第4章表面分析手段1SEMppt课件.ppt

第四章 表面分析手段 2015 4 ComplexityofRealSurfaces 复杂性 BEAConfidential 3 是英雄还是装备 这不是一个问题 BEAConfidential 4 选择学校的另一个标准 分析测试中心 BEAConfidential 5 选择学校的另一个标准 分析测试中心 BEAConfidential 6 选择学校的另一个标准 分析测试中心 BEAConfidential 7 选择学校的另一个标准 分析测试中心 BEAConfidential 8 选择学校的另一个标准 分析测试中心 BEAConfidential 9 BEAConfidential 10 表面分析的两个方面SurfaceSensitivityandSpecificity Twomajordifficultieswithsurfacesciencestudies a Absolutenumberofatomsinsurfaceissmall sensitivity灵敏度 Typicalsinglecrystalsurfaceof1cm2areacontains 1015atoms 10 9moles表面原子的绝对数量是比较小的 典型单晶1cm2的面积上 只有1015或者说10 9个原子 SurfaceSensitivityandSpecificity Twomajordifficultieswithsurfacesciencestudies b Ratioofsurfaceatomstobulkatomsissmall specificity特异性 Typicalsurface bulkatomratioinsolid 10 7 10 8 dependingonsurfacestructure needtobeabletoseparatesurfacesignalfrombulksignal 表面原子百分比和本体原子的比例很小 所以需要讲表面原子的信号和本体信号区分开来 SurfaceSciencemethods Experimentalsurfacescience AB C AC B Methodsforsurfaceanalysis Twomajorinstrumentationtechniquesforsurfaceanalysis Surfacemicroscopy 表面形貌 a imagingthesurfaceanddeterminingthemorphology atomiccrystallinestructure andotherphysicalpropertiesandfeaturesatdifferentsizescale nanometerstomicrometers 在纳米到微米的尺度上对表面进行拍照 测定其形貌 晶体结构和其它物理性质 二维 b 3 dimensionalsurfacestructurewithhighresolution 高分辨率的三维表面结构 Methodsforsurfaceanalysis Twomajorinstrumentationtechniquesforsurfaceanalysis 2 Surfacespectroscopy 表面光谱 a identifyingthesurfacechemicalspeciesanddeterminingtheconcentrations分辨表面化学组成 确定其浓度b providingbothqualitativeandquantitative lessused informationaboutthecompositionofsurfacelayer提供表面层组成的定性定量信息 afewtoafewtensof depth SurfaceAnalyticalTechniques Modernsurfaceanalyticaltechniquesarecharacterizedbyabeams 束 in beamsoutorprobe 探针 measureapproach SurfaceAnalyticalTechniques Incidentbeam probeinteractswithsurfacelayer whileoutputbeamcarryingthemeasuredsurfaceinformationisanalyzed 起始的 束 或者探针和表面层发生相互作用 而表面释放的 束 携带表面的信息以供分析 Surface 那些 beam 可供使用 4 1Scanningelectronmicroscopy扫描电子显微镜 Scanningelectronmicroscopes SEMs inventedinthe1930s letusseeobjectsassmallas10nanometers 4 2ScanningelectronmicroscopyNoblePrize Itisamicroscopethatproducesanimagebyusinganelectronbeamthatscansthesurfaceofaspecimeninsideavacuumchamber SEM是用在真空腔中用电子束扫描样品表面 从而得到图像的显微镜 4 1ScanningelectronmicroscopyWhatisSEM WhatcanwestudyinaSEM 我们从SEM可以得到什么 Morphology形貌Chemistry化学成分 4 1ScanningelectronmicroscopyWhatisSEM 4 1ScanningelectronmicroscopyWhatdoesitlookslike AFMCantileverTip AntHead BloodCells DiamondThinFilm NumerousMultifacetedMicro crystals Microstructureofaplaincarbonsteelthatcontains0 44wt ofcarbon CalciumPhosphateCrystal 4 1Scanningelectronmicroscopy 作用原理 光电效应Thescanningelectronmicroscope SEM usesafocusedbeamofhigh energyelectronstogenerateavarietyofsignalsatthesurfaceofsolidspecimens SEM用聚焦高能电子束来在样品表面产生各种信号 4 1Scanningelectronmicroscopy Thesignalsthatderivefromelectron sampleinteractionsrevealinformationaboutthesampleincludingexternalmorphology texture chemicalcomposition andcrystallinestructureandorientationofmaterialsmakingupthesample 通过电子 样品相互作用释放关于样品形貌 化学组成 晶体结构等信息 4 1Scanningelectronmicroscopy 4 1ScanningelectronmicroscopyWheredoesthesignalscomefrom Diameteroftheinteractionvolumeislargerthantheelectronspot 电子轰击点的面积比其作用体积的直径小 4 1Scanningelectronmicroscopy Signalsfromthesample Incomingelectrons入射电子 Secondaryelectrons二次电子 Backscatteredelectrons背散射电子 Augerelectrons俄歇电子 X rays Cathodo luminescence light 阴极荧光 Sample 4 1ScanningelectronmicroscopySecondaryelectrons SE 二次电子 GeneratedfromthecollisionbetweentheincomingelectronsandthelooselybondedouterelectronsLowenergyelectrons 10 50eV OnlySEgeneratedclosetosurfaceescape topographic 地形上的 informationisobtained 只有表面才逸出二次电子NumberofSEisgreaterthanthenumberofincomingelectrons 二次电子数量比入射电子数目多 4 1ScanningelectronmicroscopyBackscatteredelectrons BSE 背散射电子 Afractionoftheincidentelectronsisretarded 阻止 bytheelectro magneticfieldofthenucleusandifthescatteringangleisgreaterthan180 theelectroncanescapefromthesurfaceHighenergyelectrons elasticscattering 弹性碰撞 能量高 FewerBSEthanSE背散射电子比二次电子少 4 1ScanningelectronmicroscopyBSEvsSE SEproduceshigherresolutionimagesthanBSE二次电子提供更高分辨率Byplacingthesecondaryelectrondetectorinsidethelens mainlySEaredetectedResolutionof1 2nmispossible BEAConfidential 32 二次电子 背散射电子 4 1ScanningelectronmicroscopyX rays Photonsnotelectrons光子而非电子EachelementhasafingerprintX raysignal每种元素都有X光信号指纹 元素定性定量分析 PoorerspatialresolutionthanBSEandSE分辨率差 4 1ScanningelectronmicroscopyX rays RelativelyfewX raysignalsareemittedandthedetectorisinefficientX射线信号相对较少relativelylongsignalcollectingtimesareneeded采集时间长 4 1ScanningelectronmicroscopyX rays Mostcommonspectrometer EDS energy dispersivespectrometer 最常用光谱仪EDSSignaloverlapcanbeaproblem信号重叠 Fig 2EDSgraphicofuncoatedAZ91magnesiumalloy HikmetAltun HakanSinici CorrosionbehaviourofmagnesiumalloyscoatedwithTiNbycathodicarcdepositioninNaClandNa2SO4solutions MaterialsCharacterization Volume59 Issue3 2008 266 270 Fig 3EDSgraphicofTiNcoatedAZ91magnesiumalloy HikmetAltun HakanSinici CorrosionbehaviourofmagnesiumalloyscoatedwithTiNbycathodicarcdepositioninNaClandNa2SO4solutions MaterialsCharacterization Volume59 Issue3 2008 266 270 4 1ScanningelectronmicroscopyX rays Wecananalyzeoursampleindifferentmodes模式多chemicalconcentrationmap elementalmapping spotanalysislinescan Fig 8FESEMimageandEDXspectrumofRh ZrO2filmspreparedataRh Zrsourcemolarratioof0 05 depositiontemperatureof1180K AnarrowindicatesoneofRhnanoparticle 二氧化锆的薄膜 AkihiroHonda TeiichiKimura AkihikoIto TakahiGoto Rh nanoparticle dispersedZrO2filmspreparedbylaserchemicalvapordeposition SurfaceandCoatingsTechnology Volume206 Issues11 12 2012 3006 3010 spotanalysis点扫描 Fig 5 A SEMimageofexternalsurfaceoftheCo SiO2 Z Sp Pd B cross sectionSEMimageoftheCo SiO2 Z Sp PdwiththeintensityofPd SiandAlX raysignalsfromtheEDSlinescan C externalsurfaceEDSanalysisresultoftheCo SiO2 Z Sp 二氧化硅薄膜 YuzhouJin RuiqinYang YasuhiroMori JianSun AkiraTaguchi YoshiharuYoneyama TakayukiAbe Noritat PreparationandperformanceofCobasedcapsulecatalystwiththezeoliteshellsputteredbyPdfordirectisoparaffinsynthesisfromsyngas AppliedCatalysisA General Volume456 2013 75 81 linescan线扫描 Fig 1SectionoftheCa Mg Znphasediagram accordingtoRef 43 CompositionsreportedbySenkovandScott 2 aremarkedbybluecircles andthenewhighzinc Ca Mg Zn金属玻璃的腐蚀 J D Cao N T Kirkland K J Laws N Birbilis M Ferry Ca Mg Znbulkmetallicglassesasbioresorbablemetals ActaBiomaterialia Volume8 Issue6 2012 2375 2383 mapping 4 1ScanningelectronmicroscopySummary Signals Secondaryelectrons SE mainlytopographyLowenergyelectrons highresolution高分辨率SurfacesignaldependentoncurvatureBackscatteredel