As a novel class of high-voltage cathode materials,spinel lithium transition metal oxides have been faced with demerits including pronounced structural instability caused by Jahn-Teller distortion(especially at the lo...As a novel class of high-voltage cathode materials,spinel lithium transition metal oxides have been faced with demerits including pronounced structural instability caused by Jahn-Teller distortion(especially at the lower voltage region)and severe capacity degradation despite their intriguing electrochemical properties.To extend their functionalities as broad-voltage cathodes,the sacrificial template method has been regarded as a promising way to realize structural and compositional control for desirable electrochemical behaviors.Herein,we report a synthetic protocol to directionally prepare Li Co Mn O_(4)(LCMO)using carboxyl-based metal-organic frameworks(MOFs)as self-sacrificing templates.Impressively,LCMO derived from Co Mn-BDC(H_(2)BDC=1,4-benzenedicarboxylate)displays superior electrochemical performances with a specific capacity of 151.6 m Ah g^(-1)at 1 C(150 m A g^(-1))after 120 cycles and excellent rate capacity of 91.9 m Ah g^(-1)at 10 C due to the morphology control,microstructural modulation,and atomic manipulation of the MOF precursor.Bestowed by the optimized atomic and electronic structure,abundant oxygen vacancies,and the nanostructure retained from MOF precursors,LCMO materials display extraordinary electrochemical properties,which have been extensively verified by both experimental and theoretical studies.This work not only provides guidelines for the directional design of spinel materials at molecular and atomic levels but also sheds light on the practical use of LIBs with broad range voltage.展开更多
We propose a novel on-chip platform for controlling and manipulating cold atoms precisely and coherently. The scheme is achieved by producing optically induced fictitious magnetic traps（OFMTs） with 790 nm（for -（87...We propose a novel on-chip platform for controlling and manipulating cold atoms precisely and coherently. The scheme is achieved by producing optically induced fictitious magnetic traps（OFMTs） with 790 nm（for -（87）Rb） circularly polarized laser beams and state-dependent potentials simultaneously for two internal atomic states with microwave coplanar waveguides. We carry out numerical calculations and simulations for controlled collisional interactions between OFMTs and addressable single atoms＇ manipulation on our designed hybrid atom chips. The results show that our proposed platform is feasible and flexible, which has wide applications including collisional dynamics investigation, entanglement generation,and scalable quantum gates implementation.展开更多
Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the meth...Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the methods in defect controlcurrently face challenges with overly large operational areas and a lack of precision in targeting specific defects. Therefore,we propose a new method for the precise and universal defect healing of TMD materials, integrating real-time imaging withscanning transmission electron microscopy (STEM). This method employs electron beam irradiation to stimulate the diffusionmigration of surface-adsorbed adatoms on TMD materials grown by low-temperature molecular beam epitaxy (MBE),and heal defects within the diffusion range. This approach covers defect repairs ranging from zero-dimensional vacancydefects to two-dimensional grain orientation alignment, demonstrating its universality in terms of the types of samples anddefects. These findings offer insights into the use of atomic-level focused electron beams at appropriate voltages in STEMfor defect healing, providing valuable experience for achieving atomic-level precise fabrication of TMD materials.展开更多
The Lande g-factor of a free atom determines the effective magnetic moment of an electron or atom with both spin and orbital angular momentum,which can be calculated by Lande formula,for a transition metal ion in the ...The Lande g-factor of a free atom determines the effective magnetic moment of an electron or atom with both spin and orbital angular momentum,which can be calculated by Lande formula,for a transition metal ion in the crystal field,the spin-orbital interaction can mix the non-zero orbital angular momentum of excited states with the＂pure spin＂ground state,resulting in an effective g-factor.Thus,the ability to probe the fine structure of the g-factor allows us to understand the internal spin properties of a magnetic system,such as the spin-orbital interaction.However,for molecular systems,traditional experimental methods for g-factor measurement,like EPR.展开更多
The manipulation of single atom within the metallic kernel of nanoclusters has attracted considerable attention due to its potentials to elucidate kernel-based structure-property relationships at the single-atom level...The manipulation of single atom within the metallic kernel of nanoclusters has attracted considerable attention due to its potentials to elucidate kernel-based structure-property relationships at the single-atom level.Herein,new-designed chiral bialkynyl ligands,have been chosen as protective agents to isolate two pairs of 8-electron superatomic silver nanoclusters,R/S-Ag39 and R/S-Ag40.X-ray diffraction analysis reveals that Ag39 and Ag40 with the same number of chiral ligands,possess a closely analogous silver skeleton but a single-atomic difference.The incorporation of an extra Ag40th atom into Ag40 evokes two significant changes of structure and property compared to Ag39:(i)a reduction in the symmetry of the entire nanocluster,resulting in an enhancement of kernel-related asymmetry g-factor;(ii)a regulation of the transitions(1P→1D and Ligand(π)→1D)of excited state,leading to a second near-infrared(NIR-II,1000-1700 nm)phosphorescent emission red-shift from 1088 to 1150 nm.This work not only provides vital insights into the relationship between structures and ground/excited states chiroptical activities at the single-atom level,but also presents bialkynyl as a promising stabilizing agent for building superatomic metal nanoclusters.展开更多
In the fabrication process of nanoelectronic device arrays based on single-wall carbon nanotube(SWCNT),oriented alignment of SWCNTs and property modification of metallic SWCNTs in the array are the key problems to be ...In the fabrication process of nanoelectronic device arrays based on single-wall carbon nanotube(SWCNT),oriented alignment of SWCNTs and property modification of metallic SWCNTs in the array are the key problems to be solved.Pulse gas alignment with substrate downward tilt is proposed to realize the controllable alignment of SWCNTs.Experimental results demonstrate that 84%SWCNTs are aligned in-15°―15°angular to the pulse gas direction.A modified nanomanipulation technology based on atomic force microscope(AFM)is utilized to perform various kinds of SWCNT manipulation,such as SWCNT separation from the"Y"CNT,catalyst removal from the SWCNT end,continual nano buckles fabrication on SWCNT and even stretching to break,which provides a feasible way to modify the size,shape and the electrical property of SWCNTs.展开更多
The capability to image, as well as control and manipulate single molecules such as nucleic acids(DNA or RNA) can greatly enrich our knowledge of the roles of individual biomolecules in cellular processes and their be...The capability to image, as well as control and manipulate single molecules such as nucleic acids(DNA or RNA) can greatly enrich our knowledge of the roles of individual biomolecules in cellular processes and their behavior in native environments. Here we summarize the recent advances of single nucleic acid imaging based on optical observation and force manipulation. We start by discussing the superiority of single molecule image, the central roles nucleic acids play in biosystems, and the significance of single molecule image towards nucleic acids. We then list a series of representative examples in brief to illustrate how nucleic acid of various morphologies has been imaged from different aspects, and what can be learned from such characterizations. Finally,concluding remarks on parts of which should be improved and outlook are outlined.展开更多
Writing at the nanoscale using the desorption of oxygen adatoms from the oxygen-rich MoO2＋x/Mo（110） surface is demonstrated by scanning tunnelling microscopy （STM）. High-temperature oxidation of the Mo（110） sur...Writing at the nanoscale using the desorption of oxygen adatoms from the oxygen-rich MoO2＋x/Mo（110） surface is demonstrated by scanning tunnelling microscopy （STM）. High-temperature oxidation of the Mo（110） surface results in a strained, bulk-like MOO2（010） ultra-thin film with an O-Mo-O trilayer structure. Due to the lattice mismatch between the Mo（110） and the MOO2（010）, the latter consists of well-ordered molybdenum oxide nanorows separated by 2.5 nm. The MoO2（010）/Mo（110） structure is confirmed by STM data and density functional theory calculations. Further oxidation results in the oxygen-rich MoOa^x/Mo（110） surface, which exhibits perfectly aligned double rows of oxygen adatoms, imaged by STM as bright protrusions. These adatoms can be removed from the surface by scanning （or pulsing） at positive sample biases greater than 1.5 V. Tip movement along the surface can be used for controlled lithography （or writing） at the nanoscale, with a minimum feature size of just 3 nm. By moving the STM tip in a predetermined fashion, information can be written and read by applying specific biases between the surface and the tip.展开更多
Topological defects in graphene materials introduce exotic properties with both fundamental importance and technological implications,absent in their defect-free counterparts.Although individual topological defects ha...Topological defects in graphene materials introduce exotic properties with both fundamental importance and technological implications,absent in their defect-free counterparts.Although individual topological defects have been widely studied,collective magnetic behaviors originating from well-organized multiple topological defects remain a great challenge.Here,we examined the collective magnetic properties originating from three pentagon topological defects in truxene-based molecular graphenoids using scanning tunneling microscopy(STM)and non-contact atomic force microscopy.Unpairedπelectrons were introduced into the aromatic topology of truxene molecular graphenoids one by one by dissociating hydrogen atoms at the pentagon defects via atom manipulation.STM measurements,together with density functional theory calculations,suggested that the unpaired electrons were ferromagnetically coupled,forming a collective highspin quartet state of S=3/2.Our work demonstrates that collective spin ordering could be realized through engineering regular patterned topological defects in molecular graphenoids,providing a new platform for designing one-dimensional ferromagnetic spin chains and two-dimensional ferromagnetic networks.展开更多
基金the financial support from the Special Funds for the Cultivation of Guangdong College Students’Scientific and Technological Innovation(“Climbing Program”Special Funds,pdjh2022b0135)the Open Fund of Energy and Materials Chemistry Joint Laboratory of SCNU and TINCI(SCNU-TINCI202207)。
文摘As a novel class of high-voltage cathode materials,spinel lithium transition metal oxides have been faced with demerits including pronounced structural instability caused by Jahn-Teller distortion(especially at the lower voltage region)and severe capacity degradation despite their intriguing electrochemical properties.To extend their functionalities as broad-voltage cathodes,the sacrificial template method has been regarded as a promising way to realize structural and compositional control for desirable electrochemical behaviors.Herein,we report a synthetic protocol to directionally prepare Li Co Mn O_(4)(LCMO)using carboxyl-based metal-organic frameworks(MOFs)as self-sacrificing templates.Impressively,LCMO derived from Co Mn-BDC(H_(2)BDC=1,4-benzenedicarboxylate)displays superior electrochemical performances with a specific capacity of 151.6 m Ah g^(-1)at 1 C(150 m A g^(-1))after 120 cycles and excellent rate capacity of 91.9 m Ah g^(-1)at 10 C due to the morphology control,microstructural modulation,and atomic manipulation of the MOF precursor.Bestowed by the optimized atomic and electronic structure,abundant oxygen vacancies,and the nanostructure retained from MOF precursors,LCMO materials display extraordinary electrochemical properties,which have been extensively verified by both experimental and theoretical studies.This work not only provides guidelines for the directional design of spinel materials at molecular and atomic levels but also sheds light on the practical use of LIBs with broad range voltage.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0302800)the National Natural Science Foundation of China(Grant No.11674361)
文摘We propose a novel on-chip platform for controlling and manipulating cold atoms precisely and coherently. The scheme is achieved by producing optically induced fictitious magnetic traps（OFMTs） with 790 nm（for -（87）Rb） circularly polarized laser beams and state-dependent potentials simultaneously for two internal atomic states with microwave coplanar waveguides. We carry out numerical calculations and simulations for controlled collisional interactions between OFMTs and addressable single atoms＇ manipulation on our designed hybrid atom chips. The results show that our proposed platform is feasible and flexible, which has wide applications including collisional dynamics investigation, entanglement generation,and scalable quantum gates implementation.
基金the Beijing Natural Science Foundation(Grant Nos.JQ24010 and Z220020)the Fundamental Research Funds for the Central Universities,and the National Natural Science Foundation of China(Grant No.52273279)Project supported by the Electron Microscopy Laboratory of Peking University,China for the use of Nion U-HERMES200 scanning transmission electron microscopy.We thank Materials Processing and Analysis Center,Peking University,for assistance with TEM characterization.The electron microscopy work was through a user project at Center of Oak Ridge National Laboratory(ORNL)for Nanophase Materials Sciences(CNMS),which is a DOE Office of Science User Facility.
文摘Minimizing disorder and defects is crucial for realizing the full potential of two-dimensional transition metal dichalcogenides(TMDs) materials and improving device performance to desired properties. However, the methods in defect controlcurrently face challenges with overly large operational areas and a lack of precision in targeting specific defects. Therefore,we propose a new method for the precise and universal defect healing of TMD materials, integrating real-time imaging withscanning transmission electron microscopy (STEM). This method employs electron beam irradiation to stimulate the diffusionmigration of surface-adsorbed adatoms on TMD materials grown by low-temperature molecular beam epitaxy (MBE),and heal defects within the diffusion range. This approach covers defect repairs ranging from zero-dimensional vacancydefects to two-dimensional grain orientation alignment, demonstrating its universality in terms of the types of samples anddefects. These findings offer insights into the use of atomic-level focused electron beams at appropriate voltages in STEMfor defect healing, providing valuable experience for achieving atomic-level precise fabrication of TMD materials.
文摘The Lande g-factor of a free atom determines the effective magnetic moment of an electron or atom with both spin and orbital angular momentum,which can be calculated by Lande formula,for a transition metal ion in the crystal field,the spin-orbital interaction can mix the non-zero orbital angular momentum of excited states with the＂pure spin＂ground state,resulting in an effective g-factor.Thus,the ability to probe the fine structure of the g-factor allows us to understand the internal spin properties of a magnetic system,such as the spin-orbital interaction.However,for molecular systems,traditional experimental methods for g-factor measurement,like EPR.
基金supported by the National Natural Science Foundation of China(92361301,22325105,22201159,22171164,and 52261135637)the Instrument Improvement Funds of Shandong University Public Technology Platform(ts20220102).
文摘The manipulation of single atom within the metallic kernel of nanoclusters has attracted considerable attention due to its potentials to elucidate kernel-based structure-property relationships at the single-atom level.Herein,new-designed chiral bialkynyl ligands,have been chosen as protective agents to isolate two pairs of 8-electron superatomic silver nanoclusters,R/S-Ag39 and R/S-Ag40.X-ray diffraction analysis reveals that Ag39 and Ag40 with the same number of chiral ligands,possess a closely analogous silver skeleton but a single-atomic difference.The incorporation of an extra Ag40th atom into Ag40 evokes two significant changes of structure and property compared to Ag39:(i)a reduction in the symmetry of the entire nanocluster,resulting in an enhancement of kernel-related asymmetry g-factor;(ii)a regulation of the transitions(1P→1D and Ligand(π)→1D)of excited state,leading to a second near-infrared(NIR-II,1000-1700 nm)phosphorescent emission red-shift from 1088 to 1150 nm.This work not only provides vital insights into the relationship between structures and ground/excited states chiroptical activities at the single-atom level,but also presents bialkynyl as a promising stabilizing agent for building superatomic metal nanoclusters.
基金the National High Technology Research and Development Program(863 Program No.2006AA04Z320)Excellent Young Scholars Training Grant of Liaoning Province(Grant No.2005220025)
文摘In the fabrication process of nanoelectronic device arrays based on single-wall carbon nanotube(SWCNT),oriented alignment of SWCNTs and property modification of metallic SWCNTs in the array are the key problems to be solved.Pulse gas alignment with substrate downward tilt is proposed to realize the controllable alignment of SWCNTs.Experimental results demonstrate that 84%SWCNTs are aligned in-15°―15°angular to the pulse gas direction.A modified nanomanipulation technology based on atomic force microscope(AFM)is utilized to perform various kinds of SWCNT manipulation,such as SWCNT separation from the"Y"CNT,catalyst removal from the SWCNT end,continual nano buckles fabrication on SWCNT and even stretching to break,which provides a feasible way to modify the size,shape and the electrical property of SWCNTs.
基金supported by the National Natural Science Foundation of China (21525523, 21574048, 21375042, 21405054)the National Basic Research Program of China (2015CB932600, 2013CB933000)+1 种基金the Special Fund for Strategic New Industry Development of Shenzhen, China (JCYJ20150616144425376)1000 Young Talent (to Fan Xia)
文摘The capability to image, as well as control and manipulate single molecules such as nucleic acids(DNA or RNA) can greatly enrich our knowledge of the roles of individual biomolecules in cellular processes and their behavior in native environments. Here we summarize the recent advances of single nucleic acid imaging based on optical observation and force manipulation. We start by discussing the superiority of single molecule image, the central roles nucleic acids play in biosystems, and the significance of single molecule image towards nucleic acids. We then list a series of representative examples in brief to illustrate how nucleic acid of various morphologies has been imaged from different aspects, and what can be learned from such characterizations. Finally,concluding remarks on parts of which should be improved and outlook are outlined.
基金This work was supported by Science Foundation Ireland （Principal Investigator grant number 12/IA/1264, and Walton Visitor Award grant number 08/W.1/B2583）. A.N.C. acknowledges support of the 7th European Community Framework Programme. STM topographic images were processed using WSxM software [39].
文摘Writing at the nanoscale using the desorption of oxygen adatoms from the oxygen-rich MoO2＋x/Mo（110） surface is demonstrated by scanning tunnelling microscopy （STM）. High-temperature oxidation of the Mo（110） surface results in a strained, bulk-like MOO2（010） ultra-thin film with an O-Mo-O trilayer structure. Due to the lattice mismatch between the Mo（110） and the MOO2（010）, the latter consists of well-ordered molybdenum oxide nanorows separated by 2.5 nm. The MoO2（010）/Mo（110） structure is confirmed by STM data and density functional theory calculations. Further oxidation results in the oxygen-rich MoOa^x/Mo（110） surface, which exhibits perfectly aligned double rows of oxygen adatoms, imaged by STM as bright protrusions. These adatoms can be removed from the surface by scanning （or pulsing） at positive sample biases greater than 1.5 V. Tip movement along the surface can be used for controlled lithography （or writing） at the nanoscale, with a minimum feature size of just 3 nm. By moving the STM tip in a predetermined fashion, information can be written and read by applying specific biases between the surface and the tip.
基金S.W.acknowledges the financial support from the National Key R&D Program of China(grant no.2020YFA0309000)the National Natural Science Foundation of China(grant nos.11874258 and 12074247)+5 种基金the Shanghai Municipal Science and Technology Qi Ming Xing Project(grant no.20QA1405100)Fok Ying Tung Foundation for young researchers and SJTU(grant no.21X010200846)This work is also supported by the Ministry of Science and Technology of China(grant nos.2019YFA0308600,2016YFA0301003,and 2016YFA0300403)NSFC(grants nos.21925201,11521404,11634009,92065201,11874256,11790313,and 11861161003)the Strategic Priority Research Program of Chinese Academy of Sciences(grant no.XDB28000000)the Science and Technology Commission of Shanghai Municipality(grants nos.20ZR1414200,2019SHZDZX01,19JC1412701,and 20QA1405100)for partial support.
文摘Topological defects in graphene materials introduce exotic properties with both fundamental importance and technological implications,absent in their defect-free counterparts.Although individual topological defects have been widely studied,collective magnetic behaviors originating from well-organized multiple topological defects remain a great challenge.Here,we examined the collective magnetic properties originating from three pentagon topological defects in truxene-based molecular graphenoids using scanning tunneling microscopy(STM)and non-contact atomic force microscopy.Unpairedπelectrons were introduced into the aromatic topology of truxene molecular graphenoids one by one by dissociating hydrogen atoms at the pentagon defects via atom manipulation.STM measurements,together with density functional theory calculations,suggested that the unpaired electrons were ferromagnetically coupled,forming a collective highspin quartet state of S=3/2.Our work demonstrates that collective spin ordering could be realized through engineering regular patterned topological defects in molecular graphenoids,providing a new platform for designing one-dimensional ferromagnetic spin chains and two-dimensional ferromagnetic networks.
