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1、Structure Determination of Graphene by TEMXIAO Gaobo11900474ROutline Brief introduction about graphene Review of TEM How scientists use TEM to study the structure of graphene SummaryGraphene is a one-atom-thick planar sheet of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal la
2、ttice.Molecular structure of grapheneHigh resolution transmission electron microscope images of grapheneGraphene is as the strongest material ever measured,some 200 times stronger than structural steelElectrical conductivity97.7%transmittance of white lightThermal conductivityOutline Brief introduct
3、ion about graphene Review of TEM How scientists use TEM to study the structure of graphene SummaryTEM-Transmission electron microscopeWorking modes of TEMu Diffraction modeu Imaging mode 1 Amplitude contrast A)mass/thickness B)diffraction 2 Phase contrastDiffraction modeFor a thin sheet of single cr
4、ystal,its reciprocal lattice is a set of parallel rodsFor polycrystalline specimen,its reciprocal lattice is series of concentric spheresThe diffraction pattern can be seen as a magnified view of a planar section through the reciprocal lattice normal to the incident beam.Amplitude contrast Phase con
5、trastImanging moderelatively low resolutions(1nm)very high resolutions(1nm)Outline Brief introduction about graphene Review of TEM How scientists use TEM to study the structure of graphene SummaryJ.C.Meyer,2007,Nature lettersMicrometre-sized metallic scaffoldGrapheneFolded regionBright-field TEM ima
6、ge of suspended grapheneMonolayer graphene,a fold exhibits only one dark lineBilayer graphene,a fold exhibits two dark lines2nm 2nmFor single-layer graphene,intensities in reciprocal space are continuous rods For two-layer samples,an intensity variation along the rods is presentJ.C.Meyer,2007,Solid
7、State CommunicationsSingle-layer graphene Bilayer graphene(AB stacked)atomically flatcorrugatedor?0o14o26oDiffraction pattern of graphene at different incident anglesJ.C.Meyer,2007,Nature lettersReciprocal lattice of flat grapheneReciprocal lattice of corrugated grapheneThe increase of diffraction s
8、pot size can be explained by a corrugated surface,whose reciprocal lattice is a series of cone shaped volumes.J.C.Meyer,2007,Nature lettersIncreasing spot size at larger incident angleBy using aberration-correction in combination with a monochromator,1-resolution is achieved at an acceleration volta
9、ge of only 80 kV.J.C.Meyer,2008,Nano lettersLattice with defects Configuration of defects1nmalar.Girit,2009,ScienceDynamics of carbon atoms at the edge of a holeCarbon adatomHydrogen adatoms on the same sampleJ.C.Meyer,2008,NatureHydrogen adatomsCarbon adatomHydrogen adatomIndividual carbon adatom o
10、n graphene2nm2nmSummaryIn the past,TEM has been used to differentiate single-layer graphene.to study the surface morphology.to study the lattice defects.to investigate individual foreign atoms on graphene.References 1 A.Fasolino et al.,Intrinsic ripples in graphene,NATURE MATERIALS2007,6(11),858-861
11、.2 AC Ferrari et al.,Raman spectrum of graphene and graphene layers,Phys.Rev.Lett.2006,97(18),.3 CO Girit et al.,Graphene at the Edge:Stability and Dynamics,Science 2009,323(5922),1705-1708.4 A.V.Krasheninnikov et al.,Engineering of nanostructured carbon materials with electron or ion beams,Nature m
12、aterials 2007,6(10),723.5 Z.Liu et al.,Open and Closed Edges of Graphene Layers,Phys.Rev.Lett.2009,102(1),.6 J.C.Meyer et al.,On the roughness of single-and bi-layer graphene membranes,Solid State Communications,2007,143(12):101.7 JC Meyer et al.,The structure of suspended graphene sheets,Nature 200
13、7,446(7131),60-63.8 JC Meyer et al.,Imaging and dynamics of light atoms and molecules on graphene,Nature 2008,454(7202),319-322.9 JC Meyer et al.,Direct Imaging of Lattice Atoms and Topological Defects in Graphene Membranes,NANO LETTERS 2008,8(11),3582-3586.10 W.Moritz et al.,Structure Determination
14、 of the Coincidence Phase of Graphene on Ru(0001),Phys.Rev.Lett.2010,104(13),.11 KS Novoselov et al.,Electric field effect in atomically thin carbon films,Science 2004,306(5696),666-669.12 C.Stampfer et al.,Energy Gaps in Etched Graphene Nanoribbons,Phys.Rev.Lett.2009,102(5),.13 Knut W.Urban and Knut W.Urban,Studying atomic structures by aberration-corrected transmission electron microscopy,Science(New York,N.Y.)2008,321(5888),506.14 Knut W.Urban and Knut W.Urban,Electron microscopy:The challenges of graphene,Nature materials 2011,10(3),165.Thanks for your attention