Electron MicroscopeOptical MicroscopeImaging PrinciplesSimilarities and Differences
Electron microscope yog ib qho cuab yeej siv hluav taws xob thiab hluav taws xob lens hloov lub teeb beam thiab optical lens raws li lub hauv paus ntsiab lus ntawm electron optics, thiaj li hais tias cov qauv zoo ntawm cov khoom yog imaged nyob rau hauv high magnification.
Qhov kev daws teeb meem ntawm lub tshuab ntsuas hluav taws xob tau qhia nyob rau hauv cov nqe lus ntawm qhov sib nrug me me ntawm ob lub ntsiab lus nyob sib ze uas nws tuaj yeem daws tau.Hauv xyoo 1970s, qhov kev daws teeb meem ntawm lub tshuab hluav taws xob xa hluav taws xob yog li ntawm 0.3 nanometers (qhov kev daws teeb meem ntawm tib neeg lub qhov muag yog li 0.1 millimeters). Niaj hnub no, qhov loj ntawm electron microscope yog ntau tshaj 3 lab lub sij hawm, thaum lub loj magnification ntawm optical microscope yog hais txog 2, 000 lub sij hawm, kom lub electron microscope yuav ncaj qha soj ntsuam lub atoms ntawm tej yam hnyav hlau thiab muaju ntawm cov atomic dots nyob rau hauv kev npaj ntawm cov array zoo.
Txawm hais tias qhov kev daws teeb meem ntawm lub tshuab ntsuas hluav taws xob tau ua tau zoo dua li lub tshuab hluav taws xob kho qhov muag, tab sis lub tshuab ntsuas hluav taws xob yuav tsum tau ua haujlwm hauv lub tshuab nqus tsev, yog li nws tsis yooj yim rau kev soj ntsuam cov kab mob uas muaj sia nyob, thiab irradiation ntawm cov kab hluav taws xob electron yuav ua rau cov qauv lom neeg los ntawm irradiation puas. Lwm yam teeb meem, xws li qhov ci ntsa iab ntawm rab phom electron thiab kev txhim kho qhov zoo ntawm lub lens electron kuj yuav tsum tau mus kawm ntxiv.
Lub zog daws teeb meem yog qhov ntsuas tseem ceeb ntawm lub tshuab ntsuas hluav taws xob, uas muaj feem xyuam nrog lub khob hliav qab ntawm qhov xwm txheej thiab wavelength ntawm cov kab hluav taws xob hla dhau ntawm cov qauv. Lub wavelength ntawm pom lub teeb yog hais txog {{0}} nm, thiab lub wavelength ntawm lub electron beam muaj feem xyuam rau lub accelerating voltage. Thaum qhov hluav taws xob nrawm yog 50 txog 100 kV, lub wavelength ntawm lub teeb hluav taws xob yog li 0.0053 txog 0.0037 nm. Vim hais tias lub wavelength ntawm lub electron beam yog ntau me dua lub wavelength ntawm pom lub teeb, yog li txawm tias lub khob hliav qab ntawm lub electron beam tsuas yog 1 feem pua ntawm cov optical microscope, lub zog daws teeb meem ntawm electron microscope yog tseem nyob deb tshaj qhov optical microscope.
Electron microscope muaj peb ntu: daim iav raj, lub tshuab nqus tsev thiab lub txee fais fab. Lub thoob feem ntau muaj phom electron, electron lens, coj mus kuaj, fluorescent screen thiab lub koob yees duab mechanism thiab lwm yam khoom, cov khoom no feem ntau sib sau los ntawm sab saum toj mus rau hauv qab rau hauv ib kem; Lub tshuab nqus tsev muaj lub tshuab nqus tsev twj tso kua mis, lub twj tso kua mis diffusion thiab lub tshuab nqus tsev vacuum, thiab lwm yam, thiab los ntawm cov raj xa dej txuas nrog lub thoob ntawm daim iav; fais fab mov txee muaj lub tshuab hluav taws xob high-voltage, excitation tam sim no stabilizer thiab ntau yam kev tswj hwm kev tswj hwm.
Electron lens yog ib qho tseem ceeb ntawm electron microscope chim, nws yog symmetrical rau lub axis ntawm lub chim ntawm qhov chaw hluav taws xob los yog magnetic teb thiaj li hais tias cov electron khiav mus rau lub axis ntawm lub tsim ntawm lub focusing lub luag hauj lwm ntawm lub iav convex lens. ua kom lub luag haujlwm ntawm lub teeb ntawm lub teeb tsom yog zoo ib yam li lub luag haujlwm ntawm lub lens, yog li nws yog hu ua electron lens. Niaj hnub nimno electron microscopes feem ntau siv electromagnetic lo ntsiab muag, uas tsom cov electrons los ntawm ib tug muaj zog magnetic teb generated los ntawm ib tug ruaj khov DC excitation tam sim no los ntawm ib tug coil nrog ib tug ncej khau.
Electron microscopes tuaj yeem muab faib ua kis tau tus mob electron microscopes, scanning electron microscopes, reflection electron microscopes thiab emission electron microscopes raws li lawv cov qauv thiab siv. Kev xa hluav taws xob tshuab hluav taws xob feem ntau yog siv los soj ntsuam cov neeg uas muaj lub tshuab microscopes tsis tuaj yeem paub qhov txawv ntawm cov qauv zoo ntawm cov khoom; scanning electron microscope feem ntau yog siv los soj ntsuam cov khoom nto morphology, tab sis kuj nrog X-ray diffractometer los yog electron spectrometer ua ke los ua tus electron microprobe, siv rau kev tsom xam ntawm cov khoom muaj pes tsawg leeg; emissive electron microscope yog siv rau kev kawm ntawm qhov chaw ntawm tus kheej-emission ntawm electrons.
