion phases inϕ10μm micro holes showed that as the austenite proportion increases,the corresponding polarization resistance of microregion increases linearly.
基金The reported study was funded by the Russian Federation Government(Agreement No.075-15-2022-1123)(mathematical model development and theoretical calculations)The fabrication of memristor structures and their resistive switching investigation were supported by a grant from the Russian Science Foundation No.22-79-10215,https://rscf.ru/project/22-79-10215/,at Southern Federal University.Multilevel switching was researched with the financial support of the grant of the President of the Russian FederationМК-2290.2022.4。
文摘The paper shows the results of the mathematical model development and the numerical simulation of the oxygen vacancies,and the distribution of TiO,Ti_(2)O_(3),and TiO_(2)oxides in the titanium oxide nanostructure obtained by local anodic oxidation(anodization).The effect of the anodization voltage pulse duration and amplitude on the titanium oxide composition distribution and the conduction channel formation was shown.Synaptic device prototypes based on electrochemical titanium oxide are fabricated and investigated.It was shown that forming free resistive switching between the low resistances state(LRS)1.43±0.54 kΩand the high resistance state(HRS)28.75±9.75 kΩwere observed during 100,000 switching cycles and LRS 1.49±0.23 kΩwas maintained for 10,000 s.Multilevel resistive switching of the synaptic device prototype was investigated.It was shown that increasing Uset from 0.5 to 1.5 V leads to different LRS from 3.96±0.19 to 0.71±0.10 kΩ.The results obtained can be used in the development of technological foundations for the formation of high-performance multilevel artificial synapses for elements of neuroelectronics and hardware neural networks.
基金supported by the National Natural Science Foundation of China(Nos.11974088,61975007,52172060,61925401,92064004,61927901,and 92164302)the Beijing Natural Science Foundation(Nos.Z190006 and 4222073)+1 种基金the National Key R&D Program of China(No.2018YFA0208402),the 111 Project(No.B18001)the Fok Ying-Tong Education Foundation,and the Tencent Foundation through the XPLORER PRIZE。
文摘Artificial van der Waals(vdWs)heterostructures offer unprecedented opportunities to explore and reveal novel synergistic electronic and optical phenomena,which are beneficial for the development of novel optoelectronic devices at atomic limits.However,due to the damage caused by the device fabrication process,their inherent properties such as carrier mobility are obscured,which hinders the improvement of device performance and the incorporation of vdWs materials into next-generation integrated circuits.Herein,combining pump-probe spectroscopic and scanning probe microscopic techniques,the intrinsic optoelectronic properties of PtSe_(2)/MoSe_(2)heterojunction were nondestructively and systematically investigated.The heterojunction exhibits a broad-spectrum optical response and maintains ultrafast carrier dynamics(interfacial charge transfer~0.8 ps and carrier lifetime~38.2 ps)simultaneously.The in-plane exciton diffusion coefficient of the heterojunction was extracted(19.4±7.6 cm^(2)∙s^(−1)),and its exciton mobility as high as 756.8 cm^(2)∙V−1∙s^(−1)was deduced,exceeding the value of its components.This enhancement was attributed to the formation of an n-type Schottky junction between PtSe_(2)and MoSe_(2),and its built-in electric field assisted the ultrafast transfer of photogenerated carriers from MoSe_(2)to PtSe_(2),enhancing the in-plane exciton diffusion of the heterojunction.Our results demonstrate that PtSe_(2)/MoSe_(2)is suitable for the development of broadspectrum and sensitive optoelectronic devices.Meanwhile,the results contribute to a fundamental understanding of the performance of various optoelectronic devices based on such PtSe_(2)two-dimensional(2D)heterostructures.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(No.2019R1I1A1A01063888)the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2019R1A6A1A03033215)F.P.Z.acknowledges the Alexander von Humboldt Foundation(AvH)for the fellowship with award number 1203828,and Z.L.acknowledges the LOEWE program of the State of Hesse,Germany,within the project FLAME(Fermi Level Engineering of Antiferroelectric Materials for Energy Storage and Insulation Systems).
文摘Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of polarization switching and electromechanical responses,making this technique advantageous over macroscopic approaches.Despite its widespread application in ferroelectrics,it has rarely been used to investigate the ferrielectric(FiE)behaviors in antiferroelectric(AFE)materials.Herein,the PFM was utilized to study the local electromechanical behavior and distribution of FiE,and the AFE phases of PbZrO_(3)thin-film were studied,where only the FiE behavior is observable using a macroscopic approach.The FiE region resembles a ferroelectric material at low voltages but exhibits a unique on-field amplitude response at high voltages.In contrast,the AFE region only yields an observable response at high voltages.Phase-field simulations reveal the coexistence of AFE and FiE states as well as the phase-transition processes that underpin our experimental observations.Our work illustrates the usefulness of PFM as an analytical tool to characterize AFE/FiE materials and their phase-coexistence behavior,thereby providing insights to guide property modification and potential applications.
基金supported by the Ministry of Science and Higher Education of the Russian Federation within the Development Program of the Ural Federal University named after the first President of Russia,B.N.Yeltsin,in accordance with the program of strategic academic leadership“Priority-2030”.The equipment of the Ural Center for Shared Use“Modern nanotechnology”at Ural Federal University(Reg.No.2968),which is supported by the Ministry of Science and Higher Education RF(Project No.075-15-2021-677),was used.
文摘The paper presents the results of an experimental study of the local polarization reversal and creation of domains by a biased tip of scanning probe microscope(SPM)in lithium niobate single crystals of congruent composition with a surface layer modified by soft proton exchange(SPE).The depth dependence of Ht ions concentration in the SPE-modified layer measured by confocal Raman microscopy demonstrates a sufficient composition gradient.The creation of isolated domains and stripe domain structures has been done by two switching modes:(1)point switching by field application in separated points and(2)line scanning switching by motion of the biased tip being in contact with the sample surface.For point switching for pulse durations less than 10 s,the logarithmic dependence of the domain diameter on the pulse duration was observed.The change of the dependence to a linear one for pulse duration above 10 s has been attributed to the transition from the stochastic step generation at the domain wall to the deterministic one at the domain vertexes.The periodical structure of stripe domains was created in SPE CLN planar waveguides by scanning at elevated temperature.The revealed switching regime suppresses electrostatic interaction of neighboring domains and leads to a significant improvement of the domain structure regularity.The creation of the stable periodical domain structure with submicron periods in SPE CLN planar waveguides was demonstrated.
基金We acknowledge financial support from the ERC program(Grant No.741431-2DNanoSpec).
文摘Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-surface chemistry involved in these areas is important for establishing composition-structure-performance relationships.With the rapid development of tip-enhanced Raman spectroscopy(TERS),it has become possible to investigate physical and chemical processes on suitable surfaces at the nanoscale level and in real space.In this review,after a brief introduction of the background of onsurface chemistry and TERS,we systematically discuss the progress in the application of TERS in this field.Our focus is the applications of TERS to nanoscale coordination processes,decomposition reactions,polymerization processes,electrochemical reactions,catalytic chemistry,and functionalization chemistry on solid surfaces.We conclude by discussing the future challenges and development of TERS techniques and related applications in on-surface chemistry.
基金The authors acknowledge financial support from the National Nat-ural Science Foundation of China(Grant No.12004278)the Natural Science Foundation of Fujian Province(2022J06035)the Ministry of Education,Singapore,under its ARC Tier 2 program(Award T2EP-50122-0007).
文摘The realization of long-range magnetic ordering in two-dimensional(2D)van der Waals systems significantly expands the scope of the 2D family as well as their possible spin-related phenomena and device applications.The atomically thin nature of 2D materials makes their magnetically ordered states sensitive to local environments,and this necessitates advanced characterization at the atomic scale.Here,we briefly review several representative 2D magnetic systems,namely,iron chalcogenides,chromium chalcogenides,chromium trihalides,and their het-erostructures.With powerful scanning-probe microscopy,atomically resolved characterization of their crystalline configurations,electronic structures,and magnetization distributions has been achieved,and novel phenomena such as giant tunneling magnetoresistance and topological superconductivity have been observed.Finally,we discuss the challenges and new perspectives in this flourishing field.
基金support of the Beijing Natural Science Foundation(Nos.Z190006 and 4192054)National Key Research and Development Program of China(Nos.2019YFA0308000,2020YFA0308800,and 2021YFA1400100)+1 种基金National Natural Science Foundation of China(Nos.92163206,61971035,61725107,and 62271048)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB30000000).
文摘Imaging biomolecules in real space is crucial for gaining a comprehensive understanding of the properties and functions of biological systems at the most fundamental level.Among the various imaging techniques available for biomolecules and their assembled nanostructures,scanning probe microscopy(SPM)provides a powerful and nondestructive imaging option.SPM is unique in visualizing intrinsically disordered biomolecules at the nanometer scale(e.g.,glycans).This review highlights recent achievements in studying biomolecules using SPM technique,focusing on DNA bases,amino acids,proteins,and glycans.The atomic-level analysis of biomolecules made possible by SPM allows for a more accurate definition of the local structure–property relationship.High-resolution SPM imaging of single biomolecules offers a new way to study basic processes of life at the molecular level.
基金funded by the US Department of Energy,Office of Energy Efficiency and Renewable Energy under Award Number DE-EE0008308funded by the Extreme Science and Engineering Discovery Environment(XSEDE)which is supported by National Science Foundation Grant Number TG-CHE170060.25 Specifically,it used the Bridges,Bridges-2(Pittsburgh Supercomputing Center(PSC)),and SDSC Expanse compute systems.
文摘To explore a proof-of-concept for atomically precise manufacturing(APM)using scanning probe microscopy(SPM),first principle theoretical calculations of atom-by-atom transfer from the apex of an SPM tip to an individual radical on a surfacebound organic molecule have been performed.Atom transfer is achieved by spatially controlled motion of a gold terminated tip to the radical.Two molecular tools for SPM-based APM have been designed and investigated,each comprising an adamantane core,a radical end group,and trithiol linkers to enable strong chemisorption on the Au(111)surface:ethynyl-adamantanetrithiol and adamantyl-trithiol.We demonstrate the details of controlled Au atom abstraction during tip approach toward and retraction from the radical species.Upon approach of the tip,the apical Au atom undergoes a transfer toward the carbon radical at a clearly defined threshold separation.This atomic displacement is accompanied by a net energy gain of the system in the range−0.5 to−1.5 eV,depending on the radical structure.In the case of a triangular pyramidal apex model,two tip configurations are possible after the tip atom displacement:(1)an Au atom is abstracted from the tip and bound to the C radical,not bound to the tip base anymore,and(2)apical tip atoms rearrange to form a continuous neck between the tip and radical.In the second case,subsequent tip retraction leads to the same final configuration as the first,with the abstracted Au atom bound to radical carbon atom of the molecular tool.For the less reactive adamantyl-trithiol radical molecular tool,Au atom transfer is less energetically favored,but this has the advantage of avoiding other apex gold atoms from rearrangement.
基金financially supported by the National Natural Science Foundation of China(NSFC,U21A20500,52072115,51972102)the Natural Science Project of Hubei Province in China(2023AFB758,2022CFB518)。