Advances nyob rau hauv heev ultravioletlub teeb ci technology
Nyob rau hauv xyoo tsis ntev los no, huab ultraviolet siab harmonic qhov chaw tau nyiam dav nyob rau hauv lub teb ntawm electron dynamics vim lawv muaj zog coherence, luv luv mem tes ntev thiab siab photon zog, thiab tau siv nyob rau hauv ntau yam spectral thiab imaging kev tshawb fawb. Nrog kev nce qib ntawm technology, qhov noqhov kajyog tsim los ntawm ntau dua repetition zaus, ntau dua photon flux, ntau dua photon zog thiab luv luv mem tes dav. Qhov kev ua ntej no tsis yog tsuas yog ua kom zoo dua qhov kev ntsuas kev daws teeb meem ntawm qhov chaw teeb pom kev ultraviolet, tab sis kuj muab cov peev txheej tshiab rau kev txhim kho thev naus laus zis yav tom ntej. Yog li ntawd, qhov kev tshawb fawb tob tob thiab nkag siab txog kev rov ua dua ntau zaus huab cua ultraviolet lub teeb yog qhov tseem ceeb rau kev paub thiab siv cov cuab yeej siv thev naus laus zis.
Rau kev ntsuas electron spectroscopy ntawm femtosecond thiab attosecond time scales, tus naj npawb ntawm cov xwm txheej ntsuas nyob rau hauv ib lub beam feem ntau tsis txaus, ua rau tsawg zaus lub teeb qhov chaw tsis txaus kom tau txais cov txheeb cais txhim khu kev qha. Nyob rau tib lub sijhawm, lub teeb pom kev zoo nrog cov photon flux tsawg yuav txo cov teeb liab-rau-suab nrov piv ntawm microscopic duab thaum lub sij hawm raug txwv. Los ntawm kev tshawb nrhiav thiab kev sim tsis tu ncua, cov kws tshawb fawb tau ua ntau yam kev txhim kho hauv kev ua kom zoo tshaj plaws thiab kev sib kis tau zoo ntawm kev rov ua dua ntau zaus ultraviolet lub teeb. Cov cuab yeej siv thev naus laus zis siab tshaj plaws ua ke nrog kev rov ua dua siab zaus huab ultraviolet lub teeb qhov chaw tau siv los ua kom tiav qhov kev ntsuas siab ntawm cov khoom siv thiab cov txheej txheem hluav taws xob dynamic.
Daim ntawv thov ntawm cov teeb pom kev zoo ultraviolet, xws li angular daws teeb meem electron spectroscopy (ARPES), xav tau ib lub teeb ntawm ultraviolet teeb pom kev zoo rau cov qauv. Cov electrons nyob rau saum npoo ntawm cov qauv zoo siab rau lub xeev tas mus li los ntawm lub teeb ultraviolet, thiab lub zog kinetic thiab emission Angle ntawm photoelectrons muaj cov ntaub ntawv ntawm cov qauv band ntawm cov qauv. Lub electron analyzer nrog lub kaum sab xis daws teeb meem muaj nuj nqi tau txais cov hluav taws xob photoelectrons thiab tau txais cov qauv band nyob ze ntawm valence band ntawm cov qauv. Rau qhov tsawg zaus rov ua dua lub teeb ci ultraviolet, vim tias nws ib leeg pulse muaj ntau cov photons, nws yuav ua rau muaj ntau cov photoelectrons ntawm cov qauv hauv lub sijhawm luv luv, thiab Coulomb kev sib cuam tshuam yuav ua rau muaj kev nthuav dav loj ntawm kev faib khoom. ntawm photoelectron kinetic zog, uas yog hu ua qhov chaw them nqi nyhuv. Txhawm rau txo qhov cuam tshuam ntawm qhov chaw them nqi, nws yog ib qho tsim nyog yuav tsum tau txo cov photoelectrons uas muaj nyob rau hauv txhua tus mem tes thaum tswj cov photon flux tas li, yog li nws yog ib qho tsim nyog yuav tsum tau tsav lub tshuab hluav taws xob.lasernrog high repetition zaus los tsim cov huab ultraviolet lub teeb qhov chaw nrog siab repetition zaus.
Resonance enhanced kab noj hniav technology paub lub cim ntawm kev txiav txim siab harmonics ntawm MHz repetition zaus
Txhawm rau kom tau txais lub teeb pom kev zoo ultraviolet nrog qhov rov ua dua ntawm 60 MHz, Jones pab pawg ntawm University of British Columbia hauv tebchaws United Kingdom tau ua kom muaj kev sib haum xeeb siab nyob rau hauv femtosecond resonance li kab noj hniav (fsEC) kom ua tiav cov tswv yim. ultraviolet teeb pom kev zoo thiab siv nws mus rau lub sij hawm daws teeb meem angular daws electron spectroscopy (Tr-ARPES) thwmsim. Lub teeb qhov chaw muaj peev xwm xa cov photon flux ntawm ntau tshaj 1011 photon tus lej ib ob nrog ib qho kev sib haum xeeb ntawm qhov rov ua dua ntawm 60 MHz hauv lub zog ntawm 8 txog 40 eV. Lawv tau siv ytterbium-doped fiber ntau laser system ua cov noob rau fsEC, thiab tswj cov cwj pwm ntawm cov mem tes los ntawm kev tsim kho laser system kom txo qis lub hnab ntawv nqa khoom offset zaus (fCEO) suab nrov thiab tswj cov mem tes zoo compression yam ntxwv ntawm qhov kawg ntawm amplifier saw. Txhawm rau ua kom muaj kev ruaj khov resonance li hauv fsEC, lawv siv peb lub servo tswj loops rau kev tawm tswv yim tswj, ua rau muaj kev ruaj khov ntawm ob qib kev ywj pheej: lub sij hawm mus ncig ntawm lub plawv dhia hauv lub fsEC cuam tshuam lub sijhawm laser mem tes, thiab theem hloov. ntawm lub tshuab nqa hluav taws xob nrog rau lub hnab ntawv mem tes (ie, lub hnab ntawv nqa khoom theem, ϕCEO).
Los ntawm kev siv cov roj krypton ua cov roj ua haujlwm, pab pawg tshawb fawb tau ua tiav cov tiam ntawm kev txiav txim siab dua hauv fsEC. Lawv tau ua Tr-ARPES kev ntsuas ntawm graphite thiab pom cov thermal sai sai thiab tom qab qeeb recombination ntawm cov tsis-thermally zoo siab electron pejxeem, nrog rau cov dynamics ntawm non-thermally ncaj qha zoo siab xeev nyob ze Fermi qib siab tshaj 0.6 eV. Lub teeb ci no muab cov cuab yeej tseem ceeb rau kev kawm cov qauv hluav taws xob ntawm cov ntaub ntawv nyuaj. Txawm li cas los xij, tiam ntawm kev txiav txim siab sib haum xeeb hauv fsEC muaj qhov xav tau siab heev rau kev cuam tshuam, kev them nyiaj dispersion, kev kho kom zoo ntawm kab noj hniav ntev thiab synchronization xauv, uas yuav cuam tshuam rau kev txhim kho ntau yam ntawm cov kab noj hniav resonance. Nyob rau tib lub sijhawm, cov lus teb tsis yog theem ntawm plasma ntawm qhov chaw focal ntawm kab noj hniav kuj yog ib qho kev sib tw. Yog li ntawd, tam sim no, hom teeb pom kev zoo no tsis tau dhau los ua qhov tseem ceeb ntawm ultravioletsiab harmonic teeb qhov chaw.
Lub sij hawm xa tuaj: Plaub Hlis-29-2024