Wonke umuntu uyazi ukuthi amanzi avela ezifundeni ezintathu zokuhlanganisa. Sibeka iketela, futhi amanzi aqala ukubilisa futhi ahwamuke, aphenduke asuka oketshezini abe yigesi. Siyifaka efrijini, futhi iqala ukuphenduka iqhwa, ngaleyo ndlela isuka oketshezini iye esimweni esiqinile. Kodwa-ke, ngaphansi kwezimo ezithile, umhwamuko okhona emoyeni ungadlula ngokushesha esigabeni esiqinile, udlule isigaba soketshezi. Siyazi le nqubo ngomphumela wayo - amaphethini amahle emafasiteleni ngosuku lwasebusika olubandayo. Abathandi bezimoto, lapho bekhuhla ungqimba lweqhwa ku-windshield, bavame ukuveza le nqubo ngokusebenzisa i-epithets engeyona eyesayensi kakhulu, kodwa engokomzwelo kakhulu futhi ecacile. Ngandlela-thile, imininingwane yokwakheka kweqhwa elinezinhlangothi ezimbili yayimbozwe imfihlo iminyaka eminingi. Futhi muva nje, ngokokuqala ngqΓ‘, iqembu lososayensi bomhlaba wonke likwazile ukubona ngeso lengqondo ukwakheka kwe-athomu yeqhwa elinezinhlangothi ezimbili phakathi nokwakheka kwalo. Yiziphi izimfihlo ezifihliwe kule nqubo ebonakalayo ilula, ososayensi bakwazi kanjani ukuzidalula, futhi lokho abakutholile kuwusizo kanjani? Umbiko weqembu locwaningo uzositshela ngalokhu. Hamba.
Isisekelo socwaningo
Uma senza ihaba, cishe zonke izinto ezisizungezile zinezinhlangothi ezintathu. Nokho, uma sicubungula ezinye zazo ngokucophelela, singathola ezinezinhlangothi ezimbili. Uqweqwe lweqhwa olwakha phezu kokuthile luyisibonelo esihle salokhu. Ukuba khona kwezakhiwo ezinjalo akuyona imfihlo emphakathini wesayensi, ngoba ziye zahlaziywa izikhathi eziningi. Kodwa inkinga ukuthi kunzima kakhulu ukubona ngeso lengqondo izakhiwo ze-metastable noma eziphakathi ezihilelekile ekwakhiweni kweqhwa le-2D. Lokhu kungenxa yezinkinga ze-banal - ubuthakathaka kanye ne-fragility yezakhiwo ezifundwayo.
Ngenhlanhla, izindlela zesimanje zokuskena zivumela amasampula ukuba ahlaziywe ngomthelela omncane, okuvumela ukuthi idatha ephezulu itholwe ngesikhathi esifushane, ngenxa yezizathu ezingenhla. Kulolu cwaningo, ososayensi basebenzise i-microscopy yamandla e-athomu engathinteki, nesihloko senaliti yesibonakhulu esihlanganiswe ne-carbon monoxide (CO). Inhlanganisela yalawa mathuluzi okuskena yenza kube nokwenzeka ukuthola izithombe zesikhathi sangempela zezakhiwo ezinqenqemeni zeqhwa elinezinhlangothi ezimbili ze-bilayer elinezinhlangothi ezine ezitshalwe endaweni yegolide (Au).
I-Microscopy ibonise ukuthi ngesikhathi kwakhiwa iqhwa elinezinhlangothi ezimbili, izinhlobo ezimbili zamaphethelo (izingxenye ezixhuma ama-vertices amabili epholigoni) zihlangana ngesikhathi esisodwa esakhiweni salo: i-zigzag (zigzag) futhi okumise okwesihlalo (isihlalo semoto).
Isihlalo sengalo (kwesokunxele) kanye namaphethelo amazigzag (kwesokudla) kusetshenziswa i-graphene njengesibonelo.
Kulesi sigaba, amasampula aqandiswe ngokushesha, okuvumela ukuthi ukwakheka kwe-athomu kuhlolwe ngokuningiliziwe. Ukumodela kwenziwa futhi, imiphumela ehambisana kakhulu nemiphumela yokubuka.
Kutholakale ukuthi uma kwenzeka ukwakheka kwezimbambo ze-zigzag, i-molecule yamanzi eyengeziwe yengezwa emaphethelweni akhona, futhi yonke inqubo ilawulwa indlela yokubopha ibhuloho. Kodwa endabeni yokwakhiwa kwezimbambo zezihlalo zengalo, awekho ama-molecule engeziwe atholakele, aphikisana kakhulu nemibono yendabuko mayelana nokukhula kweqhwa elinezingqimba ezimbili zeqhwa kanye nezinto ezinezinhlangothi ezinezinhlangothi ezine ngokujwayelekile.
Kungani ososayensi bakhethe isibonakhulu esingathinteki se-athomu yamandla ukuze bakubhekisise kunesibonakhulu esithwebulayo (STM) noma isibonakhulu se-electron yokudlulisa (TEM)? Njengoba sesivele sazi, ukukhetha kuhlobene nobunzima bokufunda izakhiwo ezihlala isikhathi esifushane nezintekenteke zeqhwa elinezinhlangothi ezimbili. I-STM ike yasetshenziselwa ukutadisha amaqhwa e-2D atshalwe ezindaweni ezihlukahlukene, kodwa lolu hlobo lwe-microscope aluzweli endaweni ye-nuclei, futhi ithiphu layo lingabangela amaphutha ezithombeni. I-TEM, ngokuphambene, ikhombisa ngokuphelele ukwakheka kwe-athomu yezimbambo. Nokho, ukuthola izithombe zekhwalithi ephezulu kudinga ama-electron anamandla aphezulu, angashintsha kalula noma acekele phansi uhlaka lwesakhiwo sezinto ze-XNUMXD eziboshwe ngokuhlanganyela, ingasaphathwa eyonqenqema ebophene kakhudlwana kuqhwa le-XNUMXD.
Isibonakhulu samandla e-athomu asinabo ububi obunjalo, futhi ithiphu ehlanganiswe ne-CO ivumela ukufundwa kwamanzi ahlanganayo anethonya elincane kuma-molecule amanzi.
Imiphumela yocwaningo
Isithombe #1
Iqhwa elinezinhlangothi ezimbili lalitshalwe endaweni ye-Au(111) ngezinga lokushisa elingaba ngu-120 K, futhi ukujiya kwalo kwakungu-2.5 Γ (I-1).
Izithombe ze-STM zeqhwa (1c) kanye nesithombe esihambisanayo esisheshayo se-Fourier (okufakwe ngaphakathi I-1) bonisa ukwakheka kwe-hexagonal ehlelwe kahle ene-periodicity ye-Au(111)-β3 x β3-30Β°. Nakuba inethiwekhi yeselula exhunywe ku-H yeqhwa le-2D ibonakala esithombeni se-STM, i-topology enemininingwane yezakhiwo ezinqenqemeni kunzima ukunquma. Ngesikhathi esifanayo, i-AFM ene-frequency shift (Ξf) yendawo yesampula efanayo inikeze izithombe ezingcono (1d), okwenza kube nokwenzeka ukubona ngeso lengqondo izingxenye zesakhiwo ezimise okwesihlalo nezigzag. Ubude obuphelele bazo zombili izinhlobo buyaqhathaniswa, kodwa ubude obumaphakathi bobambo olwandulelayo bude kancane (1b). Izimbambo ze-Zigzag zingakhula zifike ku-60 Γ ubude, kodwa ezimise okwesihlalo zimbozwa amaphutha ngesikhathi sokubunjwa, okunciphisa ubude bazo obukhulu bufinyelele ku-10-30 Γ .
Okulandelayo, ukuthwebula okuhlelekile kwe-AFM kwenziwa ezindaweni eziphakeme yenaliti (I-2).
Isithombe #2
Ekuphakameni okuphezulu kwethiphu, lapho isignali ye-AFM ibuswa amandla e-electrostatic esezingeni eliphezulu, amasethi amabili angu-β3 x β3 ama-sublattice angaphansi kweqhwa elinezinhlangothi ezimbili e-bilayer ahlonziwe, elinye lawo liboniswa ku- I-2 (kwesokunxele).
Ezindaweni eziphakeme yenaliti eziphansi, izakhi ezikhanyayo zale subarray ziqala ukukhombisa isiqondiso, kanti enye i-subarray iphenduka into emise okwe-V (2a, maphakathi).
Ebuncaneni obuncane benaliti, i-AFM yembula isakhiwo sezinyosi esinemigqa ecacile exhumanisa ama-sublattice amabili, okusikhumbuza ama-H-bond (2a, kwesokudla).
Izibalo zethiyori esebenzayo yokuminyana zibonisa ukuthi iqhwa elinezinhlangothi ezimbili elikhule endaweni ye-Au(111) lihambisana nesakhiwo seqhwa esinezingqimba ezimbili (2s), ehlanganisa izingqimba ezimbili zamanzi ezinama-hexagonal amabili. Ama-hexagons amashidi amabili ahlanganiswe, futhi i-engeli phakathi kwama-molecule amanzi endizeni ingu-120 Β°.
Kusendlalelo ngasinye samanzi, ingxenye yama- molecule amanzi ilele ivundlile (ihambisana ne-substrate) kanti enye ilala ibheke phezulu (i-perpendicular to the substrate), enye i-O-H ibheke phezulu noma phansi. Amanzi alele aqondile kungqimba olulodwa anikela ngebhondi engu-H emanzini avundlile kwenye isendlalelo, okuholela ekwakhiweni okugcwele okumise okuka-H.
Ukulingisa kwe-AFM kusetshenziswa ithiphu ye-quadrupole (dz 2) (2b) okusekelwe kumodeli engenhla kuvumelana kahle nemiphumela yokuhlola (2a). Ngeshwa, ukuphakama okufanayo kwamanzi avundlile naqondile kwenza ukukhonjwa kwawo kube nzima ngesikhathi sokuthwebula kwe-STM. Kodwa-ke, lapho usebenzisa i-microscopy yamandla e-athomu, ama-molecule azo zombili izinhlobo zamanzi ahlukaniseka ngokucacile (2a ΠΈ 2b kwesokudla) ngenxa yokuthi amandla e-electrostatic azwela kakhulu ukuma kwama-molecule amanzi.
Kuphinde kwaba nokwenzeka ukuthi kuqhutshekwe kunqunywe ukuqondiswa kwe-OH kwamanzi avundlile naqondile ngokusebenzisana phakathi kwamandla kagesi e-electrostatic kanye namandla aphikisayo ka-Pauli, njengoba kuboniswa imigqa ebomvu ku. I-2 ΠΈ 2b (phakathi).
Isithombe #3
Ezithombeni I-3 ΠΈ 3b (Isiteji 1) sibonisa izithombe ze-AFM ezikhulisiwe zama-zigzag nama-armchair fins, ngokulandelana. Kutholakale ukuthi umkhawulo we-zigzag ukhula ngenkathi ugcina isakhiwo sawo sokuqala, futhi ngokukhula konqenqema olunesimo sesihlalo, umkhawulo ubuyiselwa esakhiweni se-periodic samasongo angu-5756, i.e. lapho ukwakheka kwezimbambo kuphindaphinda i-pentagon yokulandelana - i-heptagon - i-pentagon - i-hexagon.
Izibalo zethiyori esebenza ngokuminyana zibonisa ukuthi i-zigzag fin engakhiwe kabusha kanye ne-chair 5756 yizona ezime kakhulu. Unqenqema lwe-5756 lwakhiwe ngenxa yemiphumela ehlanganisiwe enciphisa inani lamabhondi e-hydrogen angagcwele futhi inciphise amandla obunzima.
Ososayensi bayakhumbula ukuthi izindiza eziyisisekelo zeqhwa elinezinhlangothi ezine ngokuvamile ziphelela ezimbanjeni ezimazombezombe, futhi izimbambo ezimise okwesihlalo azikho ngenxa yokuminyana okuphezulu kwe-unsaturated hydrogen bond. Kodwa-ke, ezinhlelweni ezincane noma lapho isikhala sincane, amaphiko esihlalo anganciphisa amandla azo ngokuklama kabusha okufanele.
Njengoba kushiwo ngaphambili, lapho ukukhula kweqhwa ku-120 K kumisiwe, isampula lapholiswa ngokushesha laya ku-5 K ukuze kuzanywe ukufriza izakhiwo zonqenqema ze-metastable noma ezishintshayo futhi kuqinisekiswe ukuphila okuyisampula okude kocwaningo olunemininingwane kusetshenziswa i-STM ne-AFM. Kuphinde kwaba nokwenzeka ukwakhiwa kabusha kwenqubo yokukhula kweqhwa elinezinhlangothi ezimbili (isithombe No. 3) sibonga ithiphu le-CO-functionalized microscope, elenze kwaba nokwenzeka ukuhlonza izakhiwo ze-metastable nezishintshayo.
Endabeni yezimbambo ze-zigzag, ama-pentagon ngamanye ngezinye izikhathi ayetholakala enamathele ezimbanjeni eziqondile. Bangakwazi umugqa ngokulandelana, benze uhlu olune-periodicity engu-2 x iqhwa (iqhwa yi-lattice engaguquki yeqhwa elinezinhlangothi ezimbili). Lokhu kubheka kungase kubonise ukuthi ukukhula kwemiphetho ye-zigzag kuqalwa ukwakheka kwe-periodic array of pentagons (I-3, isinyathelo 1-3), okubandakanya ukwengeza amapheya amabili amanzi epentagon (imicibisholo ebomvu).
Okulandelayo, uhlu lwama-pentagon luxhunywe ukwakha isakhiwo esifana ne-56665 (I-3, isigaba 4), bese ibuyisela ukubukeka kwamazombezombe kwasekuqaleni ngokungeza umhwamuko omningi wamanzi.
Ngemiphetho emise okwesihlalo isimo siphambene - awekho ama-pentagons, kodwa kunalokho izikhala ezimfushane ezifana ne-5656 onqenqemeni zivame ukubonwa. Ubude be-fin engu-5656 bufishane kakhulu kunobuka-5756. Lokhu kungenzeka ngoba i-5656 fin igcizelelwe kakhulu futhi ayizinzile kangako kune-5756. Ukuqala nge-chair fin engu-5756, izindandatho ezingama-575 ziguqulelwa endaweni zaba izindandatho ezingama-656 ngokungeza amabili. umhwamuko wamanzi (3b, isigaba 2). Okulandelayo, izindandatho ezingu-656 zikhulela ohlangothini oluphambene, zakhe unqenqema lohlobo lwe-5656 (3b, isigaba 3), kodwa ngobude obulinganiselwe ngenxa yokuqoqwa kwamandla okuguqula.
Uma ipheya eyodwa yamanzi yengezwa ku-hexagon ye-5656 fin, ukuguqulwa kungenziwa buthaka kancane, futhi lokhu kuzophinde kuholele ekwakhekeni kwe-5756 fin (3b, isigaba 4).
Imiphumela engenhla iyinkomba kakhulu, kodwa kwanqunywa ukuyisekela ngedatha eyengeziwe etholwe ekubalweni kwe-molecular dynamics yomhwamuko wamanzi endaweni ye-Au (111).
Kutholwe ukuthi iziqhingi zeqhwa ezinezingqimba ezimbili ze-XNUMXD zakhiwe ngempumelelo futhi zingaphazanyiswa phezulu, okuhambisana nokuqaphela kwethu kokuhlola.
Isithombe #4
Esithombeni I-4 Indlela yokwakheka okuhlangene kwamabhuloho ezimbanjeni ezimazombezombe iboniswa isinyathelo ngesinyathelo.
Ngezansi kukhona izinto zemidiya kulolu cwaningo ezinencazelo.
Izinto zemidiya No. 1
Kuyaphawuleka ukuthi i-pentagon eyodwa exhunywe onqenqemeni lwe-zigzag ayikwazi ukusebenza njengesikhungo se-nucleation sendawo ukukhuthaza ukukhula.
Izinto zemidiya No. 2
Esikhundleni salokho, inethiwekhi yezikhathi ezithile kodwa engaxhumekile yama-pentagon ekuqaleni yakha onqenqemeni lwama-zigzag, futhi ama-molecule amanzi angenayo alandelayo ngokuhlanganyela azama ukuxhuma lawa ma-pentagon, okuholela ekwakhekeni kwesakhiwo seketango lohlobo lwe-565. Ngeshwa, isakhiwo esinjalo asizange sibonwe ngesikhathi ukuqaphela okungokoqobo, okuchaza ubude bayo obufushane kakhulu.
Izinto zemidiya No. 3 kanye No. 4
Ukwengezwa kwepheya elilodwa lamanzi kuxhuma isakhiwo sohlobo lwe-565 kanye ne-pentagon eseduze, okuholela ekwakhekeni kwesakhiwo sohlobo lwe-5666.
Isakhiwo sohlobo lwe-5666 sikhula sibheke eceleni ukuze sakhe ukwakheka kohlobo lwe-56665 futhi ekugcineni sithuthuke sibe i-lattice ene-hexagonal exhunywe ngokugcwele.
Izinto zemidiya No. 5 kanye No. 6
Esithombeni 4b ukukhula kuboniswa endabeni yombambo we-armchair. Ukuguqulwa kusuka kumasongo ohlobo lwe-575 ukuze kuthayiphe izindandatho ezingama-656 kuqala kusuka kungqimba olungezansi, kwakha isakhiwo esiyinhlanganisela esingu-575/656 esingakwazi ukuhlukaniswa nohlobo lwe-5756 fin ekuhlolweni, njengoba kuphela ungqimba olungaphezulu lweqhwa elinezingqimba ezimbili olungathathwa isithombe. ngesikhathi sokuhlolwa.
Izinto zemidiya No. 7
Ibhuloho eliwumphumela 656 liba isikhungo se-nucleation sokukhula kombambo we-5656.
Izinto zemidiya No. 8
Ukwengeza i-molecule yamanzi eyodwa onqenqemeni lwe-5656 kuphumela kusakhiwo se-molecule engabhangqiwe ehamba kakhulu.
Izinto zemidiya No. 9
Amabili alawa mamolekyuli amanzi angabhangqwa kamuva angahlangana abe isakhiwo esine-heptagonal ezinzile, aqedele ukuguqulwa kusuka ku-5656 kuya ku-5756.
Ukuze uthole ulwazi oluningiliziwe ngama-nuances ocwaningo, ngincoma ukubheka .
Epilogue
Isiphetho esiyinhloko salolu cwaningo siwukuthi ukuziphatha okubhekwe kwezakhiwo ngesikhathi sokukhula kungase kuvame kuzo zonke izinhlobo zeqhwa elinezinhlangothi ezimbili. Iqhwa le-Bilayer elinama-hexagonal amafomu ezindaweni ezihlukahlukene ze-hydrophobic nangaphansi kwezimo zokuvalelwa kwe-hydrophobic, ngakho-ke lingabhekwa njenge-crystal ye-2D ehlukile (i-2D ice I), ukwakheka kwayo okungenandaba nesakhiwo esingaphansi se-substrate.
Ososayensi basho ngobuqotho ukuthi indlela yabo yokuthwebula ayikafaneleki ukusebenza neqhwa elinezinhlangothi ezintathu, kodwa imiphumela yokutadisha iqhwa elinezinhlangothi ezimbili ingasebenza njengesisekelo sokuchaza inqubo yokwakheka kwesihlobo salo se-volumetric. Ngamanye amazwi, ukuqonda ukuthi izakhiwo ezinezinhlangothi ezimbili zakha kanjani kuyisisekelo esibalulekile sokufunda ezinezinhlangothi ezintathu. Kungenxa yale njongo ukuthi abacwaningi bahlela ukuthuthukisa indlela yabo esikhathini esizayo.
Siyabonga ngokufunda, hlalani nelukuluku futhi nibe neviki elihle bafana. π
Ezinye izikhangiso π
Siyabonga ngokuhlala nathi. Uyazithanda izindatshana zethu? Ufuna ukubona okuqukethwe okuthakaselayo okwengeziwe? Sisekele ngokufaka i-oda noma ngokuncoma kubangani, , i-analogue ehlukile yamaseva ezinga lokungena, esungulwe yithi ngenxa yakho: (itholakala nge-RAID1 kanye ne-RAID10, kufika kuma-cores angu-24 kuze kufike ku-40GB DDR4).
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Source: www.habr.com