X-rays muaj ntau yam khoom tshwj xeeb raws li hluav taws xob uas dhau mus dhau lawv qhov luv luv wavelength. Ib qho ntawm lawv cov khoom tseem ceeb rau kev tshawb fawb yog lub ntsiab lus xaiv. Los ntawm kev xaiv thiab tshuaj xyuas cov spectra ntawm tus kheej cov ntsiab lus uas nyob rau hauv qhov chaw tshwj xeeb hauv cov molecules complex, peb muaj ib qho chaw "atomic sensor". Los ntawm kev tshuaj xyuas cov atoms ntawm lub sijhawm sib txawv tom qab excitation ntawm cov qauv los ntawm lub teeb, peb tuaj yeem taug qab txoj kev loj hlob ntawm cov khoom siv hluav taws xob thiab cov qauv kev hloov pauv txawm tias nyob rau hauv cov txheej txheem nyuaj, lossis, hauv lwm lo lus, peb tuaj yeem ua raws li cov khoom siv hluav taws xob los ntawm cov molecule thiab los ntawm kev sib tshuam.
History
Tus neeg tsim hluav taws xob yog Wilhelm Conrad Röntgen. Muaj ib zaug, thaum ib tus kws tshawb fawb tau tshawb xyuas lub peev xwm ntawm ntau yam khoom siv los tiv thaiv rays, nws tau tso ib qho me me ntawm cov hlau lead hauv txoj hauj lwm thaum muaj qhov tso tawm. Yog liYog li, Roentgen pom thawj daim duab x-ray, nws tus kheej shimmering ghostly skeleton ntawm ib qho screen ntawm barium platinocyanide. Tom qab ntawd nws tau tshaj tawm tias nws yog lub sijhawm no nws tau txiav txim siab txuas ntxiv nws cov kev sim hauv kev zais cia vim nws ntshai tsam nws lub koob npe nrov yog tias nws qhov kev soj ntsuam tsis raug. Tus kws tshawb fawb German tau txais thawj Nobel nqi zog hauv Physics hauv 1901 rau kev tshawb pom X-rays hauv xyoo 1895. Raws li SLAC National Accelerator Laboratory, nws cov thev naus laus zis tshiab tau txais los ntawm lwm cov kws tshawb fawb thiab kws kho mob sai sai.
Charles Barkla, tus kws tshawb fawb Askiv Askiv, tau tshawb fawb ntawm xyoo 1906 thiab 1908 uas ua rau nws tshawb pom tias X-rays tuaj yeem yog tus yam ntxwv ntawm qee yam tshuaj. Nws txoj haujlwm kuj ua rau nws tau txais Nobel nqi zog hauv Physics, tab sis tsuas yog xyoo 1917.
Kev siv X-ray spectroscopy tau pib ua ntej me ntsis, xyoo 1912, pib nrog kev koom tes ntawm leej txiv thiab tus tub ntawm cov kws tshawb fawb Askiv, William Henry Bragg thiab William Lawrence Bragg. Lawv siv spectroscopy los kawm txog kev sib cuam tshuam ntawm X-rays nrog atoms hauv cov muaju. Lawv cov txheej txheem, hu ua X-ray crystallography, tau dhau los ua tus qauv hauv thaj chaw los ntawm xyoo tom ntej, thiab lawv tau txais Nobel nqi zog hauv Physics hauv xyoo 1915.
Kev ua haujlwm
Nyob rau xyoo tas los no, X-ray spectrometry tau siv ntau yam tshiab thiab zoo siab heev. Nyob rau saum npoo ntawm Mars muaj X-ray spectrometer uas saucov ntaub ntawv hais txog cov khoom uas tsim cov av. Lub zog ntawm cov kab teeb tau siv los kuaj xyuas cov xim txhuas ntawm cov khoom ua si, uas txo qhov kev pheej hmoo ntawm cov hlau lead lom. Kev sib koom tes ntawm kev tshawb fawb thiab kos duab tuaj yeem pom hauv kev siv hluav taws xob hluav taws xob thaum siv hauv tsev cia puav pheej los txheeb xyuas cov khoom uas tuaj yeem ua rau cov khoom puas tsuaj.
Cov ntsiab cai ua haujlwm
Thaum lub atom tsis ruaj khov lossis tawg los ntawm lub zog siab, nws cov electrons dhia ntawm qib zog. Raws li cov electrons kho, lub caij absorbs thiab emits high-zog X-ray photons nyob rau hauv ib tug yam ntxwv yam ntxwv ntawm lub atoms uas ua rau cov tshuaj lom. Nrog X-ray spectroscopy, kev hloov pauv ntawm lub zog tuaj yeem txiav txim siab. Qhov no tso cai rau koj txheeb xyuas cov khoom thiab pom kev cuam tshuam ntawm atoms hauv ntau qhov chaw.
Muaj ob txoj hauv kev tseem ceeb ntawm X-ray spectroscopy: wavelength dispersive (WDXS) thiab lub zog dispersive (EDXS). WDXS ntsuas ib lub wavelength X-rays uas yog diffracted ntawm ib tug siv lead ua. EDXS ntsuas X-rays tawm los ntawm electrons txhawb nqa los ntawm lub zog siab ntawm cov khoom siv hluav taws xob.
Kev tsom xam ntawm X-ray spectroscopy nyob rau hauv ob txoj kev ntawm kev faib hluav taws xob qhia cov qauv atomic ntawm cov khoom thiab, yog li ntawd, cov ntsiab lus hauv cov khoom txheeb xyuas.
Muaj ntau txoj hauv kev sib txawv ntawm X-ray thiab kho qhov muag spectroscopy ntawm hluav taws xob spectrum, uas yog siv rau ntau yam kev tshawb fawb thiab thev naus laus zis,suav nrog archaeology, astronomy thiab engineering. Cov txheej txheem no tuaj yeem siv los ntawm nws tus kheej lossis ua ke los tsim cov duab tiav ntawm cov khoom siv tshuaj ntsuam xyuas lossis khoom siv.
WDXS
X-ray photoelectron spectroscopy (WDXS) yog ib qho kev ntsuas qhov ntsuas qhov ntsuas qhov ntsuas ntawm qhov chaw uas ntsuas lub hauv paus muaj pes tsawg leeg hauv ntau qhov chaw ntawm qhov chaw ntawm cov khoom hauv qab kev kawm, thiab tseem txiav txim siab txog cov qauv ntawm cov qauv, tshuaj hauv lub xeev thiab hluav taws xob lub xeev ntawm cov khoom uas muaj nyob rau hauv cov khoom. Cias muab tso, WDXS yog ib txoj kev ntsuas muaj txiaj ntsig vim nws qhia tsis tau tsuas yog cov yam ntxwv hauv cov yeeb yaj kiab xwb, tab sis kuj muaj cov yam ntxwv dab tsi tau tsim tom qab ua tiav.
X-ray spectra yog tau los ntawm irradiating ib yam khoom nrog ib tug X-ray beam thaum ib txhij ntsuas lub kinetic zog thiab cov xov tooj ntawm electrons uas tshwm sim los ntawm sab sauv 0-10 nm ntawm cov khoom soj ntsuam. WDXS yuav tsum muaj lub tshuab nqus tsev siab (P ~ 10-8 millibars) lossis ultra-high nqus (UHV; P <10-9 millibars) tej yam kev mob. Txawm hais tias WDXS ntawm atmospheric siab yog tam sim no tab tom tsim, nyob rau hauv uas cov qauv raug soj ntsuam ntawm lub siab ntawm ob peb kaum millibars.
ESCA (X-ray Electron Spectroscopy for Chemical Analysis) yog ib lub ntsiab lus uas tau tsim los ntawm Kai Siegbahn pawg neeg tshawb fawb los hais txog cov tshuaj (tsis yog cov ntsiab lus) cov ntaub ntawv uas cov txheej txheem muab. Hauv kev xyaum, siv cov khoom siv hauv chav kuajX-rays, XPS pom txhua lub ntsiab lus nrog tus lej atomic (Z) ntawm 3 (lithium) thiab siab dua. Nws tsis tuaj yeem ntes tau hydrogen (Z=1) lossis helium (Z=2).
EDXS
Energy Dispersive X-Ray Spectroscopy (EDXS) yog cov txheej txheem tshuaj microanalysis siv ua ke nrog kev tshuaj ntsuam xyuas electron microscopy (SEM). EDXS txoj kev kuaj pom X-rays tawm los ntawm cov qauv thaum foob pob hluav taws xob los ua tus yam ntxwv ntawm cov khoom siv hluav taws xob ntawm cov khoom ntsuas. Cov ntsiab lus lossis theem me me li 1 µm tuaj yeem txheeb xyuas.
Thaum tus qauv raug foob nrog SEM electron beam, electrons raug rho tawm ntawm cov atoms uas ua rau saum npoo ntawm cov qauv. Cov txiaj ntsig electron voids tau ntim nrog cov hluav taws xob los ntawm lub xeev siab dua, thiab X-rays raug tso tawm kom sib npaug ntawm lub zog sib txawv ntawm lub xeev ntawm ob lub electrons. X-ray zog yog yam ntxwv ntawm lub caij uas nws tau tawm.
Lub EDXS x-ray detector ntsuas tus txheeb ze ntawm cov rays nyob ntawm lawv lub zog. Tus ntes feem ntau yog silicon drift lithium khoom lub xeev cov cuab yeej. Thaum ib qho xwm txheej X-ray beam tsoo lub ntes, nws tsim cov nqi mem tes uas yog proportional rau lub zog ntawm X-ray. Tus nqi mem tes yog hloov mus rau hauv qhov hluav taws xob mem tes (uas tseem muaj feem cuam tshuam rau lub zog X-ray) los ntawm kev siv lub preamplifier them nqi. Tom qab ntawd lub teeb liab raug xa mus rau multichannel analyzer qhov twg cov pulses tau txheeb los ntawm qhov hluav taws xob. Lub zog txiav txim siab los ntawm qhov ntsuas qhov ntsuas hluav taws xob rau txhua qhov xwm txheej X-ray raug xa mus rau lub khoos phis tawj kom pom thiab ntsuas cov ntaub ntawv ntxiv. X-ray lub zog spectrum piv rau suav yog kwv yees los txiav txim qhov muaj pes tsawg leeg ntawm cov qauv loj.
XRF
X-ray fluorescence spectroscopy (XRF) yog siv rau niaj hnub, tsis muaj kev puas tsuaj tshuaj lom neeg ntawm pob zeb, pob zeb, sediments thiab kua. Txawm li cas los xij, XRF feem ntau tsis tuaj yeem txheeb xyuas ntawm qhov chaw me me (2-5 microns), yog li nws feem ntau yog siv rau kev tshuaj xyuas ntau ntawm cov feem loj ntawm cov ntaub ntawv geological. Cov txheeb ze yooj yim thiab tus nqi qis ntawm cov qauv kev npaj, nrog rau kev ruaj ntseg thiab yooj yim ntawm kev siv X-ray spectrometers, ua rau txoj kev no yog ib qho ntawm feem ntau siv rau kev tsom xam ntawm cov kab tseem ceeb hauv pob zeb, cov zaub mov thiab sediments.
Lub physics ntawm XRF XRF nyob ntawm cov hauv paus ntsiab lus uas muaj ntau yam rau ntau lwm yam cuab yeej uas muaj kev cuam tshuam ntawm cov kab hluav taws xob thiab X-rays ntawm cov qauv, suav nrog cov txheej txheem hluav taws xob xws li SEM-EDS, diffraction (XRD), thiab wavelength. dispersive radiography (microprobe WDS).
Kev tsom xam ntawm cov kab tseem ceeb hauv cov ntaub ntawv geological los ntawm XRF yog ua tau vim yog tus cwj pwm ntawm atoms thaum lawv cuam tshuam nrog hluav taws xob. Thaum cov khoom sivTxaus siab los ntawm lub zog hluav taws xob luv luv-yoj hluav taws xob (xws li X-rays), lawv tuaj yeem ua ionized. Yog hais tias muaj hluav taws xob txaus rau dislodge lub kaw ntom nti nyob hauv electron, lub atom yuav tsis ruaj tsis khov thiab sab nrauv electron hloov lub sab hauv uas ploj lawm. Thaum qhov no tshwm sim, lub zog raug tso tawm vim qhov txo qis zog ntawm sab hauv electron orbital piv rau sab nrauv. Cov hluav taws xob muaj lub zog qis dua qhov xwm txheej thawj X-ray thiab hu ua fluorescent.
Lub XRF spectrometer ua haujlwm vim tias yog ib qho piv txwv yog illuminated nrog lub teeb hluav taws xob xoo hluav taws xob, lub npe hu ua teeb meem teeb meem, qee lub zog tau tawg, tab sis qee qhov kuj tau nqus hauv cov qauv, uas nyob ntawm nws cov tshuaj. muaj pes tsawg leeg.
XAS
X-ray absorption spectroscopy (XAS) yog qhov ntsuas ntawm kev hloov pauv hauv av hluav taws xob ntawm cov hlau mus rau cov hluav taws xob zoo siab (LUMO) thiab txuas ntxiv mus; tus qub yog hu ua X-ray Absorption Near Structure (XANES) thiab tom kawg li X-ray Extended Absorption Fine Structure (EXAFS), uas kawm txog cov qauv zoo ntawm kev nqus ntawm lub zog siab tshaj qhov hluav taws xob tso tawm. Ob txoj hauv kev no muab cov ntaub ntawv qhia ntxiv, XANES spectra qhia txog cov qauv hluav taws xob thiab kev sib luag ntawm qhov chaw hlau, thiab EXAFS qhia cov lej, hom thiab kev ncua deb rau ligands thiab cov atoms nyob sib ze los ntawm cov khoom nqus.
XAS tso cai rau peb los kawm cov qauv hauv zos ntawm ib qho kev txaus siab yam tsis muaj kev cuam tshuam los ntawm kev nqus los ntawm cov protein matrix, dej lossis cua. Txawm li cas los xij, X-ray spectroscopy ntawm metalloenzymes tau muaj kev sib tw vim qhov sib txheeb me me ntawm cov ntsiab lus txaus siab hauv cov qauv. Nyob rau hauv tas li ntawd, tus txheej txheem mus kom ze yog siv X-ray fluorescence los xyuas kom meej nqus spectrum es tsis txhob siv cov kis tau tus mob hom. Txoj kev loj hlob ntawm thib peb-tiam mob siab X-ray qhov chaw ntawm synchrotron hluav taws xob kuj ua rau nws muaj peev xwm mus kawm dilute cov qauv.
Hlau complexes, raws li cov qauv nrog cov qauv paub, yog qhov tseem ceeb rau kev nkag siab txog XAS ntawm metalloproteins. Cov complexes no muab lub hauv paus rau kev ntsuam xyuas qhov cuam tshuam ntawm kev sib koom ua ke nruab nrab (kev sib koom tes them nqi) ntawm lub zog nqus dej. Txoj kev kawm ntawm cov qauv tsim qauv zoo sib xws kuj tseem muab cov qauv ntsuas rau kev nkag siab EXAFS los ntawm cov tshuab hlau ntawm cov qauv tsis paub.
Qhov txiaj ntsig tseem ceeb ntawm XAS dhau ntawm X-ray crystallography yog cov ntaub ntawv hauv cheeb tsam ib puag ncig ntawm qhov kev txaus siab tuaj yeem tau txais txawm tias los ntawm cov qauv tsis zoo xws li hmoov thiab tshuaj. Txawm li cas los xij, cov qauv txiav txim xws li daim nyias nyias thiab ib qho crystals feem ntau nce cov ntaub ntawv tau los ntawm XAS. Rau oriented ib leeg muaju los yog daim nyias nyias, interatomic vector orientations tuaj yeem raug xam los ntawm kev ntsuas ntawm dichroism. Cov txheej txheem no tshwj xeeb tshaj yog muaj txiaj ntsig zoo rau kev txiav txim siab cov qauv hauv pawg.polynuclear hlau xws li Mn4Ca pawg txuam nrog oxidation ntawm dej hauv cov pa oxygen tso tawm photosynthetic complex. Ntxiv mus, qhov kev hloov me me hauv geometry / qauv cuam tshuam nrog kev hloov pauv ntawm cov xeev nruab nrab, hu ua S-states, hauv cov dej oxidation cov voj voog tuaj yeem tshawb pom tau yooj yim siv XAS.
Applications
X-ray spectroscopy cov tswv yim yog siv ntau yam kev tshawb fawb, suav nrog archaeology, anthropology, astronomy, chemistry, geology, engineering, thiab pej xeem noj qab haus huv. Nrog nws txoj kev pab, koj tuaj yeem tshawb pom cov ntaub ntawv zais ntawm cov khoom qub qub thiab cov seem. Piv txwv li, Lee Sharp, tus kws tshaj lij ntawm chemistry ntawm Grinnell College hauv Iowa, thiab cov npoj yaig siv XRF los taug qab lub hauv paus chiv keeb ntawm obsidian xub xub ua los ntawm cov neeg ua ntej keeb kwm hauv North American Southwest.
Astrophysicists, ua tsaug rau X-ray spectroscopy, yuav kawm ntxiv txog seb cov khoom hauv qhov chaw ua haujlwm li cas. Piv txwv li, cov kws tshawb fawb ntawm Washington University hauv St. Louis npaj saib X-rays los ntawm cov khoom cosmic xws li qhov dub kom paub ntau ntxiv txog lawv cov yam ntxwv. Ib pab neeg coj los ntawm Henryk Kravczynski, tus kws tshawb fawb thiab theoretical astrophysicist, npaj yuav tso ib qho X-ray spectrometer hu ua X-ray polarimeter. Pib txij lub Kaum Ob Hlis 2018, qhov ntsuas tau raug ncua hauv lub ntiaj teb huab cua nrog lub zais pa uas muaj helium rau lub sijhawm ntev.
Yuri Gogotsi, kws tshuaj thiab kws ua haujlwm,Drexel University of Pennsylvania tsim sputtered antennas thiab daim nyias nyias rau desalination los ntawm cov ntaub ntawv soj ntsuam los ntawm X-ray spectroscopy.
Cov kav hlau txais xov tsis pom pom tsuas yog ob peb kaum ntawm nanometers tuab, tab sis muaj peev xwm xa thiab xa xov tooj cua tsis tau. Cov txheej txheem XAS pab xyuas kom meej tias cov khoom sib xyaw ntawm cov khoom nyias nyias yog qhov tseeb thiab pab txiav txim siab conductivity. Gogotsi tau hais tias "Cov kav hlau txais xov yuav tsum muaj cov khoom siv hlau ua haujlwm tau zoo, yog li peb yuav tsum ua tib zoo saib xyuas cov khoom," Gogotsi hais.
Gogotzi thiab cov npoj yaig kuj tseem siv spectroscopy los tshuaj xyuas qhov chaw chemistry ntawm cov ntaub so ntswg uas desalinate dej los ntawm kev lim tawm cov ions tshwj xeeb xws li sodium.
Nyob hauv tshuaj
X-ray photoelectron spectroscopy pom daim ntawv thov hauv ntau qhov chaw ntawm kev tshawb fawb kho mob anatomical thiab hauv kev xyaum, piv txwv li, hauv cov tshuab CT niaj hnub no. Kev sau X-ray nqus spectra thaum lub sij hawm CT scan (siv photon suav lossis spectral scanner) tuaj yeem muab cov ncauj lus kom ntxaws ntxiv thiab txiav txim siab seb puas muaj dab tsi tshwm sim hauv lub cev, nrog cov tshuaj hluav taws xob qis dua thiab tsawg dua lossis tsis xav tau cov khoom sib txawv (dyes).
