Ukuthuthuka kwe-ultraviolet ngokweqileubuchwepheshe bomthombo wokukhanya
Eminyakeni yamuva nje, imithombo ephakeme ye-ultraviolet ephezulu ye-harmonic iye yakhanga ukunaka okubanzi emkhakheni we-electron dynamics ngenxa yokuhlangana kwayo okuqinile, ubude be-pulse obufushane namandla aphezulu we-photon, futhi isetshenziswe ezifundweni ezihlukahlukene ze-spectral ne-imaging. Ngokuthuthuka kobuchwepheshe, lokhuumthombo wokukhanyaithuthukela kufrikhwensi yokuphindaphinda ephezulu, i-photon flux ephakeme, amandla e-photon aphezulu kanye nobubanzi bokushaya kwenhliziyo okufushane. Lokhu kuthuthukiswa akugcini nje ngokuthuthukisa ukulinganiswa kwemithombo yokukhanya kwe-ultraviolet okwedlulele, kodwa futhi kunikeza amathuba amasha ezitayela zesikhathi esizayo zokuthuthukiswa kobuchwepheshe. Ngakho-ke, ukucwaninga okujulile nokuqonda komthombo wokukhanya kwe-ultraviolet okuphindaphinda imvamisa ephezulu kubaluleke kakhulu ukuze ukwazi ukusebenzisa ubuchwepheshe obusezingeni eliphezulu.
Ezilinganisweni ze-electron spectroscopy esikalini sesikhathi se-femtosecond nese-attosecond, inani lezehlakalo ezikalwa ngebhamu eyodwa ngokuvamile alanele, okwenza imithombo yokukhanya ye-refrequency ephansi inganele ukuthola izibalo ezithembekile. Ngesikhathi esifanayo, umthombo wokukhanya one-photon flux ephansi uzonciphisa isilinganiso sesignali-kuya-nomsindo sokuthwebula izithombe ezincane phakathi nesikhathi sokuchayeka esikhawulelwe. Ngokuhlola okuqhubekayo nokuhlola, abacwaningi baye benza intuthuko eminingi ekuthuthukiseni isivuno kanye nomklamo wokudlulisela wokuphindaphinda okuphezulu okuphindaphindwayo kokukhanya kwe-ultraviolet okwedlulele. Ubuchwepheshe bokuhlaziya i-spectral obuthuthukisiwe obuhlanganiswe nemvamisa yokuphindaphinda komthombo wokukhanya okwedlulele kwe-ultraviolet iye yasetshenziswa ukuze kufinyelelwe isilinganiso esiphezulu sokunemba sesakhiwo sezinto ezibonakalayo kanye nenqubo ye-elekthronikhi eguquguqukayo.
Ukusetshenziswa kwemithombo yokukhanya kwe-ultraviolet okwedlulele, njengezilinganiso ze-electron spectroscopy (i-ARPES) exazululiwe angular, kudinga umsebe wokukhanya kwe-ultraviolet okwedlulele ukuze kukhanyiselwe isampula. Ama-electron angaphezulu kwesampula ajabulele isimo esiqhubekayo ngokukhanya kwe-ultraviolet okwedlulele, futhi amandla e-kinetic kanye ne-Engeli yokukhipha yama-photoelectrons aqukethe ulwazi lwesakhiwo sebhendi lesampula. I-electron analyzer enomsebenzi wokulungiswa kwe-engeli ithola ama-photoelectron akhazimulayo futhi ithola isakhiwo sebhendi eduze nebhendi ye-valence yesampula. Ngomthombo wokukhanya we-ultraviolet ephindaphindayo ephansi kakhulu, ngenxa yokuthi ukushaya kwawo okukodwa kuqukethe inani elikhulu lama-photon, kuzojabulisa inani elikhulu lama-photoelectron endaweni yesampula ngesikhathi esifushane, futhi ukusebenzisana kwe-Coulomb kuzoletha ukwanda okukhulu kokusabalalisa. amandla e-photoelectron kinetic, abizwa ngokuthi umphumela wokushaja isikhala. Ukuze unciphise umthelela womphumela wokushaja kwesikhala, kuyadingeka ukunciphisa ama-photoelectrons aqukethwe ku-pulse ngayinye ngenkathi kugcinwa i-photon flux eqhubekayo, ngakho-ke kuyadingeka ukushayelalasernemvamisa yokuphindaphinda ephezulu ukukhiqiza umthombo wokukhanya we-ultraviolet ngokweqile nemvamisa yokuphindaphinda okuphezulu.
Ubuchwepheshe be-resonance obuthuthukisiwe be-cavity bubona ukukhiqizwa kwama-harmonics wokuhleleka okuphezulu kumafrikhwensi wokuphindaphinda we-MHz
Ukuze kutholwe umthombo wokukhanya kwe-ultraviolet ngokwedlulele ngezinga lokuphindaphinda elingafika ku-60 MHz, ithimba likaJones eNyuvesi yaseBritish Columbia e-United Kingdom lenze isizukulwane se-harmonic esisezingeni eliphezulu endaweni yokuthuthukisa i-femtosecond resonance enhancement cavity (fsEC) ukuze kuzuzwe umphumela ongokoqobo. umthombo wokukhanya kwe-ultraviolet okwedlulele futhi wakusebenzisa ekuhlolweni kwe-electron spectroscopy (Tr-ARPES) exazululwe ye-angular exazululwe isikhathi. Umthombo wokukhanya uyakwazi ukuletha i-photon flux yezinombolo ze-photon ezingaphezu kwezingu-1011 ngomzuzwana nge-harmonic eyodwa ngenani lokuphindaphinda elingu-60 MHz kububanzi bamandla obungu-8 ukuya ku-40 eV. Basebenzise isistimu ye-fiber laser ye-ytterbium-doped njengomthombo wembewu ye-fsEC, futhi balawula izici ze-pulse ngokusebenzisa idizayini yesistimu ye-laser eyenziwe ngokwezifiso ukuze banciphise umsindo we-carrier envelope offset frequency (fCEO) nokugcina izici ezinhle zokucindezelwa kwe-pulse ekupheleni kweketango le-amplifier. Ukuze bathole ukuthuthukiswa kwe-resonance ezinzile ngaphakathi kwe-fsEC, basebenzisa amalophu okulawula ama-servo amathathu ukuze balawule impendulo, okuholela ekuzinzeni okusebenzayo ngamadigri amabili enkululeko: isikhathi sohambo lokuya nokubuya sokuhamba ngebhayisikili ngaphakathi kwe-fsEC sifana nesikhathi sokushaywa kwe-laser, kanye nokushintsha kwesigaba. yesiphathi senkambu kagesi maqondana nemvilophu ye-pulse (okungukuthi, isigaba semvilophu yenkampani, ϕCEO).
Ngokusebenzisa igesi ye-krypton njengegesi esebenzayo, ithimba labacwaningi lizuze ukukhiqizwa kwama-harmonics asezingeni eliphezulu ku-fsEC. Benze izilinganiso ze-Tr-ARPES zegraphite futhi babona ukushisa okushisayo okusheshayo nokuhlanganisa kabusha okunensayo okwalandela kwama-electron abantu abangajabulile, kanye namandla ezifunda ezingajabulile ngokuqondile eduze nezinga le-Fermi ngaphezu kuka-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 eziphakeme kakhulu zokubonakala, isinxephezelo sokuhlakazeka, ukulungiswa okuhle kobude be-cavity kanye nokukhiya kokuvumelanisa, okuzothinta kakhulu ukuthuthukiswa kokuphindaphinda kwe-resonance-enhanced cavity. Ngesikhathi esifanayo, impendulo yesigaba esingaqondile se-plasma endaweni ebalulekile ye-cavity nayo iyinselele. Ngakho-ke, okwamanje, lolu hlobo lomthombo wokukhanya aluzange lube yi-ultraviolet eyeqisayo evamileumthombo wokukhanya we-harmonic ophezulu.
Isikhathi sokuthumela: Apr-29-2024