Metal-supported ultrathin ferrous oxide(FeO)has attracted immense interest in academia and industry due to its widespread applications in heterogeneous catalysis.However,chemical insight into the local structural char...Metal-supported ultrathin ferrous oxide(FeO)has attracted immense interest in academia and industry due to its widespread applications in heterogeneous catalysis.However,chemical insight into the local structural characteristics of FeO,despite its critical importance in elucidating structure−property relationships,remains elusive.In this work,we report the nanoscale chemical probing of gold(Au)-supported ultrathin FeO via ultrahigh-vacuum tip-enhanced Raman spectroscopy(UHV-TERS)and scanning tunneling microscopy(STM).For comparative analysis,single-crystal Au(111)and Au(100)substrates are used to tune the interfacial properties of FeO.Although STM images show distinctly different moirésuperstructures on FeO nanoislands on Au(111)and Au(100),TERS demonstrates the same chemical nature of FeO by comparable vibrational features.In addition,combined TERS and STM measurements identify a unique wrinkled FeO structure on Au(100),which is correlated to the reassembly of the intrinsic Au(100)surface reconstruction due to FeO deposition.Beyond revealing the morphologies of ultrathin FeO on Au substrates,our study provides a thorough understanding of the local interfacial properties and interactions of FeO on Au,which could shed light on the rational design of metal-supported FeO catalysts.Furthermore,this work demonstrates the promising utility of combined TERS and STM in chemically probing the structural properties of metal-supported ultrathin oxides on the nanoscale.展开更多
Two-dimensional(2D)honeycomb-like materials have been widely studied due to their fascinating properties.In particular,2D honeycomb-like transition metal monolayers,which are good 2D ferromagnet candidates,have attrac...Two-dimensional(2D)honeycomb-like materials have been widely studied due to their fascinating properties.In particular,2D honeycomb-like transition metal monolayers,which are good 2D ferromagnet candidates,have attracted intense research interest.The honeycomb-like structure of hafnium,hafnene,has been successfully fabricated on the Ir(111)substrate.However,its electronic structure has not yet been directly elucidated.Here,we report the electronic structure of hafnene grown on the Ir(111)substrate using angle-resolved photoemission spectroscopy(ARPES).Our results indicate that the presence of spin-orbit coupling and Hubbard interaction suppresses the earlier predicted Dirac cones at the K points of the Brillouin zone.The observed band structure of hafnene near the Fermi level is very simple:an electron pocket centered at theΓpoint of the Brillouin zone.This electron pocket shows typical parabolic dispersion,and its estimated electron effective mass and electron density are approximately 1.8_(me)and 7×10^(14)cm^(-2),respectively.Our results demonstrate the existence of 2D electron gas in hafnene grown on the Ir(111)substrate and therefore provide key information for potential hafnene-based device applications.展开更多
With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to...With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to electrodes,of TMD heterostructure devices can be significantly tailored by employing the functional layers,called interlayer engineering.At the interface between different TMD layers,the dangling-bond states normally exist and act as traps against charge carrier flow.In this study,we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states,as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure.The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface,as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations.The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures.Thus,this technique provides an effective way for optimizing the interface contact,the crucial issue exists in two-dimensional electronic community.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
基金support from the National Science Foundation(DMR-2211474).
文摘Metal-supported ultrathin ferrous oxide(FeO)has attracted immense interest in academia and industry due to its widespread applications in heterogeneous catalysis.However,chemical insight into the local structural characteristics of FeO,despite its critical importance in elucidating structure−property relationships,remains elusive.In this work,we report the nanoscale chemical probing of gold(Au)-supported ultrathin FeO via ultrahigh-vacuum tip-enhanced Raman spectroscopy(UHV-TERS)and scanning tunneling microscopy(STM).For comparative analysis,single-crystal Au(111)and Au(100)substrates are used to tune the interfacial properties of FeO.Although STM images show distinctly different moirésuperstructures on FeO nanoislands on Au(111)and Au(100),TERS demonstrates the same chemical nature of FeO by comparable vibrational features.In addition,combined TERS and STM measurements identify a unique wrinkled FeO structure on Au(100),which is correlated to the reassembly of the intrinsic Au(100)surface reconstruction due to FeO deposition.Beyond revealing the morphologies of ultrathin FeO on Au substrates,our study provides a thorough understanding of the local interfacial properties and interactions of FeO on Au,which could shed light on the rational design of metal-supported FeO catalysts.Furthermore,this work demonstrates the promising utility of combined TERS and STM in chemically probing the structural properties of metal-supported ultrathin oxides on the nanoscale.
基金This work is supported by the National Key Research and Development Program of China(Nos.2017YFA0303600 and 2020YFA0308800)the National Natural Science Foundation of China(Nos.11974364,11674367,U2032207,92163206,11974045,and 61725107)+2 种基金the Natural Science Foundation of Zhejiang,China(No.LZ18A040002)the Ningbo Science and Technology Bureau(No.2018B10060)S.L.H.would like also to acknowledge the Ningbo 3315 program.
文摘Two-dimensional(2D)honeycomb-like materials have been widely studied due to their fascinating properties.In particular,2D honeycomb-like transition metal monolayers,which are good 2D ferromagnet candidates,have attracted intense research interest.The honeycomb-like structure of hafnium,hafnene,has been successfully fabricated on the Ir(111)substrate.However,its electronic structure has not yet been directly elucidated.Here,we report the electronic structure of hafnene grown on the Ir(111)substrate using angle-resolved photoemission spectroscopy(ARPES).Our results indicate that the presence of spin-orbit coupling and Hubbard interaction suppresses the earlier predicted Dirac cones at the K points of the Brillouin zone.The observed band structure of hafnene near the Fermi level is very simple:an electron pocket centered at theΓpoint of the Brillouin zone.This electron pocket shows typical parabolic dispersion,and its estimated electron effective mass and electron density are approximately 1.8_(me)and 7×10^(14)cm^(-2),respectively.Our results demonstrate the existence of 2D electron gas in hafnene grown on the Ir(111)substrate and therefore provide key information for potential hafnene-based device applications.
基金We acknowledged the financial support from the Beijing Natural Science Foundation(Nos.Z190006 and 4192054)the National Natural Science Foundation of China(Nos.61725107,11622437,61674171,11974422,61761166009,and 61888102)+3 种基金the National Key Research&Development Projects of China(Nos.2016YFA0202301,2019YFA0308000,and 2018YFE0202700)the Fundamental Research Funds for the Central Universities,China and the Research Funds of Renmin University of China(Nos.16XNLQ01 and 19XNQ025)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB30000000 and XDB28000000)Calculations were performed at the Physics Lab of High-Performance Computing of Renmin University of China and Shanghai Supercomputer Center.
文摘With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to electrodes,of TMD heterostructure devices can be significantly tailored by employing the functional layers,called interlayer engineering.At the interface between different TMD layers,the dangling-bond states normally exist and act as traps against charge carrier flow.In this study,we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states,as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure.The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface,as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations.The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures.Thus,this technique provides an effective way for optimizing the interface contact,the crucial issue exists in two-dimensional electronic community.
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.
