Anyị na-eji oge na akụkụ-edozi fotoemission spectroscopy (tr-ARPES) iji nyochaa nnyefe ultrafast chaja na epitaxial heterostructure mere nke monolayer WS2 na graphene. Nke a heterostructure na-ejikọta abamuru nke semiconductor oghere kpọmkwem na njikọ nke spin-orbit siri ike na mmekọrịta ọkụ siri ike na ndị nke ndị na-ebu ibu na-enweghị ihe mgbochi nke nwere nnukwu njem na ogologo oge ndụ. Anyị na-ahụ na, mgbe photoexcitation na resonance na A-exciton na WS2, foto excited oghere ngwa ngwa na-ebufe n'ime graphene oyi akwa mgbe fotoexcited electrons na-anọgide na WS2 oyi akwa. Achọpụtara ụgwọ ọrụ nkewapụrụ n'oge na-adịghị anya ka ọ nwere oge ndụ nke ~ 1 ps. Anyị na-ekwu na nchoputa anyị bụ ndịiche dị na oghere nke ịgbasasịsịa site na nhazi nke WS2 na band graphene dị ka ARPES dị elu gosipụtara. Na mgbakwunye na mkpali ngwa anya nke ahọpụtara, WS2/graphene heterostructure nke nyochara nwere ike inye ikpo okwu maka ịgbanye ntụtụ anya nke ọma n'ime graphene.
Ịnweta ọtụtụ ihe dị n'akụkụ abụọ dị iche iche emeghewo ohere ịmepụta akwụkwọ akụkọ n'ikpeazụ heterostructures dị mkpa nke nwere ọrụ ọhụrụ zuru oke dabere na nyocha dielectric ahaziri na mmetụta dị iche iche na-ebute nso (1-3). Ihe akaebe nke ụkpụrụ maka ngwa n'ọdịnihu n'ọhịa nke eletrọnịkị na optoelectronics ka emezuru (4-6).
N'ebe a, anyị na-elekwasị anya na epitaxial van der Waals heterostructures nke nwere monolayer WS2, semiconductor oghere kpọmkwem nwere njikọ siri ike na-agba ọsọ na nkewa dị ukwuu nke usoro band n'ihi nhụsianya ntụgharị (7), na monolayer graphene, semimetal. nwere conical band Ọdịdị na oke ibu ihe ngagharị (8), toro na hydrogen-akwụsị SiC (0001). Ngosipụta mbụ maka mbufe ụgwọ ultrafast (9-15) na nso nso-akpata spin-orbit njikọ mmetụta (16-18) na-eme WS2 / graphene na heterostructures ndị yiri ya na-ekwe nkwa ndị ga-aga maka ngwa optoelectronic (19) na optospintronic (20).
Anyị wepụtara ikpughe ụzọ izu ike nke ụzọ abụọ eletrọn-phole emepụtara na WS2/graphene nwere oge fotoemission spectroscopy (tr-ARPES). Maka nzube ahụ, anyị na-akpali heterostructure na 2-eV mgbapụta pulses resonant na A-exciton na WS2 (21, 12) na-ewepụ fotoelectrons na nke abụọ oge-egbu oge nyocha pulse na 26-eV photon ike. Anyị na-ekpebi ike kinetic na ikuku ikuku nke fotoelectrons na onye nyocha nke hemispherical dị ka ọrụ nke mgbapụta mgbapụta iji nweta ohere n'ime ume-, ume-, na ogologo oge na-ebu ihe. Mkpebi ike na oge bụ 240 meV na 200 fs, n'otu n'otu.
Nsonaazụ anyị na-enye ihe akaebe ozugbo maka mbufe ụgwọ ultrafast n'etiti ọkwa epitaxially jikọtara ọnụ, na-akwado ihe ngosi mbụ dabere na usoro ngwa anya niile n'ụdị heterostructures ejiri aka gbakọtara yana nhazi azimuthal nke akwa akwa (9-15). Na mgbakwunye, anyị na-egosi na nnyefe ụgwọ a dị oke asymmetric. Ntụle anyị na-ekpughe ọnọdụ ngbanwe nke ụgwọ anaghị echekwa ya na eletrọn na oghere dị na WS2 na graphene oyi akwa, n'otu n'otu, na-adị ndụ maka ~ 1 ps. Anyị na-akọwa ihe nchoputa anyị n'ihe dị iche na ohere ịgbasa oghere maka eletrọn na mbufe oghere kpatara site na nhazi nke WS2 na band graphene dị ka ARPES dị elu gosipụtara. Ejikọtara ya na mkpali ngwa anya nke na-ahọrọ na ndagwurugwu (22-25) WS2/graphene heterostructures nwere ike ịnye usoro ọhụrụ maka ịgbanye ntụtụ ngwa anya ultrafast nke ọma n'ime graphene.
Ọgụgụ 1A na-egosi nha ARPES dị elu nke enwetara na oriọna helium nke nhazi band n'akụkụ ΓK-ntụziaka nke epitaxial WS2/graphene heterostructure. A na-ahụ cone Dirac ka ọ nwere oghere na ebe Dirac dị ~ 0.3 eV karịa ikike kemịkalụ nha nhata. Achọpụtara elu nke split WS2 valence band ka ọ dị ~ 1.2 eV n'okpuru ikike kemịkalụ nha nhata.
(A) Equilibrium photocurrent tụrụ n'akụkụ ntụzịaka ΓK jiri oriọna helium enweghị atụ. (B) Photocurrent maka igbu oge mgbapụta mgbapụta na-adịghị mma tụrụ ya na p-polarized oke ultraviolet pulses na ike 26-eV photon. Ahịrị isi awọ na-acha uhie uhie na-egosi ọnọdụ nke profaịlụ ahịrị ejiri wepụta ọnọdụ kachasị elu na-agafe agafe na Fig. nke 2mJ/cm2. A na-egosi uru na ọnwụ nke fotoelectrons na uhie na acha anụnụ anụnụ, n'otu n'otu. Igbe ndị ahụ na-egosi mpaghara njikọta maka nchọgharị mgbapụta mgbapụta egosiri na Fig. 3.
Ọnụọgụ 1B na-egosi foto tr-ARPES nke ihe owuwu nke dị nso na WS2 na graphene K-points tụrụ na 100-fs oke ultraviolet pulses na 26-eV photon ike na mgbapụta mgbapụta na-adịghị mma tupu ọbịbịa nke mgbapụta mgbapụta. N'ebe a, a naghị edozi nkewa ahụ n'ihi nbibi sample na ọnụnọ nke pulse 2-eV nke na-eme ka ụgwọ oghere gbasaa n'ime atụmatụ. Ọnụọgụ 1C na-egosi mgbanwe mgbanwe nke mgbapụta nke foto na-eme ka ọ bụrụ ihe gbasara 1B na nkwụsịtụ mgbapụta nke 200 fs ebe mgbapụta mgbapụta na-erute elu ya. Agba uhie na acha anụnụ anụnụ na-egosi uru na ọnwụ nke fotoelectrons, n'otu n'otu.
Iji nyochaa ọnọdụ akụ na ụba a n'ụzọ zuru ezu karị, anyị na-ebu ụzọ chọpụta ọnọdụ kachasị elu nke WS2 valence band na graphene π-band tinyere ahịrị ndị ahụ dị na fig. 1B dịka akọwara n'ụzọ zuru ezu na Ngwa mgbakwunye. Anyị na-achọpụta na WS2 valence band na-agbanwe site na 90 meV (Fig. 2A) na graphene π-band na-agbada site na 50 meV (Fig. 2B). Achọpụtara ogologo oge ndụ nke mgbanwe ndị a bụ 1.2 ± 0.1 ps maka band valence nke WS2 na 1.7 ± 0.3 ps maka graphene π-band. Mgbanwe kachasị elu ndị a na-enye ihe akaebe mbụ nke nchaji na-adịru nwa oge nke ọkwa abụọ ahụ, ebe ụgwọ ọzọ dị mma (na-adịghị mma) na-abawanye (na-ebelata) ike njide nke steeti eletrọnịkị. Rịba ama na mgbago elu nke WS2 valence band bụ maka akara mgbapụta mgbapụta ama ama na mpaghara nke igbe ojii akara na Fig. 1C.
Gbanwee n'ọkwa kacha elu nke WS2 valence band (A) na graphene π-band (B) dị ka ọrụ nke igbu oge nfuli-nyocha yana ihe nrịbama (ahịrị dị oke). Ogologo ndụ nke mgbanwe WS2 na (A) bụ 1.2 ± 0.1 ps. Ogologo ndụ nke mgbanwe graphene na (B) bụ 1.7 ± 0.3 ps.
Na-esote, anyị na-ejikọta mgbaàmà mgbapụta mgbapụta n'elu ebe ndị a na-egosi na igbe ndị na-acha agba na Fig 1C ma na-eme atụmatụ ọnụ ọgụgụ ndị na-esi na ya pụta dị ka ọrụ nke mgbapụta mgbapụta na-egbu oge na 3. Curve 1 na Fig. foto obi ụtọ na-ebu nso na ala nke conduction band nke WS2 oyi akwa na a ndụ nke 1.1 ± 0.1 ps nwetara site na exponential dabara ka. data (lee ihe mgbakwunye mgbakwunye).
Nchọpụta mgbapụta mgbapụta dị ka ọrụ nke igbu oge enwetara site na ijikọta fotocurrent n'elu ebe egosipụtara site na igbe dị na Fig. 1C. Ahịrị gbara ọkpụrụkpụ dabara adaba na data ahụ. Curve (1) Ọnụọgụ ndị na-ebu oge na-ebugharị na band conduction nke WS2. Curve (2) Mgbama mgbapụta mgbapụta nke π-band nke graphene n'elu ikike kemịkalụ nha nhata. Curve (3) Mgbama mgbapụta mgbapụta nke π-band nke graphene n'okpuru ikike kemịkalụ nha nhata. Curve (4) Mgbama nyocha mgbapụta net na valence band nke WS2. A na-achọta oge ndụ dị ka 1.2 ± 0.1 ps na (1), 180 ± 20 fs (uru) na ~ 2 ps (ọnwụ) na (2), na 1.8 ± 0.2 ps na (3).
Na ntụgharị 2 na 3 nke Fig. 3, anyị na-egosi mgbaàmà mgbapụta mgbapụta nke graphene π-band. Anyị na-achọpụta na uru nke electrons n'elu ike nha nha (curve 2 na Fig. 3) nwere ogologo ndụ dị mkpụmkpụ (180 ± 20 fs) ma e jiri ya tụnyere ọnwụ nke electrons n'okpuru ikike kemịkalụ nha (1.8 ± 0.2 ps na curve 3). Foto 3). Ọzọkwa, a na-achọta uru mbụ nke foto ugbu a na curve 2 nke Fig 3 ka ọ ghọọ mfu na t = 400 fs na ndụ nke ~ 2 ps. Achọpụtara asymmetry n'etiti uru na ọnwụ na-anọghị na mgbama mgbapụta mgbapụta nke monolayer graphene ekpughere (lee fig S5 na Ngwa mgbakwunye), na-egosi na asymmetry bụ nsonaazụ nke njikọta interlayer na WS2/graphene heterostructure. Nleba anya nke uru na-adịru nwa oge na ọnwụ dị ogologo n'elu na n'okpuru ikike kemịkalụ nha nha, n'otu n'otu, na-egosi na a na-ewepụ electrons nke ọma na oyi akwa graphene n'elu fotoexcitation nke heterostructure. N'ihi ya, graphene oyi akwa na-aghọ nke ọma ebubo, nke na-ekwekọ na-abawanye na ike njikọ nke π-band dị na fig. 2B. Mbelata nke π-band na-ewepụ ọdụdụ ike dị elu nke nha nha Fermi-Dirac site n'elu ikike kemịkalụ nha nha, nke na-akọwa akụkụ nke mgbanwe nke akara ngosi nke mgbapụta mgbapụta na curve 2 nke Fig. 3. Anyị ga- gosi n'okpuru na mmetụta a na-abawanye site na mfu nke eletrọn na π-band.
Nke a dịruru ná njọ na-akwado site net mgbapụta-probe mgbama nke WS2 valence band na curve 4 nke Fig. 3. E nwetara data ndị a site na ijikọta ọnụ ọgụgụ n'elu ebe nyere igbe ojii na Fig. 1B nke na-ejide electrons photoemitted si. valence band na oge mgbapụta-nyocha ọ bụla. N'ime ogwe mperi mperi nnwale ahụ, anyị ahụghị ihe ngosi maka ọnụnọ oghere dị na band valence nke WS2 maka igbu oge mgbapụta ọ bụla. Nke a na-egosi na, mgbe photoexcitation gasịrị, oghere ndị a na-ejupụta ngwa ngwa n'ogologo oge dị mkpirikpi ma e jiri ya tụnyere mkpebi oge anyị.
Iji nye ihe akaebe ikpeazụ maka echiche anyị nke nkewa ụgwọ ultrafast na WS2/graphene heterostructure, anyị na-ekpebi ọnụọgụ nke oghere agafere na oyi akwa graphene dị ka akọwara n'ụzọ zuru ezu na Ngwa mgbakwunye. Na nkenke, nkesa eletrọnịkị na-agafe agafe nke π-band dabara na nkesa Fermi-Dirac. A na-agbakọ ọnụ ọgụgụ oghere site na ụkpụrụ arụpụtara maka ike kemịkalụ na-agafe agafe na okpomọkụ eletrọnịkị. E gosipụtara nsonaazụ ya na Fig. 4. Anyị na-achọpụta na ọnụ ọgụgụ zuru ezu nke ~ 5 × 1012 oghere / cm2 na-ebufe site na WS2 gaa na graphene na oge ndụ nke 1.5 ± 0.2 ps.
Mgbanwe nke ọnụ ọgụgụ oghere dị na π-band dị ka ọrụ nke mgbapụta-nyocha igbu oge yana ihe dị mma na-enye ndụ nke 1.5 ± 0.2 ps.
Site na nchoputa na fig. 2 ruo 4, foto microscopic na-esonụ maka nnyefe ego ultrafast na WS2 / graphene heterostructure na-apụta (Fig 5). Photoexcitation nke WS2/graphene heterostructure na 2 eV na-ejupụta A-exciton na WS2 (Fig. 5A). Ihe mkpali eletrọnịkị agbakwunyere n'ofe ebe Dirac dị na graphene yana n'etiti WS2 na band graphene nwere ike ike mana ọ naghị arụ ọrụ nke ọma. Oghere foto obi ụtọ dị na valence band nke WS2 na-ejupụta site na electrons sitere na graphene π-band na oge dị mkpirikpi ma e jiri ya tụnyere mkpebi oge anyị (Fig 5A). Eletrọn na-ekpo ọkụ na-ekpo ọkụ na eriri conduction nke WS2 nwere ndụ nke ~ 1 ps (Fig 5B). Agbanyeghị, ọ na-ewe ~ 2 ps iji mejupụta oghere dị na graphene π-band (Fig 5B). Nke a na-egosi na, ewezuga mbufe elektrọn ozugbo n'etiti band conduction WS2 na graphene π-band, ụzọ ezumike ndị ọzọ-ikekwe site na steeti ntụpọ (26)—kwesịrị ka a tụle ya ka ọ ghọta ike zuru oke.
(A) Photoexcitation na resonance na WS2 A-exciton na 2 eV na-etinye electrons n'ime band conduction nke WS2. Oghere ndị kwekọrọ na valence band nke WS2 bụ ndị eletrọn na-ejupụta ozugbo site na graphene π-band. (B) Ndị na-ebu foto nwere obi ụtọ na band conduction nke WS2 nwere ogologo ndụ nke ~ 1 ps. Oghere dị na graphene π-band na-ebi maka ~ 2ps, na-egosi mkpa ọwa mgbasa ozi ndị ọzọ na-egosi site na akụ gbajiri agbaji. Ahịrị ndị nwere agba ojii dị na (A) na (B) na-egosi mgbanwe ngbanwe na mgbanwe na ike kemịkal. (C) Na steeti na-agafe agafe, a na-ebo oyi akwa WS2 n'ụzọ na-adịghị mma ebe a na-ebubo oyi akwa graphene nke ọma. Maka mkpali ahọpụtara nke nwere ọkụ gbara okirikiri, eletrọn na-ese foto na WS2 na oghere ndị kwekọrọ na graphene ka a na-atụ anya na ọ ga-egosi polarization dị iche.
Na ọnọdụ na-agafe agafe, electrons fotoexcited na-ebi na band conduction nke WS2 ebe oghere foto dị na π-band nke graphene (Fig. 5C). Nke a pụtara na WS2 oyi akwa na-adịghị mma na-graphene oyi akwa bụ nke ọma ebubo. Nke a na-akọwa maka mgbanwe kachasị elu nke na-agafe agafe (Fig 2), asymmetry nke graphene pump-probe signal (curves 2 na 3 of Fig. 3), enweghị oghere na valence band nke WS2 (curve 4 Fig. 3). , yana oghere ndị ọzọ na graphene π-band (Fig 4). Oge ndụ nke steeti a kewapụrụ ụgwọ bụ ~ 1 ps (curve 1 Fig. 3).
A hụla steeti ndị na-agafe agafe n'ụdị ụgwọ dị iche iche n'ụdị heterostructures van der Waals nke emere site na semiconductor oghere nwere oghere nwere ụdị II band alignment na bandgap staggered (27-32). Mgbe photoexcitation gasịrị, a chọtara electrons na oghere ka ọ na-aga ngwa ngwa na ala nke band conduction na n'elu nke valence band, nke dị n'ụdị dị iche iche nke heterostructure (27-32).
N'ihe banyere WS2/graphene heterostructure anyị, ebe kacha mma maka elektrọn na oghere dị na ọkwa Fermi na oyi akwa graphene dara. Ya mere, mmadụ ga-atụ anya na ma electrons na oghere na-ebufe ngwa ngwa na graphene π-band. Agbanyeghị, nha anyị na-egosi n'ụzọ doro anya na mbufe oghere (<200 fs) na-arụ ọrụ nke ọma karịa nnyefe elektrọn (~ 1 ps). Anyị na-ekwu na nke a bụ njikọ ike ike nke WS2 na band graphene dị ka ekpughere na Fig. 1A nke na-enye ọnụ ọgụgụ ka ukwuu nke steeti ikpeazụ dị maka mbufe oghere ma e jiri ya tụnyere nnyefe elektrọn dị ka echere na nso nso a (14, 15). N'okwu dị ugbu a, na-eche na 2 eV WS2 bandgap, graphene Dirac point na ike kemịkalụ nha dị ~ 0.5 na ~ 0.2 eV n'elu etiti nke bandgap WS2, n'otu n'otu, na-agbaji akara ngosi electron-hole. Anyị na-achọpụta na ọnụ ọgụgụ nke steeti ikpeazụ dị maka ịnyefe oghere bụ ~ 6 ugboro ka ukwuu maka nnyefe eletrọn (lee ihe mgbakwunye), nke mere a na-atụ anya na nnyefe oghere ga-adị ngwa ngwa karịa nnyefe electron.
Foto pere mpe zuru oke nke mbufe chaja asymmetric ultrafast hụrụ kwesịrị, n'agbanyeghị, tụlekwaa nchikota dị n'etiti orbitals nke mejupụtara ọrụ ebili mmiri A-exciton na WS2 na graphene π-band, n'otu n'otu, eletrọn-electron dị iche iche na mgbasa elektrọn-phonon. Ọwa gụnyere ihe mgbochi ndị a na-etinye site na ume, ume, spine, na nchekwa pseudospin, mmetụta nke oscillations plasma. (33), yana ọrụ nke mkpali mgbakasị ahụ enwere ike ịmegharị phonon oscillation nke nwere ike ịgbazinye nnyefe ụgwọ (34, 35). Ọzọkwa, mmadụ nwere ike ịkọwa ma ọnọdụ mbufe ụgwọ a hụrụ na-agụnye exciton mbufe ụgwọ ma ọ bụ oghere eletrọn n'efu (lee Ngwa mgbakwunye). Nnyocha ndị ọzọ gbasara usoro ọmụmụ nke gafere oke akwụkwọ a chọrọ iji dokwuo anya okwu ndị a.
Na nchịkọta, anyị ejirila tr-ARPES mụọ ultrafast interlayer charge transfer na epitaxial WS2/graphene heterostructure. Anyị chọpụtara na, mgbe ọ na-enwe obi ụtọ na resonance na A-exciton nke WS2 na 2 eV, oghere foto ahụ na-ebufe ngwa ngwa n'ime oyi akwa graphene ka electrons photoexcited na-anọgide na oyi akwa WS2. Anyị kwuru na nke a bụ na ọnụ ọgụgụ nke steeti ikpeazụ dị maka mbufe oghere dị ukwuu karịa maka mbufe elektrọn. Achọpụtara oge ndụ nke ụgwọ-na-adịru nwa oge dị ~ 1 ps. N'ịgbakọta na mkpali ngwa anya nke a na-ahọrọ na-eji ọkụ nwere okirikiri (22-25), nnyefe ultrafast a hụrụ nwere ike iso ya na mbufe ntụgharị. N'okwu a, enwere ike iji WS2/graphene heterostructure nyochara maka ịgbanye ntụtụ anya nke ọma n'ime graphene na-ebute ngwa ngwa optospintronic.
A na-etolite ihe nlele graphene na semiconducting azụmahịa 6H-SiC(0001) wafers sitere na SiCrystal GmbH. N-doped wafers nọ na-axis nwere mperi n'okpuru 0.5°. Mkpụrụ SiC bụ hydrogen-etched iji wepụ ncha ma nweta mbara ala dị larịị mgbe niile. A na-esezigharị elu ahụ dị ọcha na nke dị larịị nke Si-kwụsịchara site n'iwepụ ihe nlele ahụ na ikuku Ar na 1300 Celsius C maka nkeji 8 (36). N'ụzọ dị otú a, anyị nwetara otu carbon oyi akwa ebe ọ bụla nke atọ carbon atom kpụrụ a covalent njikọ na SiC substrate (37). A tụgharịrị oyi akwa a ka ọ bụrụ sp2-hybridized quasi free-standing hole-doped graphene site na hydrogen intercalation (38). A na-akpọ ihe atụ ndị a dị ka graphene / H-SiC (0001). Emere usoro a niile n'ime ụlọ uto Black Magic azụmahịa sitere na Aixtron. A na-eme uto WS2 n'ụdị reactor na-ekpo ọkụ na-ekpo ọkụ site na ntinye ikuku kemịkalụ dị ala (39, 40) na-eji WO3 na S powders nwere oke 1: 100 dị ka ndị na-ebute ụzọ. A na-edobe ntụ ntụ WO3 na S na 900 na 200 Celsius, n'otu n'otu. A na-etinye ntụ ntụ WO3 nso na mkpụrụ. A na-eji argon mee ihe dị ka gas na-ebu ibu nke nwere 8 sccm. Edebere nrụgide dị na reactor na 0,5 mbar. E ji ihe nlele eletrọn anya nke abụọ mara, microscope atomic force microscopy, Raman, na fotoluminescence spectroscopy, yana diffraction eletrọn dị ala. Ntụle ndị a kpughere ngalaba WS2 otu-crystalline abụọ dị iche iche ebe ma ΓK- ma ọ bụ ΓK'-ntụziaka dabara na ntụzịaka ΓK nke oyi akwa graphene. Ogologo akụkụ ngalaba dịgasị iche n'etiti 300 na 700 nm, na mkpokọta WS2 mkpuchi bụ ihe ruru ~40%, dabara maka nyocha ARPES.
Emere nnwale ARPES static site na iji onye nyocha hemispherical (SPECS PHOIBOS 150) na-eji sistemu ngwaọrụ ejikọtara ụgwọ maka nchọpụta akụkụ abụọ nke ike elektrọn na ike. Unpolarized, monochromatic He Iα radieshon (21.2 eV) nke elu-flux Isi iyi mwepu (VG Scienta VUV5000) ka ejiri mee nnwale fotoemission niile. Mkpebi ike na angular na nnwale anyị dị mma karịa 30 meV na 0.3 Celsius (dakọtara na 0.01 Å-1), n'otu n'otu. Emere nnwale niile na okpomọkụ ụlọ. ARPES bụ usoro na-enwe mmetụta nke ukwuu. Iji chụpụ fotoelectrons site na ma WS2 na oyi akwa graphene, ejiri ihe nlele nwere mkpuchi WS2 ezughi oke nke ~40%.
Ntọala tr-ARPES dabere na 1-kHz Titanium:Sapphire amplifier (Coherent Legend Elite Duo). A na-eji 2 mJ nke mmepụta ike mee ihe maka ọgbọ harmonics dị elu na argon. Ìhè ultraviolet na-esi na ya pụta gafere site na monochromator grating na-emepụta 100-fs probe pulses na ike 26-eV photon. 8mJ nke ike mmepụta ampilifaya ezigara n'ime ngwa ngwa parametric ngwa anya (HE-TOPAS sitere na ntụgharị ọkụ). Oghere mgbama dị na 1-eV photon energy bụ ugboro ugboro okpukpu abụọ na kristal beta barium borate iji nweta pulses mgbapụta 2-eV. Ejiri ihe nyocha nke hemispherical (SPECS PHOIBOS 100) mee nha tr-ARPES. Ike zuru oke na mkpebi nke nwa oge bụ 240 meV na 200fs, n'otu n'otu.
Ihe mgbakwunye maka akụkọ a dị na http://advances.sciencemag.org/cgi/content/full/6/20/eaay0761/DC1
Nke a bụ edemede oghere mepere emepe ekesara n'okpuru usoro ikike nke Creative Commons Attribution-NonCommercial, nke na-enye ohere iji, nkesa, na mmeputakwa n'ụdị ọ bụla, ma ọ bụrụhaala na nsonaazụ ya abụghị maka uru azụmahịa ma ọ bụrụhaala na ọrụ mbụ ahụ dabara nke ọma. kwuru.
IHE: Anyị na-arịọ naanị adreesị ozi-e gị ka onye ị na-atụ aro ibe ya mara na ị chọrọ ka ha hụ ya, na ọ bụghị ozi junk. Anyị anaghị ejide adreesị ozi-e ọ bụla.
Ajụjụ a bụ maka ịnwale ma ị bụ onye ọbịa mmadụ ma ọ bụ na ị bụghị yana igbochi ntinye spam na-akpaghị aka.
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 ụgwọ ultrafast na WS2/graphene heterostructure nwere ike na-enye ike ịgbanye ntụtụ anya 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 ụgwọ ultrafast na WS2/graphene heterostructure nwere ike na-enye ike ịgbanye ntụtụ anya n'ime graphene.
© 2020 American Association for the Advancement of Science. Ikike niile echekwabara. AAAS bụ onye mmekọ nke HINARI, AGORA, OARE, CHORUS, CLOCKSS, CrossRef na COUNTER. Ọganihu sayensị ISSN 2375-2548.
Oge nzipu: Mee-25-2020