Anyị na-eji fotoemission spectroscopy nke oge na akụkụ edoziri (tr-ARPES) iji nyochaa nnyefe chaja ngwa ngwa na epitaxial heterostructure nke ejiri monolayer WS2 na graphene mee. Heterostructure a na-ejikọta uru nke semiconductor oghere kpọmkwem yana njikọ siri ike nke spin-orbit na mmekọrịta siri ike nke ihe ọkụ na nke ndị na-ebu ibu semimetal na-anabata enweghị oke nwere nnukwu ngagharị na ndụ ogologo ntụgharị. Anyị na-achọpụta na, mgbe photoexcitation na resonance na A-exciton na WS2 gasịrị, oghere photoexcited na-agafe ngwa ngwa na oyi akwa graphene ebe elektrọn photoexcited na-anọgide na oyi akwa WS2. A chọpụtara na ọnọdụ nwa oge nke kewapụrụ chaja nwere ndụ nke ~ 1 ps. Anyị na-akọwapụta ihe anyị chọpụtara na ọdịiche dị na oghere nkewa nke sitere na nhazi nke eriri WS2 na graphene dịka ekpughere site na ARPES dị elu. Na njikọta ya na mkpali anya spin-selective, heterostructure WS2/graphene a nyochachara nwere ike inye ikpo okwu maka ntụtụ ntụgharị anya dị irè na graphene.
Ọdịdị nke ọtụtụ ihe dị iche iche nwere akụkụ abụọ emepeela ohere ịmepụta ụdị heterostructures ọhụrụ dị gịrịgịrị nke nwere ọrụ ọhụrụ kpamkpam dabere na nyocha dielectric ahaziri ahazi na mmetụta dị iche iche nke nso nso kpatara (1-3). Emezuola ngwaọrụ ndị na-egosi ụkpụrụ maka ojiji n'ọdịnihu n'ọhịa nke eletrọniki na optoelectronics (4-6).
N'ebe a, anyị na-elekwasị anya na epitaxial van der Waals heterostructures nke nwere monolayer WS2, semiconductor nwere njikọ siri ike na spin-orbit na nnukwu nkewa nke nhazi band n'ihi agbajiela inversion symmetry (7), na monolayer graphene, semimetal nwere nhazi band conical na ngagharị ibu dị elu (8), nke a kụrụ na hydrogen-ended SiC(0001). Ihe ngosi mbụ maka mbufe chaja ngwa ngwa (9–15) na mmetụta njikọ spin-orbit nke nso nso kpatara (16–18) na-eme ka WS2/graphene na heterostructures ndị yiri ya na-ekwe nkwa maka ngwa optoelectronic (19) na optospintronic (20) n'ọdịnihu.
Anyị malitere ikpughe ụzọ ntụrụndụ nke ụzọ abụọ elektrọn-hole photogenerated na WS2/graphene site na iji fotoemission spectroscopy nke oge na akụkụ edoziri (tr-ARPES). Maka ebumnuche ahụ, anyị na-akpali heterostructure site na 2-eV pump pulses resonant na A-exciton na WS2 (21, 12) ma na-ewepụ photoelectrons na probe pulse nke oge abụọ na ike photon 26-eV. Anyị na-ekpebi ike kinetic na akụkụ mwepụ nke photoelectrons site na iji ihe nyocha hemispherical dị ka ọrụ nke igbu oge pump-probe iji nweta ohere na momentum-, ike-, na oge edoziri. Mkpebi ike na oge bụ 240 meV na 200 fs, n'otu n'otu.
Nsonaazụ anyị na-enye ihe akaebe kpọmkwem maka mbufe chaja ngwa ngwa n'etiti oyi akwa a haziri ahazi nke epitaxial, na-akwado ihe ngosi mbụ dabere na usoro anya niile na heterostructures ndị yiri ya nke ejiri aka chịkọtara yana nhazi azimuthal nke oyi akwa (9-15). Na mgbakwunye, anyị na-egosi na mbufe chaja a enweghị ihe ọ bụla. Nha anyị na-ekpughe ọnọdụ nwa oge nke kewapụrụ chaja nke a na-ahụbeghị na mbụ yana elektrọn fotomotivated na oghere dị na oyi akwa WS2 na graphene, n'otu n'otu, nke na-adị ndụ maka ~ 1 ps. Anyị na-akọwa nchọpụta anyị n'ihe gbasara ọdịiche dị na oghere nkewa maka nnyefe elektrọn na oghere nke sitere na nhazi nke eriri WS2 na graphene dịka ekpughere site na ARPES dị elu. Ejikọtara ya na mkpali anya spin- na ndagwurugwu-nhọrọ (22-25) WS2/graphene heterostructures nwere ike inye ikpo okwu ọhụrụ maka ntinye anya ultrafast optical spin na graphene nke ọma.
Foto 1A na-egosi nha ARPES dị elu nke e nwetara site na oriọna helium nke nhazi eriri ahụ n'akụkụ ntụziaka ΓK nke epitaxial WS2/graphene heterostructure. A hụrụ na cone Dirac nwere oghere na isi Dirac dị ihe dịka 0.3 eV n'elu ike kemịkalụ nha ahụ. A hụrụ elu nke eriri valence WS2 nke na-agbagharị agbagharị dị ihe dịka 1.2 eV n'okpuru ike kemịkalụ nha ahụ.
(A) A tụrụ ọkụ eletrik nha nhata n'akụkụ ntụziaka ΓK site na iji oriọna helium na-enweghị polarized. (B) Ọwa foto maka oge nyocha mgbapụta na-adịghị mma nke ejiri p-polarized extreme ultraviolet pulses na ike photon 26-eV tụọ. Ahịrị isi awọ na uhie gbara agba na-egosi ọnọdụ nke profaịlụ ahịrị ejiri wepụta ọnọdụ elu oge na Fig. 2. (C) Mgbanwe nke ọkpọkọ foto 200 fs mgbe ọkụ ọkụ gasịrị na ike ọkpọkọ foto nke 2 eV nwere mmetụta ọkpọkọ nke 2 mJ/cm2. A na-egosi uru na mfu nke fotoelectrons na uhie na acha anụnụ anụnụ, n'otu n'otu. Igbe ndị ahụ na-egosi mpaghara njikọta maka akara ọkpọkọ probe egosiri na Fig. 3.
Foto 1B na-egosi foto tr-ARPES nke nhazi eriri dị nso na WS2 na isi K nke graphene tụrụ na 100-fs oke ultraviolet na ike photon 26-eV na nkwụsịtụ pump-probe na-adịghị mma tupu ọbịbịa nke pump pulse. N'ebe a, a naghị edozi nkewa spin n'ihi mmebi ihe nlele na ọnụnọ nke pump pulse 2-eV nke na-eme ka chajị oghere gbasaa nke atụmatụ spectral. Foto 1C na-egosi mgbanwe nke pump kpatara nke photocurrent gbasara Foto 1B na nkwụsịtụ pump-probe nke 200 fs ebe akara pump-probe ruru oke ya. Agba uhie na acha anụnụ anụnụ na-egosi uru na mfu nke photoelectrons, n'otu n'otu.
Iji nyochaa mgbanwe ndị a bara ụba nke ọma, anyị na-ebu ụzọ chọpụta ọnọdụ elu nke oge nke eriri valence WS2 na eriri graphene π n'akụkụ ahịrị ndị a gbagọrọ agbagọ na Fig. 1B dịka akọwara nke ọma na Ihe Mgbakwunye. Anyị na-achọpụta na eriri valence WS2 na-agbanwe site na 90 meV (Fig. 2A) na eriri graphene π na-agbada site na 50 meV (Fig. 2B). A chọpụtara na ndụ exponential nke mgbanwe ndị a bụ 1.2 ± 0.1 ps maka eriri valence nke WS2 na 1.7 ± 0.3 ps maka eriri graphene π. Mgbanwe elu ndị a na-enye ihe akaebe mbụ nke chaja nwa oge nke oyi akwa abụọ ahụ, ebe chaja dị mma (na-adịghị mma) ọzọ na-abawanye (na-ebelata) ike njikọ nke ọnọdụ eletrọnịkị. Rịba ama na mmụba nke eriri valence WS2 bụ maka akara mgbapụta-nchọpụta pụtara ìhè na mpaghara nke igbe ojii ahụ akara na Fig. 1C.
Mgbanwe n'ọnọdụ kachasị elu nke eriri valence WS2 (A) na graphene π-band (B) dịka ọrụ nke igbu oge pump-probe yana nha nha exponential (ahịrị ndị dị arọ). Ndụ nke mgbanwe WS2 na (A) bụ 1.2 ± 0.1 ps. Ndụ nke mgbanwe graphene na (B) bụ 1.7 ± 0.3 ps.
Na-esote, anyị na-ejikọta akara mgbapụta ahụ n'elu ebe ndị igbe agba dị na Fig. 1C gosiri ma na-akọwa ọnụọgụgụ ndị si na ya pụta dị ka ọrụ nke igbu oge mgbapụta ahụ na Fig. 3. Ngọngọ 1 na Fig. 3 na-egosi ike nke ndị na-ebu foto dị nso na ala nke eriri conduction nke oyi akwa WS2 na ndụ nke 1.1 ± 0.1 ps enwetara site na ntinye exponential na data (lee Ihe Ndị Ọzọ).
Ihe ndị a na-akpọ "pump-probe traces" dịka ọrụ nke igbu oge enwetara site na ijikọta fotocurrent n'elu mpaghara nke igbe ndị dị na Fig. 1C gosiri. Ahịrị ndị ahụ dị oke mkpa dabara na data ahụ. Usoro (1) Ọnụọgụ ndị na-ebu ihe na-agafe agafe na eriri conduction nke WS2. Usoro (2) Usoro probe nke ọkpọkọ nke ọkpọkọ nke graphene n'elu ike kemịkalụ nhazi. Usoro (3) Usoro probe nke ọkpọkọ nke ọkpọkọ nke graphene n'okpuru ike kemịkalụ nhazi. Usoro (4) Usoro probe nke ọkpọkọ nke net na eriri valence nke WS2. Achọpụtara na ndụ niile bụ 1.2 ± 0.1 ps na (1), 180 ± 20 fs (uru) na ~2 ps (mfu) na (2), na 1.8 ± 0.2 ps na (3).
N'ime usoro 2 na 3 nke Fig. 3, anyị na-egosi akara mgbapụta nke graphene π-band. Anyị na-achọpụta na uru nke elektrọn karịrị ike kemịkalụ nhazi (usoro 2 na Fig. 3) nwere ndụ dị mkpụmkpụ karịa (180 ± 20 fs) ma e jiri ya tụnyere mfu nke elektrọn n'okpuru ike kemịkalụ nhazi (1.8 ± 0.2 ps na usoro 3 Fig. 3). Ọzọkwa, a chọpụtara na mmụba mbụ nke fotocurrent na usoro 2 nke Fig. 3 na-aghọ mfu na t = 400 fs yana ndụ nke ~ 2 ps. A chọpụtara na enweghị asymmetry dị n'etiti uru na mfu na mgbaàmà mgbapụta nke graphene monolayer ekpuchighị ekpuchi (lee fig. S5 na Ihe Mgbakwunye), na-egosi na asymmetry bụ nsonaazụ nke njikọ dị n'etiti akwa na heterostructure WS2/graphene. Nleba anya nke uru dị mkpụmkpụ na mfu dị ogologo n'elu na n'okpuru ike kemịkalụ nhazi, n'otu n'otu, na-egosi na a na-ewepụ elektrọn nke ọma na oyi akwa graphene mgbe a na-ese foto nke heterostructure. N'ihi ya, oyi akwa graphene na-aghọ chajị nke ọma, nke kwekọrọ na mmụba nke ike njikọ nke π-band dị na Fig. 2B. Mgbanwe nke π-band na-ewepụ ọdụ ike dị elu nke nkesa Fermi-Dirac site na ike kemịkalụ nhazi, nke na-akọwa obere mgbanwe nke akara nke akara mgbapụta-probe na usoro 2 nke Fig. 3. Anyị ga-egosi n'okpuru na mmetụta a na-eme ka ọ dịkwuo mma site na mfu oge nke elektrọn na π-band.
Ihe ngosi a na-akwado site na akara nyocha ọkpọkọ nke eriri WS2 na usoro nke 4 nke Fig. 3. E nwetara data ndị a site na ijikọta ọnụọgụgụ n'elu mpaghara nke igbe ojii nyere na Fig. 1B nke na-ejide elektrọn ndị a na-ewepụta site na eriri valence na nkwụsịtụ nyocha ọkpọkọ niile. N'ime ogwe njehie nnwale, anyị ahụghị ihe ngosi ọ bụla maka ọnụnọ nke oghere na eriri valence nke WS2 maka nkwụsịtụ nyocha ọkpọkọ ọ bụla. Nke a na-egosi na, mgbe a gbasịrị foto, a na-emegharị oghere ndị a ngwa ngwa na obere oge ma e jiri ya tụnyere mkpebi oge anyị.
Iji nye ihe akaebe ikpeazụ maka echiche anyị nke nkewa chaja ngwa ngwa na heterostructure WS2/graphene, anyị na-ekpebi ọnụọgụ oghere ndị e zigara na oyi akwa graphene dịka akọwara n'ụzọ zuru ezu na Ihe Mgbakwunye. Na nkenke, e tinyere nkesa eletrọniki nwa oge nke π-band na nkesa Fermi-Dirac. E mesịa gbakọọ ọnụọgụ oghere site na uru ndị a rụpụtara maka ike kemịkalụ nwa oge na okpomọkụ eletrọniki. A na-egosi nsonaazụ ya na Fig. 4. Anyị chọpụtara na a na-ebufe ọnụọgụgụ oghere ~5 × 1012/cm2 site na WS2 gaa na graphene na ndụ exponential nke 1.5 ± 0.2 ps.
Mgbanwe nke ọnụọgụ oghere dị na π-band dịka ọrụ nke igbu oge mgbapụta yana nhazi exponential nke na-enye ndụ nke 1.5 ± 0.2 ps.
Site na ihe ndị a chọpụtara na Fig. 2 ruo 4, foto a na-ahụ anya maka mbufe chaja kachasị ọsọ na heterostructure WS2/graphene na-apụta (Fig. 5). Foto mkpali nke heterostructure WS2/graphene na 2 eV na-ejupụta A-exciton nke ukwuu na WS2 (Fig. 5A). Mkpalite eletrọnịkị ndị ọzọ na-agafe ebe Dirac dị na graphene yana n'etiti eriri WS2 na graphene nwere ike ime ike mana ọ naghị arụ ọrụ nke ọma. Electron sitere na graphene π-band na-ejupụta oghere ndị a na-akpali akpali na eriri valence nke WS2 na obere oge ma e jiri ya tụnyere mkpebi oge anyị (Fig. 5A). Electron ndị a na-akpali akpali na eriri conduction nke WS2 nwere ndụ ndụ nke ~1 ps (Fig. 5B). Agbanyeghị, ọ na-ewe ~2 ps iji mejupụta oghere ndị dị na eriri graphene π (Fig. 5B). Nke a na-egosi na, ewezuga nnyefe elektrọn kpọmkwem n'etiti eriri conduction WS2 na eriri graphene π, a ga-atụle ụzọ ezumike ndị ọzọ—ikekwe site na ọnọdụ ntụpọ (26)—iji ghọta ike zuru oke.
(A) Foto mkpali mgbe resonance na WS2 A-exciton na 2 eV na-etinye elektrọn n'ime eriri conduction nke WS2. Electron sitere na graphene π-band na-ejupụta oghere ndị kwekọrọ na eriri valence nke WS2 ozugbo. (B) Ndị na-ebu foto ihe mkpali na eriri conduction nke WS2 nwere ndụ nke ~ 1 ps. Oghere ndị dị na eriri graphene π-band na-adị ndụ ruo ~ 2 ps, na-egosi mkpa ọwa mgbasa ozi ndị ọzọ nke akụ ndị a gbajiri agbaji gosiri. Ahịrị ojii gbara okirikiri na (A) na (B) na-egosi mgbanwe eriri na mgbanwe na ike kemịkal. (C) N'ọnọdụ nwa oge, a na-ana akwa WS2 n'ụzọ na-adịghị mma ebe akwa graphene na-ana chajị nke ọma. Maka mkpali nhọrọ spin-selective nwere ìhè gbara okirikiri, a na-atụ anya na elektrọn foto ihe mkpali na WS2 na oghere ndị kwekọrọ na graphene ga-egosi polarization nke na-emegide ya.
N'ọnọdụ mgbanwe, elektrọn ndị a na-akpali akpali na-ebi n'ime eriri conduction nke WS2 ebe oghere ndị a na-akpali akpali dị na eriri π nke graphene (Foto 5C). Nke a pụtara na oyi akwa WS2 na-ada ụda na-adịghị mma ma oyi akwa graphene na-ada ụda nke ọma. Nke a na-akọwa maka mgbanwe elu oge (Foto 2), asymmetry nke akara pump-probe graphene (n'akụkụ 2 na 3 nke Fig. 3), enweghị oghere na eriri valence nke WS2 (n'akụkụ 4 Fig. 3), yana oghere ndị ọzọ na eriri graphene π (Foto 4). Ndụ nke ọnọdụ a kewapụrụ chajị bụ ∼1 ps (n'akụkụ 1 Fig. 3).
A hụla ọnọdụ nwa oge ndị yiri nke ahụ nke kewapụrụ n'ụgwọ na heterostructures ndị yiri ya nke van der Waals nke e ji semiconductors abụọ kwụ ọtọ mee nke nwere nhazi band nke ụdị nke abụọ na bandgap gbagọrọ agbagọ (27–32). Mgbe foto mkpali gasịrị, a chọpụtara na elektrọn na oghere ndị ahụ na-aga ngwa ngwa na ala nke band conduction na elu nke band valence, n'otu n'otu, nke dị na akwa dị iche iche nke heterostructure (27–32).
N'ihe gbasara nhazi WS2/graphene anyị, ebe kachasị mma maka elektrọn na oghere dị na ọkwa Fermi na akwa graphene ọla. Ya mere, mmadụ ga-atụ anya na elektrọn na oghere na-agafe ngwa ngwa na graphene π-band. Agbanyeghị, nha anyị na-egosi nke ọma na nnyefe oghere (<200 fs) dị irè karịa nnyefe elektrọn (~1 ps). Anyị na-akọwa nke a na nhazi ike nke WS2 na eriri graphene dịka ekpughere na Fig. 1A nke na-enye ọnụọgụgụ dị ukwuu nke ọnọdụ ikpeazụ dị maka nnyefe oghere ma e jiri ya tụnyere nnyefe elektrọn dịka a tụrụ anya ya n'oge na-adịbeghị anya (14, 15). N'okwu a, na-ewere bandgap ~2 eV WS2, graphene Dirac point na ike nhazi kemịkalụ dị ~0.5 na ~0.2 eV n'elu etiti bandgap WS2, n'otu n'otu, na-agbaji symmetry electron-hole. Anyị chọpụtara na ọnụọgụgụ ọnọdụ ikpeazụ dị maka nnyefe oghere dị ihe dịka okpukpu isii karịa maka nnyefe elektrọn (lee ihe mgbakwunye), ọ bụ ya mere a na-atụ anya na nnyefe oghere ga-adị ngwa ngwa karịa nnyefe elektrọn.
Agbanyeghị, foto zuru oke nke nnyefe chaja asymmetric a hụrụ kwesịrị ịtụlekwa njikọta dị n'etiti orbitals ndị mejupụtara ọrụ ebili mmiri A-exciton na WS2 na graphene π-band, n'otu n'otu, ọwa mgbasa elektrọn-electron na elektrọn-phonon dị iche iche gụnyere ihe mgbochi nke nchekwa momentum, ike, spin, na pseudospin tinyere, mmetụta nke oscillations plasma (33), yana ọrụ nke mkpali displacitive nke oscillations phonon coherent nke nwere ike imezi nnyefe chaja (34, 35). Ọzọkwa, mmadụ nwere ike ịkọ nkọ ma ọnọdụ nnyefe chaja a hụrụ gụnyere excitons nnyefe chaja ma ọ bụ ụzọ abụọ electron-hole efu (lee Ihe Ndị Ọzọ). A chọrọ nyocha echiche ndị ọzọ gafere oke nke akwụkwọ a iji mee ka okwu ndị a doo anya.
Na nchịkọta, anyị ejirila tr-ARPES mụọ mbufe chajị interlayer nke dị oke ọsọ n'ime epitaxial WS2/graphene heterostructure. Anyị chọpụtara na, mgbe obi dị anyị ụtọ na resonance na A-exciton nke WS2 na 2 eV, oghere photoexcited na-agafe ngwa ngwa na oyi akwa graphene ebe elektrọn photoexcited na-anọgide na oyi akwa WS2. Anyị kwuru na nke a bụ eziokwu na ọnụọgụgụ ọnọdụ ikpeazụ dị maka mbufe oghere karịrị maka mbufe elektrọn. A chọpụtara na ndụ nke ọnọdụ oge nke kewapụrụ chajị dị ihe dịka 1 ps. Na njikọta ya na mkpali anya nke na-ahọrọ spin-selective site na iji ìhè okirikiri (22-25), mbufe chajị ultrafast a hụrụ nwere ike iso ya na mbufe spin. N'okwu a, enwere ike iji heterostructure WS2/graphene a nyochachara maka ntụtụ ntụgharị anya dị irè na graphene nke na-ebute ngwaọrụ optospintronic ọhụrụ.
A kụrụ ihe nlele graphene na wafers 6H-SiC(0001) nke azụmaahịa sitere na SiCrystal GmbH. Wafers N-doped dị n'akụkụ ya ma nwee obere ihe dị n'okpuru 0.5°. E ji hydrogen kpụọ ihe mejupụtara SiC iji wepụ ihe ndị a na-akọcha ma nweta ala dị larịị mgbe niile. E mechara graphitize elu SiC dị ọcha ma dị larịị site na iji ihe nlele ahụ mee ihe na ikuku Ar na 1300°C maka nkeji 8 (36). N'ụzọ dị otu a, anyị nwetara otu oyi akwa carbon ebe atọ ọ bụla nke atọ nke atọ nke carbon mepụtara njikọ covalent na substrate SiC (37). E mesịa gbanwee oyi akwa a ka ọ bụrụ graphene sp2-hybridized quasi free-standing hole-doped site na hydrogen intercalation (38). A na-akpọ ihe nlele ndị a graphene/H-SiC(0001). Emere usoro ahụ dum na ụlọ ahịa Black Magic azụmahịa site na Aixtron. E mere uto WS2 n'ime ihe nrụpụta ọkụ-mgbidi ọkọlọtọ site na itinye obere nrụgide kemịkalụ na-ekpo ọkụ (39, 40) site na iji ntụ WO3 na S nke nwere oke oke nke 1:100 dị ka ihe ndị na-ebute ụzọ. E debere ntụ WO3 na S na 900 na 200°C, n'otu n'otu. E tinyere ntụ WO3 nso na substrate ahụ. E jiri Argon mee ihe dị ka gas na-ebu ibu nke 8 sccm. E debere nrụgide dị na reactor ahụ na 0.5 mbar. E ji microscopy elektrọn nke abụọ, microscopy ike atọm, Raman, na photoluminescence spectroscopy, yana obere ike electron diffraction mara ihe nlele ndị ahụ. Nha ndị a kpughere mpaghara abụọ dị iche iche nke WS2 otu kristal ebe ma ΓK- ma ọ bụ ΓK'-direction kwekọrọ na ΓK-direction nke oyi akwa graphene. Ogologo akụkụ ngalaba dị iche n'etiti 300 na 700 nm, mkpokọta mkpuchi WS2 dịkwa ihe dịka 40%, nke dabara adaba maka nyocha ARPES.
E jiri ihe nyocha hemispherical (SPECS PHOIBOS 150) mee nnwale ARPES nke na-anaghị agbanwe agbanwe maka ike elektrọn na momentum. E jiri radieshon He Iα nke na-anaghị agbanwe agbanwe (21.2 eV) nke isi iyi mgbapụta He dị elu (VG Scienta VUV5000) mee ihe maka nnwale fotoemission niile. Ike na mkpebi akụkụ na nnwale anyị ka mma karịa 30 meV na 0.3° (dakọtara na 0.01 Å−1), n'otu n'otu. E mere nnwale niile na okpomọkụ ụlọ. ARPES bụ usoro dị oke mkpa maka elu. Iji chụpụ fotoelectrons site na oyi akwa WS2 na graphene, ejiri ihe nlele nwere mkpuchi WS2 na-ezughị ezu nke ~40%.
Ntọala tr-ARPES dabere na 1-kHz Titanium:Sapphire amplifier (Coherent Legend Elite Duo). E jiri 2 mJ nke ike mmepụta mee ihe maka imepụta harmonics dị elu na argon. Ìhè ultraviolet dị oke njọ nke si na ya gafere site na grating monochromator na-emepụta 100-fs probe pulses na 26-eV photon ike. E zigara 8mJ nke ike mmepụta amplifier na amplifier parametric optical (HE-TOPAS site na Light Conversion). E jiri okpukpu abụọ nke akara mgbaàmà na 1-eV photon ike na beta barium borate kristal iji nweta 2-eV pump pulses. Ejiri ihe nyocha hemispherical mee nha tr-ARPES (SPECS PHOIBOS 100). Ike na mkpebi oge niile bụ 240 meV na 200 fs, n'otu n'otu.
Ihe ndị ọzọ e dere maka edemede a dị na http://advances.sciencemag.org/cgi/content/full/6/20/eaay0761/DC1.
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Site na Sven Aeschlimann, Antonio Rossi, Mariana Chávez-Cervantes, Razvan Krause, Benito Arnoldi, Benjamin Stadtmüller, Martin Aeschlimann, Stiven Forti, Filippo Fabbri, Camilla Coletti, Isabella Gierz
Anyị na-ekpughe nkewa chaja ngwa ngwa na heterostructure WS2/graphene nke nwere ike ime ka ntụtụ anya na-agbagharị n'ime graphene.
Site na Sven Aeschlimann, Antonio Rossi, Mariana Chávez-Cervantes, Razvan Krause, Benito Arnoldi, Benjamin Stadtmüller, Martin Aeschlimann, Stiven Forti, Filippo Fabbri, Camilla Coletti, Isabella Gierz
Anyị na-ekpughe nkewa chaja ngwa ngwa na heterostructure WS2/graphene nke nwere ike ime ka ntụtụ anya na-agbagharị n'ime graphene.
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Oge ozi: Mee-25-2020