Inkqubela phambili kwi-ultraviolet ephezuluiteknoloji yomthombo wokukhanya
Kwiminyaka yakutshanje, imithombo ye-harmonic ephezulu ye-ultraviolet ephezulu itsale ingqalelo enkulu kwicandelo le-electron dynamics ngenxa yokuhambelana kwayo okunamandla, ubude be-pulse obufutshane kunye namandla aphezulu e-photon, kwaye isetyenzisiwe kwizifundo ezahlukeneyo ze-spectral kunye nemifanekiso. Ngokuhambela phambili kwetekhnoloji, okuumthombo wokukhanyaiphuhlisa isiya kwi-repeat frequency ephezulu, i-photon flux ephezulu, amandla aphezulu e-photon kunye nobubanzi obufutshane be-pulse. Le nkqubela phambili ayigcini nje ngokuphucula isisombululo sokulinganisa imithombo yokukhanya kwe-ultraviolet egqithisileyo, kodwa ikwabonelela ngamathuba amatsha ophuhliso lwetekhnoloji yexesha elizayo. Ke ngoko, uphando olunzulu kunye nokuqonda umthombo wokukhanya kwe-ultraviolet ephindaphindayo egqithisileyo kubaluleke kakhulu ekuqondeni nasekusebenziseni itekhnoloji yanamhlanje.
Kwimilinganiselo ye-electron spectroscopy kwizikali zexesha le-femtosecond kunye ne-attosecond, inani leziganeko ezilinganiswe kwi-beam enye lidla ngokwanelisa, nto leyo eyenza imithombo yokukhanya ephindaphindwayo ephantsi inganeli ukufumana izibalo ezithembekileyo. Kwangaxeshanye, umthombo wokukhanya one-photon flux ephantsi uya kunciphisa umlinganiselo wesignali-kwingxolo yemifanekiso ye-microscopic ngexesha lokuvezwa okulinganiselweyo. Ngokusebenzisa uphando oluqhubekayo kunye novavanyo, abaphandi benze uphuculo oluninzi kuyilo lwemveliso kunye noyilo lokudlulisela ukukhanya kwe-ultraviolet ephindaphindwayo ephezulu. Itekhnoloji yohlalutyo lwe-spectral ephucukileyo edityaniswe nomthombo wokukhanya we-ultraviolet ephindaphindwayo ephezulu isetyenzisiwe ukufezekisa umlinganiselo ophezulu wesakhiwo sezinto kunye nenkqubo ye-elektroniki enamandla.
Ukusetyenziswa kwemithombo yokukhanya okugqithisileyo kwe-ultraviolet, njengemilinganiselo ye-angle resolved electron spectroscopy (ARPES), kufuna ukukhanya okugqithisileyo kwe-ultraviolet ukuze kukhanyise isampuli. Ii-electron ezikumphezulu wesampuli ziyavuselelwa kwimeko eqhubekayo kukukhanya okugqithisileyo kwe-ultraviolet, kwaye amandla e-kinetic kunye nokukhupha I-Angle yee-photoelectron ziqulethe ulwazi lwesakhiwo sebhendi yesampuli. I-electron analyzer enomsebenzi wesisombululo se-Angle ifumana ii-photoelectron ezirhabaxa kwaye ifumana isakhiwo sebhendi kufutshane nebhendi ye-valence yesampuli. Kwi-frequency ephantsi yokuphindaphinda umthombo wokukhanya okugqithisileyo kwe-ultraviolet, kuba i-single pulse yayo inenani elikhulu lee-photon, iya kuvusa inani elikhulu lee-photoelectron kumphezulu wesampuli ngexesha elifutshane, kwaye ukusebenzisana kweCoulomb kuya kuzisa ukwanda okukhulu kokusasazwa kwamandla e-photoelectron kinetic, okubizwa ngokuba yi-space charge effect. Ukuze kuncitshiswe impembelelo ye-space charge effect, kuyimfuneko ukunciphisa ii-photoelectron ezikwi-pulse nganye ngelixa kugcinwa i-photon flux eqhubekayo, ngoko ke kuyimfuneko ukuqhubailezangokuphindaphinda okuphezulu ukuvelisa umthombo wokukhanya okugqithisileyo kwe-ultraviolet kunye nokuphindaphinda okuphezulu.
Itekhnoloji yokuphucula udonga lwe-resonance ifezekisa ukuveliswa kwee-harmonics eziphezulu kwi-frequency yokuphindaphinda kwe-MHz
Ukuze kufunyanwe umthombo wokukhanya we-ultraviolet ogqithisileyo onesantya sokuphindaphinda esifikelela kwi-60 MHz, iqela likaJones kwiYunivesithi yaseBritish Columbia e-United Kingdom lenze i-high order harmonic generation kwi-femtosecond resonance enhancement cavity (fsEC) ukuze kufezekiswe umthombo wokukhanya we-ultraviolet ogqithisileyo kwaye bawusebenzise kwiimvavanyo ze-angular resolved electron spectroscopy (Tr-ARPES) ezixazululwe ngexesha. Umthombo wokukhanya unako ukuhambisa i-photon flux engaphezulu kwe-1011 yeenombolo ze-photon ngomzuzwana kunye ne-harmonic enye kwisantya sokuphindaphinda se-60 MHz kuluhlu lwamandla oluyi-8 ukuya kwi-40 eV. Basebenzise inkqubo ye-ytterbium-doped fiber laser njengomthombo wembewu ye-fsEC, kwaye balawula iimpawu ze-pulse ngokusebenzisa uyilo lwenkqubo ye-laser eyenzelwe wena ukunciphisa ingxolo ye-carrier envelope offset frequency (fCEO) kunye nokugcina iimpawu ezilungileyo ze-pulse compression ekupheleni kwekhonkco le-amplifier. Ukuze bafezekise ukuphuculwa kwe-resonance okuzinzileyo ngaphakathi kwe-fsEC, basebenzisa ii-loops ezintathu zolawulo lwe-servo ukulawula impendulo, nto leyo ekhokelela ekuzinzisweni okusebenzayo kwiidigri ezimbini zenkululeko: ixesha lokujika nokubuya kwe-pulse ngaphakathi kwe-fsEC lihambelana nexesha le-laser pulse, kunye notshintsho lwesigaba somthwali wentsimi yombane ngokubhekiselele kwi-pulse envelope (oko kukuthi, isigaba se-carrier envelope, ϕCEO).
Ngokusebenzisa igesi ye-krypton njengegesi esebenzayo, iqela lophando lifikelele ekuvelisweni kwee-harmonics eziphezulu kwi-fsEC. Benza umlinganiselo we-Tr-ARPES we-graphite baza babona ukufudumala okukhawulezayo kunye nokuphindaphinda okucothayo kwee-electron ezingasebenzi kakuhle, kunye nokuguquguquka kweemeko ezingasebenzi kakuhle ezisebenza ngqo kufutshane nenqanaba le-Fermi ngaphezulu kwe-0.6 eV. Lo mthombo wokukhanya ubonelela ngesixhobo esibalulekileyo sokufunda ulwakhiwo lwe-elektroniki lwezinto ezintsonkothileyo. Nangona kunjalo, ukuveliswa kwee-harmonics eziphezulu kwi-fsEC kuneemfuno eziphezulu kakhulu zokubonakalisa, ukuhlawula ukusasazeka, ukulungiswa kakuhle kobude be-cavity kunye nokutshixa kwe-synchronization, okuya kuchaphazela kakhulu i-enhancement multiple ye-resonance-enhanced cavity. Kwangaxeshanye, impendulo yesigaba esingeyo-linear ye-plasma kwindawo ephambili ye-cavity nayo ingumceli mngeni. Ke ngoko, okwangoku, olu hlobo lomthombo wokukhanya aluzange lube yi-ultraviolet eqhelekileyo.umthombo wokukhanya ophezulu we-harmonic.
Ixesha leposi: Epreli-29-2024