Hom Electron Microscopes
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 kev siv.
Kev xa hluav taws xob tshuab hluav taws xob feem ntau siv los saib xyuas cov khoom siv zoo uas tsis tuaj yeem daws tau los ntawm cov tshuab microscopes;
Scanning electron microscopes yog siv los soj ntsuam cov morphology ntawm cov khoom siv, thiab tseem tuaj yeem ua ke nrog X-ray diffractometers lossis electron zog spectrometers los tsim cov khoom siv hluav taws xob microprobes rau kev tsom xam cov khoom muaj pes tsawg leeg;
Emission electron microscopy yog siv rau kev kawm ntawm tus kheej-emitting electron nto.
(1) Transmission electron microscope
Cheebtsam ntawm kis tau tus mob electron microscope (TEM) muaj xws li:
1. Electron phom: emits electrons, muaj li ntawm cathode, kab sib chaws thiab anode.
2. Condenser lens: Nws yog lub lens hluav taws xob, uas ua rau lub teeb hluav taws xob muaj zog thiab tuaj yeem siv los tswj lub teeb pom kev zoo thiab lub kaum sab xis.
3. Sample chamber: muab cov qauv coj los soj ntsuam, thiab nruab nrog lub rooj sib hloov los hloov lub kaum sab xis ntawm cov qauv, nrog rau nruab nrog cua sov, cua txias thiab lwm yam khoom siv.
4. Lub Hom Phiaj Lens: Nws yog lub lens luv luv nrog kev nthuav dav siab, thiab nws txoj haujlwm yog ua kom pom cov duab hluav taws xob. Lub hom phiaj lo ntsiab muag yog tus yuam sij los txiav txim siab qhov kev daws teeb meem thiab kev pom zoo ntawm kev xa hluav taws xob tshuab hluav taws xob.
5. Daim iav nruab nrab: Nws yog lub lens tsis muaj zog nrog qhov sib txawv ntawm qhov loj, thiab nws txoj haujlwm yog rov ua kom pom cov duab hluav taws xob. Los ntawm kev kho qhov tam sim no ntawm daim iav nruab nrab, cov duab lossis electron diffraction qauv ntawm cov khoom tuaj yeem raug xaiv rau amplification.
6. Daim iav kis tau tus mob: Nws yog lub teeb pom kev zoo muaj zog, uas yog siv los ua kom loj dua cov duab nruab nrab tom qab qhov kev nthuav dav thib ob thiab tom qab ntawd tsim cov duab ntawm lub vijtsam fluorescent.
7. Secondary lub tshuab nqus tsev twj: nqus cov qauv chamber.
8. Lub koob yees duab ntaus ntawv: siv los sau cov duab. Vim tias cov khoom siv hluav taws xob tau yooj yim tawg los yog nqus tau los ntawm cov khoom, lub zog nkag mus rau qhov tsawg, thiab qhov ntom thiab tuab ntawm cov qauv yuav cuam tshuam rau qhov kawg imaging zoo. Thinner ultrathin seem yuav tsum tau npaj, feem ntau yog 50-100 nm.
Yog li ntawd, cov qauv yuav tsum tau ua tiav heev nyias thaum pom nrog ib tug kis tau tus mob electron microscope. Feem ntau npaj los ntawm nyias seem los yog khov etching:
(1) Cov txheej txheem nyias nyias
Cov qauv feem ntau yog kho nrog osmic acid thiab glutaraldehyde, embedded nrog epoxy resin, thiab hlais los ntawm thermal expansion lossis kauv propulsion. Lub thickness yog 20-50 nm, thiab stained nrog hnyav hlau ntsev kom nce qhov sib piv.
(2) Freeze etching method kuj hu ua freeze fracture method
Tom qab cov qauv tau khov rau hauv cov dej khov qhuav ntawm -100 degree lossis kua nitrogen ntawm -196 degree, cov qauv raug txiav sai sai nrog rab riam txias. Tom qab cov khoom tawg tau ua kom sov, cov dej khov sublimates tam sim ntawd hauv lub tshuab nqus tsev, nthuav tawm cov qauv tawg, uas yog hu ua etching. Tom qab etching tiav, ib txheej ntawm vaporized platinum yog txau ntawm 45o lub kaum sab xis mus rau ntu, thiab txheej txheej ntawm carbon yog txau ntawm 90o lub kaum sab xis txhawm rau txhim kho qhov sib piv thiab lub zog. Cov qauv yog tom qab ntawd zom nrog cov tshuaj sodium hypochlorite, thiab cov pa roj carbon thiab platinum zaj duab xis raug tshem tawm, uas yog hu ua zaj duab xis complex, uas tuaj yeem nthuav tawm cov morphology ntawm etched nto ntawm cov qauv. Cov duab tau txais nyob rau hauv lub tshuab ntsuas hluav taws xob sawv cev rau cov qauv ntawm qhov tawg ntawm lub xov tooj ntawm tes hauv cov qauv.
(2) Scanning electron microscope
Scanning electron microscope (SEM) tuaj tawm xyoo 1960, thiab qhov kev daws teeb meem tuaj yeem ncav cuag 6-10 nm tam sim no.
Nws txoj hauv kev ua haujlwm yog tias lub teeb pom kev zoo ntawm lub teeb hluav taws xob tawm los ntawm rab phom electron tsoo tus qauv los ntawm ob-theem condenser lens, deflection coil thiab lub hom phiaj lens, scans qhov saum npoo ntawm cov qauv thiab excites lwm electrons. Tus nqi ntawm cov khoom siv hluav taws xob thib ob tsim muaj feem cuam tshuam nrog lub kaum sab xis ntawm cov hluav taws xob hluav taws xob, uas yog, muaj feem xyuam rau cov qauv saum npoo ntawm cov qauv. Tom qab cov electrons thib ob tau sau los ntawm tus ntes, lawv tau hloov mus rau hauv cov teeb liab kho qhov muag los ntawm lub tshuab hluav taws xob, thiab tom qab ntawd hloov mus rau hauv cov teeb liab hluav taws xob los ntawm lub raj photomultiplier thiab amplifier los tswj qhov siv hluav taws xob hluav taws xob ntawm lub vijtsam fluorescent, thiab tso saib cov duab scanning. synchronized nrog electron beam. Cov duab yog ib daim duab peb-dimensional, xav txog cov qauv saum npoo ntawm cov qauv.
Ua ntej kev tshuaj ntsuam xyuas, cov qauv ntawm lub tshuab ntsuas hluav taws xob yuav tsum tau kho, lub cev qhuav dej, thiab tom qab ntawd txau nrog txheej txheej ntawm cov hlau hnyav. Cov hlau hnyav tshaj tawm cov teeb liab hluav taws xob theem nrab hauv qab lub foob pob hluav taws xob ntawm lub teeb hluav taws xob.
