透射電子顯微鏡TEM

透射電子顯微鏡TransmissionElectronMicroscopy當代分析措施與技術目錄Contents透射電子顯微鏡21歷史History2原理Background3構造Components4制備Preparation5應用Application歷史History最初研究Initialdevelopment透射電子顯微鏡3ErnstAbbe(*23.Januar1840;?14.Januar1905),deutscherAstronom對物體細節(jié)的分辨率受到用于成像的光波波長的限制Theabilitytoresolvedetailinanobjectwaslimitedapproximatelybythewavelengthofthelightusedinimaging光學顯微鏡分辨率僅在微米級limitstheresolutionofanopticalmicroscopetoafewhundrednanometersAugustK?hler(March4,1866–March12,1948),GermanyPhysicistMoritzvonRohr(4April1868–20June1940),GermanyPhysicistJuliusPlücker(16July1801–22May1868)GermanmathematicianandphysicistFerdinandBraun(4April1868–20June1940),GermanyPhysicist185818971891192619281931JuliusPlücker磁場可使陰極射線彎曲Thedeflectionof"cathoderays"(electrons)waspossiblebytheuseofmagneticfieldsRiecke使用磁場能夠使陰極射線聚焦Thecathoderayscouldbefocusedbymagneticfields,allowingforsimplelensdesignsAugustK?hlerandMoritzRohr研制出能夠將極限辨別率提升約一倍的紫外光顯微鏡Developmentsintoultraviolet(UV)microscopesallowedforanincreaseinresolvingpowerofaboutafactoroftwoFerdinandBraun陰極射線示波器Built

primitivecathoderayoscilloscopes(CROs)intendedasameasurementdeviceAdolfMatthias&MaxKnoll考慮了透鏡設計和示波器的列排列，研制能夠用于產(chǎn)生低放大倍數(shù)（接近1:1）的電子光學原件AttemptedtoobtaintheparametersthatcouldbeoptimizedtoallowforconstructionofbetterCROs,aswellasthedevelopmentofelectronopticalcomponentswhichcouldbeusedtogeneratelowmagnification(nearly1:1)imagesHansBusch制鏡者方程在合適的條件下能夠用于電子射線Thelensmaker'sequationcouldbeapplicabletoelectronsunderappropriateassumptionsMaxKnollGroup成功的產(chǎn)生了在陽極光圈上放置的網(wǎng)格的電子放大圖像——第一臺電子顯微鏡SuccessfullygeneratedmagnifiedimagesofmeshgridsplacedovertheanodeapertureArguablythefirstelectronmicroscope1LouisdeBroglie

(15

August1892–19

March1987),FranchPhysicistAwardedNobelPrizeinPhysics(1929)LouisdeBroglie,1927電子作為物質粒子的波動特征Thewavenatureofelectronshadnotbeenfullyrealizeduntilthepublicationofthe

DeBrogliehypothesis

in1927電子波的波長比光波波長小了若干數(shù)量級，理論上允許人們觀察原子尺度的物質TheDeBrogliewavelengthofelectronswasmanyordersofmagnitudesmallerthanthatforlight,theoreticallyallowingforimagingatatomicscales歷史History辨別率的提升ImprovingResolution透射電子顯微鏡4MaxKnoll&ErnstRuska1932建造一種新的電子顯微鏡以直接觀察插入顯微鏡的樣品Constructedanewelectronmicroscopefordirectimagingofspecimens

insertedintothemicroscope1933通過對棉纖維成像正式地證明了TEM的高分辨率ByusingimagesofcottonfibersdemonstratedthehighresolutionofTEM第一臺商用TEMThefirstcommercialelectronmicroscope

wasinstalledinthePhysicsdepartmentofIGFarben-Werke1936改進TEM的成像效果，尤其是對生物樣品的成像TheimprovementofTEMimagingproperties,particularlywithregardtobiologicalspecimensThefirstpracticalTEM,originallyinstalledatIGFarben-WerkeandnowondisplayattheDeutschesMuseuminMunich,Germany1歷史History進一步研究FurtherResearch透射電子顯微鏡51AfterWorldWarⅡErnstRuskaatSIMENS生產(chǎn)了第一臺能夠放大十萬倍的顯微鏡Producedthefirstmicroscopewith100kmagnification1942第一屆電子顯微鏡國際會議(Delft)Thefirstinternationalconferenceinelectronmicroscopy1950InParis1954

InLondon1970AlbertCrewe(ChicagoUniversity,USA)發(fā)明了場發(fā)射槍，添加了高質量的物鏡，發(fā)明了現(xiàn)代的掃描透射電子顯微鏡Developedthefieldemissiongun

andaddedahighqualityobjectivelenstocreatethemodernSTEM(ScanningTransmissionElectronMicroscopy)ASTEMequippedwitha3rd-ordersphericalaberrationcorrector目錄Contents透射電子顯微鏡61歷史History2原理Background3構造Components4制備Preparation5應用Application原理Background電子Electron透射電子顯微鏡72

光學顯微鏡所能達成的最大辨別率受到如下條件的限制Themaximumresolutionthatonecanobtainwithalightmicroscopehasbeenlimitedby照射在樣品上的光子波長λthewavelengthofthephotonsthatarebeingusedtoprobethesampleλ光學系統(tǒng)的數(shù)值孔徑，NAthenumericalapertureofthesystemNA相對論修正Anadditionalcorrectiontoaccountforrelativisticeffects透射出的電子束包具有電子強度、相位、以及周期性的信息，這些信息將被用于成像Thetransmittedbeamcontainsinformationaboutelectrondensity,phaseandperiodicity.Thisbeamisusedtoformanimage原理Background電子源SourceFormation透射電子顯微鏡82

材料MaterialsTungstenorLaB6形制ShapesHairpin-stylefilamentSmallspike-shapedfilament

HairpinstyletungstenfilamentSinglecrystalLaB6filament高壓電源highvoltagesource(typically~100–300kV)熱電子發(fā)射

或場電子發(fā)射thermionicorfieldelectronemission兩種物理現(xiàn)象TwoPhysicalEffects運動的電子在磁場中將會根據(jù)右手定則受到洛倫茲力的作用Theinteractionofelectronswithamagneticfieldwillcauseelectronstomoveaccordingtothelefthandrule使用磁場能夠形成不同聚焦能力的磁透鏡Theuseofmagneticfieldsallowsfortheformationofamagneticlensofvariablefocusingpower原理Background電子光學設備與成像設備Optical&Display透射電子顯微鏡92

透鏡Lens

電子束聚焦Beamconvergence三級透鏡Threestagesoflensing

聚焦透鏡Thecondenserlenses

物鏡Theobjectivelenses

投影透鏡Theprojectorlenses熒光屏FluorescentScreenZnS(10–100

μm)FilmsCCDLayoutofopticalcomponentsinabasicTEM目錄Contents透射電子顯微鏡101歷史History2原理Background3構造Components4制備Preparation5應用Application構造Components真空系統(tǒng)VacuumSystem(No.11)透射電子顯微鏡113

作用Effects在陰極和地之間加以很高的電壓，而不擊穿空氣產(chǎn)生電弧Theallowanceforthevoltagedifferencebetweenthecathodeandthegroundwithoutgeneratinganarc將電子和空氣原子的撞擊頻率減小到能夠忽視的量級Toreducethecollisionfrequencyofelectronswithgasatomstonegligiblelevels構成Components旋片泵或隔膜泵RotaryVanePumporDiaphragmPumps低真空Settingasufficientlylowpressure渦輪分子泵或擴散泵Turbo-molecularorDiffusionpump高真空Establishinghighvacuumlevel門閥或差動泵GatevalvesorDifferentialpumpingaperture隔離電子槍與主腔室Isolatedthegunfromthemainchamber離子泵或吸氣材料IonpumporGettermaterialTheelectronsourceoftheTEMisatthetop,wherethelensingsystem(4,7and8)focusesthebeamonthespecimenandthenprojectsitontotheviewingscreen(10).Thebeamcontrolisontheright(13and14)構造Components樣品臺SpecimenStage(No.6)透射電子顯微鏡123

尺寸Size直徑3.05mm的環(huán)形，其厚度和網(wǎng)格大小不不小于100微米StandardTEMgridsizesarea3.05mmdiameterring,withathicknessandmeshsizerangingfromafewto100μm內部的網(wǎng)格區(qū)域直徑約2.5mmThesampleisplacedontotheinnermeshedareahavingdiameterofapproximately2.5mm材料Materials:Cu,Mo,Au,Pt設計Design側入式theSide-entryversion頂入式theTopentryversionTheelectronsourceoftheTEMisatthetop,wherethelensingsystem(4,7and8)focusesthebeamonthespecimenandthenprojectsitontotheviewingscreen(10).Thebeamcontrolisontheright(13and14)構造Components電子槍ElectronGun(No.2)透射電子顯微鏡133

構成Consistance燈絲、偏置電路、韋乃特陰極、陽極theFilament,aBiasingcircuit,aWehneltcap,andanExtractionanode材料Materials:Cu,Mo,Au,Pt設計Design側入式theSide-entryversion頂入式theTopentryversionTheelectronsourceoftheTEMisatthetop,wherethelensingsystem(4,7and8)focusesthebeamonthespecimenandthenprojectsitontotheviewingscreen(10).Thebeamcontrolisontheright(13and14)構造Components電子透鏡ElectronLens(No.4)透射電子顯微鏡143

構成Consistance外殼、磁線圈、磁極、極靴、外部控制電路theyoke,themagneticcoil,thepoles,thepolepiece,andtheexternalcontrolcircuitryTheelectronsourceoftheTEMisatthetop,wherethelensingsystem(4,7and8)focusesthebeamonthespecimenandthenprojectsitontotheviewingscreen(10).Thebeamcontrolisontheright(13and14)目錄Contents透射電子顯微鏡151歷史History2原理Background3構造Components4制備Preparation5應用Application制備Preparation透射電子顯微鏡164

要求Requirement薄片在納米尺度TEMspecimensarerequiredtobeatmosthundredsofnanometersthick措施Methods切片加工法TissueSectioning染色加工法SampleStaining機械加工法MechanicalMilling化學腐蝕法ChemicalEtching離子刻蝕法IonEtching復制法ReplicationChemicalEtchingReplicationIonEtchingMechanicalMillingSampleStaningTissueSectioning工具Tools玻璃或金剛石GlassorDiamonds優(yōu)勢Advantage取得薄而最低程度變形的樣本toobtainthin,minimallydeformedsamples局限Limitation對軟樣品傷害極大theheavydamageinducedinthelesssoftsamplesAdiamondknifebladeusedforcuttingultrathinsections(typically70to350nm)fortransmissionelectronmicroscopy工具Tools重金屬HeavyMental(Os,Pb,Au,U)優(yōu)勢Advantage經(jīng)過著色提升吸收光線來增強觀察細節(jié)Enhancethedetailsinlightmicroscopesamplesstains