Taw qhia rau Kev Ntsuas Cov Ntsiab Cai ntawm Kev Sib Txuas Electron Microscopy
Cov qauv ntawm lub tshuab hluav taws xob xa hluav taws xob muaj ob ntu: qhov tseem ceeb yog lub teeb pom kev zoo, lub teeb pom kev zoo thiab kev soj ntsuam studio; qhov chaw pabcuam yog lub tshuab nqus tsev thiab lub tshuab hluav taws xob.
1. Teeb pom kev zoo
Lub kaw lus tau muab faib ua ob ntu: rab phom electron thiab condenser. Ib rab phom electron muaj ib lub filament (cathode), kab sib chaws, thiab anode. Cov cua sov filament emits ib lub teeb ntawm electrons. Thaum ib tug voltage yog siv rau lub anode, cov electrons yog ceev. Lub peev xwm sib txawv ntawm anode thiab cathode yog tag nrho accelerating voltage. Accelerated electrons nrog lub zog yog ejected los ntawm qhov nyob rau hauv lub anode phaj. Lub zog ntawm cov hluav taws xob hluav taws xob hluav taws xob muaj feem cuam tshuam rau qhov nrawm nrawm, thiab daim phiaj ua lub luag haujlwm ntawm kev tswj cov duab ntawm lub teeb hluav taws xob. Lub teeb hluav taws xob muaj qhov sib txawv ntawm lub kaum ntse ntse. Tom qab kho lub condenser lens, ib tug parallel electron beam nrog ib tug me me los yog zero divergence kaum yuav pom tau. Qhov ceev tam sim no (beam tam sim no) ntawm lub teeb hluav taws xob tuaj yeem hloov kho los ntawm kev kho qhov tam sim no ntawm lub lens condenser.
Qhov loj ntawm cheeb tsam ntawm cov qauv uas yuav tsum tau illuminated yog hais txog qhov magnification. Qhov siab dua qhov kev nthuav dav, qhov me me ntawm thaj chaw illuminated. Yog li ntawd, ib tug finer electron beam yuav tsum tau irradiate tus qauv. Lub beam qhov luaj li cas ntawm cov hluav taws xob hluav taws xob ncaj qha tawm los ntawm rab phom electron loj dua thiab qhov sib txuam kuj tsis zoo. Txhawm rau siv cov khoom siv hluav taws xob no zoo dua thiab tau txais cov kab hluav taws xob hluav taws xob nrog lub teeb ci siab thiab kev sib raug zoo kom ua tau raws li qhov xav tau ntawm kev xa hluav taws xob hluav taws xob ntawm qhov sib txawv, cov kab hluav taws xob hluav taws xob tawm los ntawm rab phom electron yuav tsum tau sib txuas ntxiv kom muab cov kab sib txawv. qhov loj. , kwv yees li cov kab teeb pom kev sib luag. Txoj hauj lwm no feem ntau ua tiav los ntawm ob lub tshuab electromagnetic hu ua condensers. Nyob rau hauv daim duab, C1 thiab C2 sawv cev rau thawj condenser thiab thib ob condenser, feem. C1 feem ntau tseem zoo li qub, thiab nws lub luag haujlwm yog los teeb tsa kev sib tshuam ntawm cov phom electron kom txo qhov loj ntawm daim duab los ntawm ntau tshaj qhov kev txiav txim ntawm qhov loj. Tsis tas li ntawd, cov cuab yeej beam qaij tau nruab rau hauv lub teeb pom kev zoo, uas tuaj yeem yooj yim qaij lub teeb hluav taws xob nyob rau hauv thaj tsam ntawm 2 degree mus rau 3 degree kom pom cov qauv ntawm qhov sib txawv qaij kaum.
2. Kev ntsuas qhov system
Lub kaw lus suav nrog cov khoom siv hluav taws xob xws li cov qauv chamber, lub hom phiaj lens, daim iav nruab nrab, qhov sib txawv diaphragm, diffraction diaphragm, projection lens, thiab lwm yam. Cov qauv chamber muaj lub tshuab ua kom lub tshuab nqus tsev ntawm lub cev tseem ceeb tsis puas thaum lub sij hawm hloov pauv ntau zaus. . Cov qauv tuaj yeem txav mus rau hauv X thiab Y cov lus qhia txhawm rau nrhiav txoj haujlwm kom pom. Lub parallel electron beam tau los ntawm converging lens irradiates tus qauv thiab nqa cov ntaub ntawv qhia txog cov yam ntxwv ntawm tus qauv tom qab dhau los ntawm cov qauv. Cov duab hluav taws xob yog tsim nyob rau hauv qhov kev txiav txim ntawm lub hom phiaj lens thiab qhov sib piv diaphragm, thiab tom qab ntawd nthuav dav los ntawm daim iav nruab nrab thiab qhov projection lens. Cov duab hluav taws xob zaum kawg tau txais ntawm lub vijtsam fluorescent.
Lub illumination system muab ib coherent illuminating electron beam, uas nqa cov qauv ntaub ntawv ntawm tus qauv tom qab dhau los ntawm cov qauv thiab propagates nyob rau hauv sib txawv cov lus qhia (piv txwv li, thaum muaj ib tug siv lead ua ntsej muag pab pawg neeg txaus siab rau Bragg sib npaug, 2 lub ces kaum yuav generated nyob rau hauv lub illumination system. cov kev taw qhia hla qhov xwm txheej beam diffracted beam). Lub hom phiaj yuav los ntawm ntau qhov chaw ntawm cov qauv nrog tib cov kev taw qhia ntawm kev nthuav tawm. Electrons converge mus rau hauv ib qho chaw ntawm lub dav hlau focal rov qab, thiab cov electrons mus rau hauv cov lus qhia sib txawv tsim cov chaw sib txawv raws li. Ib tug ncaj beam ntawm xoom tawg lub kaum sab xis converges ntawm lub focal point ntawm lub hom phiaj, tsim ib tug central chaw. Nyob rau hauv txoj kev no, tus qauv diffraction yog tsim nyob rau sab nraum qab focal dav hlau ntawm lub hom phiaj. Nyob rau hauv daim duab dav hlau ntawm lub hom phiaj, cov kab hluav taws xob electron recombine rau coherent imaging. Los ntawm kev kho lub lens tam sim no ntawm lub lens nruab nrab, cov khoom dav hlau ntawm lub lens nruab nrab thiab lub dav hlau focal ntawm lub hom phiaj lens yog coincident, uas tuaj yeem pom ntawm lub vijtsam fluorescent. Cov qauv diffraction tau los saum toj no tuaj yeem ua rau cov khoom dav hlau ntawm lub lens nruab nrab sib npaug nrog cov duab dav hlau ntawm lub hom phiaj lens, yog li tau txais cov duab microscopic. Los ntawm kev koom tes ntawm ob lub iav nruab nrab, qhov ntev thiab qhov loj ntawm lub koob yees duab tuaj yeem hloov kho nyob rau hauv ntau qhov loj.
3. Observation studio
Cov duab hluav taws xob tau xav txog ntawm lub vijtsam fluorescent. Lub teeb fluorescent yog proportional rau electron beam tam sim no. Siv lub tshuab hluav taws xob qhuav siv lub tshuab fluorescent los thaij duab. Lub peev xwm photosensitive ntawm cov phaj qhuav yog cuam tshuam nrog nws cov wavelength.
4. Lub tshuab nqus tsev
Lub tshuab nqus tsev muaj lub tshuab nqus tsev twj, roj diffusion twj tso kua mis, ion twj tso kua mis, lub tshuab nqus tsev ntsuas ntsuas thiab lub tshuab nqus tsev raj. Nws txoj haujlwm yog tshem tawm cov pa roj hauv lub lens fwj, kom lub tshuab nqus tsev ntawm lub lens chim yuav tsum ncav cuag tsawg kawg yog 10-5 Torr, thiab lub tshuab nqus tsev zoo tshaj plaws tuaj yeem ncav cuag 10-9-10-10 Torr. Yog tias lub tshuab nqus tsev qis qis, kev sib tsoo ntawm electrons thiab roj molecules tuaj yeem ua rau tawg thiab cuam tshuam qhov sib txawv. Nws kuj tseem yuav ua rau muaj hluav taws xob ionization ntawm cov hluav taws xob hluav taws xob thiab cov anode, ua rau cov hluav taws xob sib cuam tshuam. Residual gases kuj tuaj yeem corrode cov filament thiab paug cov qauv.
5. Lub zog tswj qhov system
Lub instability ntawm accelerating voltage thiab lens magnetic tam sim no yuav ua rau loj chromatic aberration thiab txo cov kev daws teeb meem ntawm electron microscope. Yog li ntawd, kev ruaj ntseg ntawm accelerating voltage thiab lens tam sim no yog ib qho tseem ceeb los ntsuas qhov ua tau zoo ntawm electron microscope. TEM Circuit Court yog tsim los ntawm cov nram qab no: high voltage DC fais fab mov, lens excitation fais fab mov, deflection coil fais fab mov, electron phom filament cua sov fais fab mov, lub tshuab nqus tsev tswj Circuit Court, lub tshuab nqus tsev twj fais fab mov, lub koob yees duab tsav ntaus ntawv thiab tsis siv neeg kis. Circuit Court.
Tsis tas li ntawd, ntau qhov kev ua tau zoo electron microscopes tau nruab nrog cov khoom siv scanning, lub zog spectroscopy, electron zog poob spectroscopy.
