Transmission Electron Microscope Ua Haujlwm Txoj Cai thiab Kev Siv
Transmission Electron Microscope (TEM), tuaj yeem pom hauv lub tshuab ntsuas qhov muag tsis tuaj yeem pom tsawg dua {{{0}}}.2 um ntawm cov qauv zoo, cov qauv no hu ua sub-microscopic qauv lossis ultramicrostructure. Txhawm rau pom cov qauv no, nws yog ib qho tsim nyog los xaiv qhov luv luv wavelength ntawm lub teeb qhov chaw, txhawm rau txhim kho qhov kev daws teeb meem ntawm lub tshuab tsom. Xyoo 1932 Ruska tau tsim lub teeb hluav taws xob ua lub teeb ci ntawm kev xa hluav taws xob hluav taws xob, lub wavelength ntawm lub teeb hluav taws xob yog luv dua li lub wavelength ntawm pom lub teeb thiab ultraviolet lub teeb, thiab lub wavelength ntawm electron beam thiab emission ntawm electron beam. lub hauv paus square ntawm qhov voltage inversely proportional rau qhov yog hais tias qhov siab dua qhov voltage ntawm lub wavelength ntawm luv luv. Tam sim no qhov kev daws teeb meem ntawm TEM yog mus txog 0.2nm.
Kev xa hluav taws xob tshuab hluav taws xob ua haujlwm txoj hauv kev yog lub teeb hluav taws xob tawm los ntawm cov phom hluav taws xob, hauv lub tshuab nqus tsev raws li qhov kho qhov muag ntawm daim iav lub cev los ntawm daim iav condenser, los ntawm daim iav condenser yuav tau sib sau ua ke rau hauv lub teeb ntawm ntse, ci thiab zoo ib yam, irradiation ntawm cov qauv hauv cov qauv chamber ntawm cov qauv; los ntawm cov qauv tom qab lub beam ntawm electrons nqa cov qauv nrog cov ntaub ntawv nyob rau hauv cov qauv, cov qauv nyob rau hauv lub ntom los ntawm tus nqi ntawm electrons yog me me, tus nqi ntawm electrons kis tau los ntawm sparser qhov chaw ntau electrons; Tom qab lub convergence ntawm lub hom phiaj lens tsom thiab Tom qab lub hom phiaj lens convergence tsom thiab thawj magnification, lub electron beam mus rau hauv qis theem ntawm lub nruab nrab lens thiab thawj, thib ob projection daim iav rau integrated magnification imaging, thiab thaum kawg lub enlarged electronic duab projected rau chav soj ntsuam ntawm fluorescent screen board; fluorescent screen yuav hloov mus rau hauv cov duab pom ntawm cov duab hluav taws xob rau tus neeg siv saib. Hauv seem no, cov qauv tseem ceeb thiab cov ntsiab lus ntawm txhua qhov system tau piav qhia.
Lub hauv paus ntsiab lus duab ntawm kev xa hluav taws xob hluav taws xob tuaj yeem muab faib ua peb qhov xwm txheej:
1. Kev nqus zoo li: thaum lub tshuab hluav taws xob tua rau qhov loj, qhov ntom ntom ntawm cov qauv, cov nyhuv tseem ceeb ntawm cov txheej txheem yog cov nyhuv tawg. Cov qauv ntawm cov tuab tuab ntawm qhov chaw ntawm lub kaum sab xis ntawm lub tshuab hluav taws xob yog qhov loj, los ntawm cov hluav taws xob tsawg dua, zoo li qhov ci ntawm qhov tsaus ntuj. Thaum ntxov kis tau tus mob electron microscopes tau ua raws li txoj cai no.
2. Cov duab diffraction: Tom qab cov kab hluav taws xob diffracted los ntawm cov qauv, qhov amplitude faib ntawm diffraction nthwv dej ntawm qhov sib txawv ntawm cov qauv sib raug rau qhov sib txawv diffraction muaj peev xwm ntawm txhua feem ntawm cov siv lead ua hauv cov qauv. Thaum muaj cov khoom siv lead ua tsis xws luag, qhov muaj peev xwm ntawm qhov tsis xws luag yog qhov sib txawv ntawm qhov chaw tsis zoo, yog li ua rau lub amplitude faib ntawm diffraction yoj tsis sib xws thiab qhia txog kev faib tawm ntawm cov khoom siv lead ua tsis zoo.
3. Phase duab: Thaum cov qauv nyias nyias li 100Å lossis tsawg dua, cov khoom siv hluav taws xob tuaj yeem dhau los ntawm cov qauv, thiab qhov kev hloov pauv ntawm cov nthwv dej tuaj yeem tsis quav ntsej, thiab cov duab los ntawm cov theem hloov.
