Kev tsom xam thiab siv Electron Microscope hauv Nanomaterials
Raws li lub npe implies, lub microscope yog ib qho cuab yeej siv los nthuav cov khoom me me rau kev soj ntsuam. Los ntawm ib qho hluav taws xob kho qhov muag uas muaj peb lub tshuab hluav taws xob, lub teeb hluav taws xob tau tsom mus rau hauv lub teeb hluav taws xob me me txog li ob peb nm kom irradiate saum npoo ntawm daim ntawv xeem. Lub lens kawg yog nruab nrog lub tshuab scanning, uas feem ntau yog siv los tiv thaiv lub teeb hluav taws xob, kom nws tuaj yeem luam theej duab ob sab ntawm qhov chaw kuaj, thiab lub tshuab luam ntawv no tau synchronized nrog kev luam theej duab ntawm cathode ray (CRT) . Thaum lub teeb hluav taws xob hits Secondary electrons (secondary electrons) thiab reflected electrons zoo siab heev thaum kuaj daim ntawv xeem. Thaum cov electrons raug kuaj pom los ntawm lub tshuab ntes, lub teeb liab raug xa mus rau CRT los ntawm lub amplifier. Txij li thaum tam sim no ntawm lub scanning kauj yog synchronized nrog lub tam sim no ntawm daim duab raj, lub teeb liab generated ntawm ib tug taw tes rau ntawm qhov chaw ntawm lub xeem daim ntawv sib raug rau cov duab raj. Yog li ntawd, daim ntawv xeem Nws yog ib qho kev ntsuas ntsuas uas tuaj yeem qhia qhov topography thiab cov yam ntxwv ntawm qhov chaw ib los ntawm ib qho los ntawm kev siv cov duab synchronous. Electron microscopes tau muab faib ua ntau hom, thiab kev xaiv tsim nyog yog ua raws li qhov xav tau. Cov duab daws teeb meem lossis kev nthuav dav uas tsim los ntawm cov tshuab siv hluav taws xob sib txawv kuj txawv, xws li: SEM scanning electron microscope, TEM kis tau tus mob electron microscope, STM scanning Transmission electron microscope, AFM atomic force microscope, thiab lwm yam.
Cov khoom siv ntawm cov khoom xeem kuj yog ib qho tseem ceeb heev, feem ntau txiav txim siab los ntawm peb yam: kev sib xyaw ua ke thiab kev sib txuas, txhawm rau soj ntsuam cov nplai me me, thiab tom qab ntawd tsim lub tshuab hluav taws xob, cov cuab yeej no tsuas yog siv rau saum npoo ntawm cov khoom siv. , thiab tsis tuaj yeem muab cov ntaub ntawv sab hauv ntawm cov khoom siv. Cov ntaub ntawv muaj pes tsawg leeg thiab cov ntaub ntawv sib txuas, tab sis cov kws tshawb fawb cov ntaub ntawv yuav tsum paub txog cov qauv tsim thiab cov ntaub ntawv sib txuas hauv cov khoom, yog li TEM kis tau tus mob electron microscope muaj cov hluav taws xob hluav taws xob siab (100kM ~ 1MeV) los tsav cov kab hluav taws xob mus rau hauv xeem daim, los ntawm Tom qab cov qauv, vim hais tias ntawm lub Coulomb muaj peev xwm muaj zog sib cuam tshuam ntawm cov electrons thiab cov atoms nyob rau hauv cov qauv, tsis muaj poob ntawm lub zog, uas yog feem ntau hu ua "elastic scattering" phenomenon. Peb tuaj yeem tau txais cov ntaub ntawv hais txog lub microstructure sab hauv thiab cov qauv atomic los ntawm elastic thiab inelastic scattering electrons. Elastically tawg thiab inelastically tawg electrons yuav raug muab tso rau ntawm daim duab dav hlau los ntawm lub hom phiaj lens. Cov khoom siv hluav taws xob hluav taws xob nrog lub zog sib txawv yuav cuam tshuam rau qhov ntim ntawm cov khoom kuaj, thiab kev sib raug zoo yog proportional. Thaum qhov hluav taws xob siab, qee qhov hluav taws xob thib ob los ntawm qis dua 0.2 μm los ntawm qhov chaw (qhov tuab ntawm daim ntawv mica). Yog li ntawd, nws yog ib qho tsim nyog yuav tsum siv qhov hluav taws xob qis dua los saib xyuas cov khoom siv polymer xws li nanometer, kom tsis txhob poob cov ntaub ntawv ntawm qhov chaw sab saud, tab sis ua tib zoo saib xyuas cov nyhuv tawm ntawm cov khoom tsis zoo.
Kev cuam tshuam ntawm qhov chaw ntawm daim ntawv xeem ntawm EDS, yog tias SEM xeem daim ntawv nws tus kheej yog hlau lossis muaj cov conductivity zoo, nws tuaj yeem kuaj pom ncaj qha yam tsis muaj kev kho mob ua ntej. Txawm li cas los xij, yog tias nws tsis yog tus coj, nws yuav tsum tau coated nrog cov yeeb yaj kiab hlau nrog lub thickness ntawm 50-200Å ntawm qhov chaw. Cov yeeb yaj kiab hlau yuav tsum tau muab sib npaug rau ntawm qhov chaw kom tsis txhob cuam tshuam qhov chaw ntawm daim ntawv xeem. Cov yeeb yaj kiab hlau feem ntau yog kub lossis Au. - Pd alloy lossis platinum. Kev siv ntau tshaj plaws ntawm cov khoom npaj ua haujlwm muaj xws li: txiav, tu, kos, sib tsoo, polishing, yaig, hmoov txheej, kub plating, thiab lwm yam. Cov ntawv xeem loj yuav tsum tau txiav rau hauv qhov ntau thiab tsawg rau kev soj ntsuam, thaum cov ntawv xeem me me yuav tsum tau ua. embedded rau kev soj ntsuam. Qee lub hauv paus ntsiab lus yuav tsum tau them nyiaj mloog rau hauv kev npaj ntawm SEM xeem daim: txoj hauj lwm yuav tsum tau soj ntsuam yuav tsum tau qhia, cov conductivity ntawm lub nto yuav tsum zoo, tshav kub-resistant, kua los yog gel-zoo li tshuaj yuav tsum muaj kom tsis txhob volatilization, Qhov chaw uas tsis yog-conductive yuav tsum tau plated nrog kub, vim tias peb tsis tuaj yeem txiav txim siab cov khoom siv Lub hauv paus, qhov kev faib ua feem ntawm cov teeb liab tsim los ntawm cov hluav taws xob backscattered, yog soj ntsuam zoo thiab ntau los ntawm kev txheeb xyuas cov yam ntxwv tso tawm los ntawm daim ntawv xeem.
Lwm lub tshuab ntsuas hluav taws xob, TEM, tuaj yeem tsis tsuas yog saib xyuas cov qauv dislocation hauv cov siv lead ua thiab tom qab kev kho thiab kev kho cua sov, tab sis kuj ncaj qha saib xyuas qhov tsim ntawm cov muaju thib ob, kaum sab xis, recrystallization, nkag mus, thiab dislocation hauv cov muaju ntau. Muaj ntau qhov tshwm sim uas muaj feem xyuam nrog cov khoom siv hluav taws xob, xws li kev sib cuam tshuam nrog cov nag lossis daus, lub teeb hluav taws xob cuam tshuam nrog cov khoom kuaj, tsim cov qauv diffraction ntawm lub dav hlau backfocal tom qab lub hom phiaj lens, thiab tsim cov duab loj ntawm cov duab. dav hlau. . Thaum ua haujlwm ntawm lub tshuab ntsuas hluav taws xob, daim iav nruab nrab feem ntau yog tsom rau ntawm lub dav hlau focal lossis lub dav hlau pom tom qab lub hom phiaj lens los ntawm kev hloov pauv tam sim no ntawm daim iav nruab nrab, thiab tom qab ntawd cov qauv diffraction lossis cov duab loj yog pom raws li. Ob daim duab tsim los ntawm qhov sib txawv ntawm qhov sib txawv ntawm qhov sib txawv ntawm cov khoom kuaj irradiated los ntawm cov kab hluav taws xob yog cov duab ci teb thiab cov duab tsaus ntuj. Qhov txawv ntawm lawv yog hais tias lub aperture ntawm lub hom phiaj lens thaiv lub Electron beam (los yog direct electron beam), tsuas yog cia lub ncaj electron beam dhau los ntawm imaging (diffraction electron beam), saib thiab yees duab peb-dimensional qauv los yog hlais ntawm lub nto ntawm daim ntawv xeem, tshwj xeeb tshaj yog tsim nyog rau kev tshawb fawb ntawm cov qauv lom, tab sis nrog electron Shoots los ntawm cov khoom, nthuav tawm lawv lub xeev sab hauv. TEM tuaj yeem txheeb xyuas cov yam ntxwv me me li 1 Å, yog tias cov qauv yuav tsum tau txiav nrog lub thickness tsis tshaj 1000 Å. Yog li ntawd, TEM tsis tuaj yeem nthuav tawm cov duab loj ntawm yoov tshaj cum, tab sis nws tuaj yeem nthuav tawm tus kab mob zais hauv kab kab.
