Intuthuko ku-ultraviolet eyingozi kakhuluubuchwepheshe bomthombo wokukhanya
Eminyakeni yamuva nje, imithombo ye-harmonic ephezulu ye-ultraviolet idonsele ukunaka okukhulu emkhakheni we-electron dynamics ngenxa yokuhambisana kwayo okuqinile, isikhathi esifushane sokushaya kwenhliziyo kanye namandla aphezulu e-photon, futhi isetshenziswe ezifundweni ezahlukahlukene ze-spectral kanye ne-imaging. Ngokuthuthuka kobuchwepheshe, lokhuumthombo wokukhanyaithuthuka iye emvamisa yokuphindaphinda okuphezulu, i-photon flux ephezulu, amandla aphezulu e-photon kanye nobubanzi obufushane bokushaya kwenhliziyo. Lokhu kuthuthuka akugcini nje ngokuthuthukisa isinqumo sokulinganisa semithombo yokukhanya kwe-ultraviolet eqile, kodwa futhi kunikeza amathuba amasha ezindlela zokuthuthukiswa kobuchwepheshe besikhathi esizayo. Ngakho-ke, ucwaningo olujulile kanye nokuqonda komthombo wokukhanya kwe-ultraviolet eqile okuphindaphindayo kubaluleke kakhulu ekuqondeni nasekusebenziseni ubuchwepheshe obusezingeni eliphezulu.
Ngokulinganiswa kwe-electron spectroscopy ezikalini zesikhathi se-femtosecond kanye ne-attosecond, inani lemicimbi elilinganiswe ku-beam eyodwa livame ukunganeli, okwenza imithombo yokukhanya ephindaphindwayo ephansi inganele ukuthola izibalo ezinokwethenjelwa. Ngesikhathi esifanayo, umthombo wokukhanya one-photon flux ephansi uzonciphisa isilinganiso sesignali-kuya-kumsindo se-imaging microscopic ngesikhathi sokuvezwa okulinganiselwe. Ngokuhlola okuqhubekayo kanye nokuhlola, abacwaningi benze intuthuko eminingi ekuthuthukisweni kwesivuno kanye nomklamo wokudlulisa ukukhanya kwe-ultraviolet okuphindaphindwayo okuphakeme. Ubuchwepheshe bokuhlaziya i-spectral obuthuthukisiwe obuhlanganiswe nomthombo wokukhanya we-ultraviolet ophindaphindwayo ophakeme busetshenziswe ukufeza ukulinganiswa okunembile kwesakhiwo sezinto kanye nenqubo ye-elekthronikhi enamandla.
Ukusetshenziswa kwemithombo yokukhanya kwe-ultraviolet exakile, njengezilinganiso ze-electron spectroscopy (ARPES) ezixazululiwe nge-angular, kudinga ukukhanya kwe-ultraviolet exakile ukuze kukhanye isampula. Ama-electron aphezu kwesampula ashukunyiswa yisimo esiqhubekayo ngokukhanya kwe-ultraviolet exakile, kanti amandla e-kinetic kanye nokukhishwa kwe-Angle yama-photoelectron aqukethe ulwazi lwesakhiwo sebhendi yesampula. I-electron analyzer enomsebenzi we-Angle resolution ithola ama-photoelectron akhishwa imisebe futhi ithola isakhiwo sebhendi eduze kwebhendi ye-valence yesampula. Ngomthombo wokukhanya we-ultraviolet ophindaphindayo ophansi, ngoba i-single pulse yayo iqukethe inani elikhulu lama-photon, izovusa inani elikhulu lama-photoelectron ebusweni besampula ngesikhathi esifushane, futhi ukusebenzisana kwe-Coulomb kuzoletha ukwanda okukhulu kokusatshalaliswa kwamandla e-photoelectron kinetic, okubizwa ngokuthi umphumela we-space charge. Ukuze kuncishiswe ithonya lomphumela we-space charge, kubalulekile ukunciphisa ama-photoelectron aqukethwe ku-pulse ngayinye ngenkathi kugcinwa i-photon flux engaguquki, ngakho-ke kuyadingeka ukuqhubai-laserngemvamisa ephezulu yokuphindaphinda ukuze kukhiqizwe umthombo wokukhanya we-ultraviolet owedlulele onemvamisa ephezulu yokuphindaphinda.
Ubuchwepheshe be-resonance obuthuthukisiwe buveza ukukhiqizwa kwama-harmonics aphezulu ku-frequency yokuphindaphinda kwe-MHz
Ukuze kutholakale umthombo wokukhanya we-ultraviolet owedlulele onesilinganiso sokuphindaphinda esifika ku-60 MHz, ithimba likaJones eNyuvesi yaseBritish Columbia e-United Kingdom lenze ukukhiqizwa kwe-harmonic ephezulu ku-femtosecond resonance enhancement cavity (fsEC) ukuze kufezwe umthombo wokukhanya we-ultraviolet owedlulele osebenzayo futhi wawusebenzisa ekuhlolweni kwe-angler resolved electron spectroscopy (Tr-ARPES) okuxazululwe isikhathi. Umthombo wokukhanya uyakwazi ukuletha i-photon flux yezinombolo ze-photon ezingaphezu kuka-1011 ngomzuzwana nge-harmonic eyodwa ngesilinganiso sokuphindaphinda esingu-60 MHz ebangeni lamandla elingu-8 kuya ku-40 eV. Basebenzise uhlelo lwe-fiber laser olufakwe i-ytterbium njengomthombo wembewu we-fsEC, futhi balawula izici ze-pulse ngokusebenzisa umklamo wesistimu ye-laser eyenziwe ngokwezifiso ukuze kuncishiswe umsindo we-carrier envelope offset frequency (fCEO) futhi kugcinwe izici ezinhle ze-pulse compression ekugcineni kwe-amplifier chain. Ukuze bafinyelele ukuthuthukiswa kwe-resonance okuzinzile ngaphakathi kwe-fsEC, basebenzisa izihibe ezintathu zokulawula i-servo ukulawula impendulo, okuholela ekuzinzeni okusebenzayo kumazinga amabili enkululeko: isikhathi sokubuya nokubuyela emuva kokujikeleza kwe-pulse ngaphakathi kwe-fsEC sifana nesikhathi se-laser pulse, kanye nokushintsha kwesigaba senkampani kagesi maqondana ne-pulse envelope (okungukuthi, isigaba se-carrier envelope, ϕCEO).
Ngokusebenzisa igesi ye-krypton njengegesi esebenzayo, ithimba locwaningo lifinyelele ekukhiqizweni kwama-harmonics e-oda eliphezulu ku-fsEC. Benza izilinganiso ze-Tr-ARPES ze-graphite futhi babona ukushiswa okusheshayo kanye nokuhlanganiswa okuhamba kancane kwenani lama-electron angashukunyiswanga ngokushisa, kanye nokuguquguquka kwezimo ezishukunyiswa ngqo ngokushisa eduze kwezinga le-Fermi ngaphezu kwe-0.6 eV. Lo mthombo wokukhanya unikeza ithuluzi elibalulekile lokufunda isakhiwo se-elekthronikhi sezinto eziyinkimbinkimbi. Kodwa-ke, ukukhiqizwa kwama-harmonics e-oda eliphezulu ku-fsEC kunezidingo eziphezulu kakhulu zokukhanya, isinxephezelo sokuhlakazeka, ukulungiswa okuhle kobude be-cavity kanye nokukhiya kokuvumelanisa, okuzothinta kakhulu i-multiple enhanced ye-resonance-enhanced cavity. Ngesikhathi esifanayo, impendulo yesigaba esingeyona i-linear ye-plasma endaweni egxile kuyo ye-cavity nayo iyinselele. Ngakho-ke, njengamanje, lolu hlobo lomthombo wokukhanya aluzange lube yi-ultraviolet eyinhloko.umthombo wokukhanya ophezulu we-harmonic.
Isikhathi sokuthunyelwe: Ephreli-29-2024