Kev nce qib hauv kev siv tshuab ultraviolet teeb pom kev zoo

Kev nce qib hauv kev siv ultraviolet heevthev naus laus zis ntawm lub teeb

Nyob rau xyoo tas los no, cov khoom siv harmonic siab heev ultraviolet tau nyiam ntau tus neeg saib xyuas hauv thaj chaw ntawm electron dynamics vim lawv qhov kev sib raug zoo, lub sijhawm luv luv thiab lub zog photon siab, thiab tau siv rau hauv ntau yam kev tshawb fawb spectral thiab imaging. Nrog rau kev nce qib ntawm thev naus laus zis, qhov nolub teeb citab tom tsim kom muaj qhov rov ua dua zaus ntau dua, photon flux ntau dua, photon zog ntau dua thiab qhov dav ntawm lub zog luv dua. Qhov kev nce qib no tsis yog tsuas yog ua kom zoo dua qhov kev ntsuas ntawm cov teeb pom kev ultraviolet hnyav xwb, tab sis kuj muab cov hauv kev tshiab rau kev txhim kho thev naus laus zis yav tom ntej. Yog li ntawd, kev kawm tob thiab kev nkag siab txog qhov rov ua dua zaus ntau ultraviolet hnyav yog qhov tseem ceeb heev rau kev paub thiab kev siv thev naus laus zis tshiab.

Rau kev ntsuas electron spectroscopy ntawm femtosecond thiab attosecond lub sijhawm teev, tus naj npawb ntawm cov xwm txheej ntsuas hauv ib lub teeb feem ntau tsis txaus, ua rau cov teeb pom kev zoo qis qis tsis txaus kom tau txais cov ntaub ntawv txhim khu kev qha. Tib lub sijhawm, lub teeb pom kev zoo nrog cov photon flux qis yuav txo qhov sib piv ntawm cov teeb liab-rau-suab nrov ntawm cov duab microscopic thaum lub sijhawm raug txwv. Los ntawm kev tshawb nrhiav thiab kev sim tas mus li, cov kws tshawb fawb tau ua ntau yam kev txhim kho hauv kev tsim khoom thiab kev tsim qauv kis ntawm lub teeb ultraviolet siab rov ua dua. Cov thev naus laus zis siab heev ua ke nrog lub teeb ultraviolet siab rov ua dua tau siv los ua tiav qhov kev ntsuas siab ntawm cov qauv khoom siv thiab cov txheej txheem hluav taws xob dynamic.

Kev siv cov teeb pom kev zoo ultraviolet heev, xws li kev ntsuas angular resolved electron spectroscopy (ARPES), xav tau lub teeb ultraviolet heev kom ci ntsa iab rau cov qauv. Cov electrons ntawm qhov chaw ntawm cov qauv raug txhawb kom mus rau lub xeev tas mus li los ntawm lub teeb ultraviolet heev, thiab lub zog kinetic thiab lub kaum sab xis ntawm cov photoelectrons muaj cov ntaub ntawv qauv ntawm cov qauv. Lub electron analyzer nrog lub kaum sab xis daws teeb meem tau txais cov photoelectrons radiated thiab tau txais cov qauv band ze ntawm lub valence band ntawm cov qauv. Rau qhov rov ua dua zaus qis ultraviolet heev lub teeb pom kev zoo, vim tias nws ib lub pulse muaj ntau tus photons, nws yuav txhawb nqa ntau tus photoelectrons ntawm qhov chaw ntawm cov qauv hauv lub sijhawm luv luv, thiab Coulomb kev sib cuam tshuam yuav ua rau muaj kev nthuav dav ntawm kev faib tawm ntawm photoelectron kinetic zog, uas hu ua qhov chaw them nyiaj. Yuav kom txo qhov cuam tshuam ntawm qhov chaw them nyiaj, nws yog qhov tsim nyog los txo cov photoelectrons uas muaj nyob hauv txhua lub pulse thaum tswj hwm qhov photon flux tas mus li, yog li nws yog qhov tsim nyog los tsav lublasernrog rau qhov rov ua dua zaus siab los tsim cov teeb pom kev ultraviolet heev nrog qhov rov ua dua zaus siab.

Resonance enhanced cavity technology ua rau muaj kev sib haum xeeb siab ntawm MHz repetition frequency
Yuav kom tau txais lub teeb ci ultraviolet uas muaj qhov rov ua dua txog li 60 MHz, pab pawg Jones ntawm University of British Columbia hauv tebchaws United Kingdom tau ua qhov kev tsim hluav taws xob siab hauv lub qhov femtosecond resonance enhancement cavity (fsEC) kom ua tiav qhov chaw teeb ci ultraviolet uas siv tau zoo thiab siv rau kev sim electron spectroscopy (Tr-ARPES) uas daws tau lub sijhawm. Lub teeb ci muaj peev xwm xa cov photon flux ntau dua 1011 tus lej photon ib ob nrog ib qho harmonic ntawm qhov rov ua dua ntawm 60 MHz hauv qhov ntau ntawm lub zog ntawm 8 txog 40 eV. Lawv siv lub tshuab fiber laser ytterbium-doped ua lub hauv paus rau fsEC, thiab tswj cov yam ntxwv ntawm lub zog los ntawm kev tsim lub tshuab laser kom txo qis lub suab nrov ntawm lub hnab ntawv nqa khoom (fCEO) thiab tswj cov yam ntxwv ntawm lub zog zoo thaum kawg ntawm cov saw hlau amplifier. Yuav kom ua tiav qhov kev txhim kho resonance ruaj khov hauv fsEC, lawv siv peb lub voj voog servo rau kev tswj hwm rov qab, ua rau muaj kev ruaj khov ntawm ob qib kev ywj pheej: lub sijhawm ncig mus los ntawm lub voj voog pulse hauv fsEC phim lub sijhawm laser pulse, thiab qhov hloov pauv theem ntawm lub zog hluav taws xob nrog rau lub hnab ntawv pulse (piv txwv li, theem hnab ntawv carrier, ϕCEO).

Los ntawm kev siv roj krypton ua cov roj ua haujlwm, pab pawg tshawb fawb tau ua tiav kev tsim cov harmonics siab dua hauv fsEC. Lawv tau ua qhov kev ntsuas Tr-ARPES ntawm graphite thiab tau pom kev ua kom sov sai thiab tom qab ntawd qeeb qeeb ntawm cov pej xeem electron uas tsis muaj cua sov, nrog rau cov dynamics ntawm cov xeev tsis muaj cua sov ncaj qha ze ntawm Fermi theem saum toj no 0.6 eV. Lub teeb ci no muab cov cuab yeej tseem ceeb rau kev kawm txog cov qauv hluav taws xob ntawm cov ntaub ntawv nyuaj. Txawm li cas los xij, kev tsim cov harmonics siab hauv fsEC muaj cov kev xav tau siab heev rau kev cuam tshuam, kev them nyiaj rau kev sib kis, kev kho kom zoo ntawm qhov ntev ntawm qhov thiab kev xauv synchronization, uas yuav cuam tshuam loj heev rau kev txhim kho ntau yam ntawm qhov resonance-enhanced qhov. Tib lub sijhawm, qhov kev teb tsis sib xws ntawm cov plasma ntawm qhov chaw tseem ceeb ntawm qhov chaw kuj yog qhov nyuaj. Yog li ntawd, tam sim no, hom teeb ci no tsis tau dhau los ua lub teeb ultraviolet loj heev.lub teeb ci ntsa iab siab.