Application of angstorm level resolution in nanotechnology (150028)















Applctns f ngstrm Lvl Rslutn n Nn Tchnlgy



1. ntrductn


Lkng bck, th bgnnngs f mcrscpy dt bck t th tm f Rbrt Hk whr h usd pc f glss lns fr mgnfy f hs spcmn by bndng th ry f lght. t ws vn prt f hs bk Mcrgrph nd th frst ptcl mcrscp ws dvlpd. Th dvlpmnt f th hgh pwrd mcrscps ws du t mns nd t furthr mgnfy nd s wht ur nkd y cn prcv. Mgnfyng n bjct s lmtd t bng bl t dstngush n pnt frm th thr, smpl dfntn f rslutn. Th dstnc f tw pnts f whch bng sprt dstnct ntts s th lmt f rslutn [1]. Th dvlpmnt ws bsd n th xhustd ptntl f th tls. Hstrclly, th prblms wth rslutn s wll s mn functn f th tl wr th mn fctr fr th dvlpmnt f nw mcrscp. Rslutn hd bn th frmst cncrn fr th dvlpmnt f th hgh pwrd mcrscp up t th lctrn mcrscp lvl. Th ptcl mcrscp srvd s th mdl fr th dsgn nd cncpt f th succdng mcrscps. Th wv ntur f lght ws th mn bckbn f rslutn s t s rltd t wvlngth by th bbs qutn [1]:


qutn 1 [1]


whr d = rslutn

λ = wvlngth f th nrgy surc

n = ndx f rfrctn f th mdum thrugh th nrgy surc trvls

ά = prtur ngl

Gvn ths rltnshp f lght wv nd rslutn, thr surc f llumntn r nrgy ws drvd. Th lctrn mcrscp ws dvlpd usng lctrns cclrtng n th spd f lght [2]. Thy usd lctrns frm sturtd bm t g thrugh lctrmgntc lnss bng bl t rslv ngstrm thck f mtrl [1,2]. Th lctrmgntc lnss srvd t dflct th lctrns thrugh th clumn. Ths cpblty f th lctrn mcrscps md t pssbl t rslv frm th mcrn lvl (thusndth f mtr), nn lvl (mllnth f mtr) t sub ngstrm (lss thn tn mllnth f mtr). Thugh hgh mgnfctns cn b chvd, th M ws lmtd by brrtns du th wv dflctd n th lnss [2]. Tdy, ctupls nd qudrupls r ddd cmpnst fr th sphrcl brrtns. nthr lmttn f lctrn mcrscps, chrmtc brrtn, s bng rslvd wth th TM (Trnsmssn lctrn- brrtn crrctd Mcrscp) prjct f th ntnl lctrn mcrscpy lbs hr n th US. Th hghst rslutn n n lctrn mcrscp tdy s t 0.7 ngstrm.

Mcrscpy plys bg rl n th nntchnlgy rvlutn. ccrdng t M [3], th cntrl chllng n nntchnlgy s dntfctn f nn mtrl synthss nd undrstndng structurs n nn r sub nn mtr lvl. Th mcrscpy tchnqus nbl scntsts t lk nt th structurs s t shp, sz, structur nd rnttn f nn mtrls [3]. Lrnng vsully s ky t bttr undrstndng t nw tchnlgy such s ths. Spcfc pplctns f nn mtrl chrctrztn by mcrscpy wll b dscussd furthr n th ppr.



2. Lmttns f lctrn Mcrscps


lthugh hgh mgnfctns wr chvd n th lctrn mcrscps, blurrnss ccurrd. Ths ws du t th wvs tht wr dflctd s th lctrns trvl dwn th clumn [1,2,4]. Ths wvs wr clld brrtns, sphrcl nd chrmtc brrtn. Th lctrn mcrscp dvlpd n th 16th cntury. n tht tm prd nd ftr, dffrnt typs f lctrn mcrscps wr dvlpd bsd n th dffrnt pplctns. Ths wr th SM (Scnnng lctrn Mcrscp), STM(Scnnng Tunnlng Mcrscp), SPM (Scnnng Prb Mcrscp) nd FM (tmc Frc Mcrscp). Thr ws pnt tht dvlpmnt ws stgnnt. By 1998, th dvlpmnt f brrtn crrctrs ws studd. Th push t dvlp n brrtn fr lctrn mcrscp hd bn ngng snc thn. Th ntnl lctrn mcrscpy lbrtrs n th US r wrkng t slv ths hndrnc n mcrscpy. Nllst [4] numrtd th ky vnts rgrdng brrtn snc th bgnnng f mcrscpy:


Th 10 ky moments n th pth t tmc rslutn [4]:

  • 16th cntury Th dvlpmnt f th cmpund ptcl mcrscp

  • 1873 rnst bb prsnts dtld thry f mg frmtn n th mcrscp

  • 1896 Lrd Rylgh dfns th rslutn lmt fr n ptcl systm by cnsdrng dffrctn f wvs n th lns prtur

  • 1933 Knll nd Rusk nvnt th trnsmssn lctrn mcrscp

  • 1936 tt Schrzr shws tht lctrn lnss r lmtd by ntrnsc sphrcl brrtn

  • 1955 rwn Müllr uss fld n mcrscp t btn th frst mgs f tms

  • 1970 mgs f sngl thllum tms chvd by lbrt Crw nd c-wrkrs usng STM

  • 1970s Rslvng crystl lttcs usng trnsmssn lctrn mcrscp strts t bcm rutn

  • 1982 Bnng nd Rhrr nvnt th STM, whch s cpbl f mgng tms n surfcs; thr scnnng prb mcrscps fllw

  • 1998 nwrds Th dvlpmnt f sphrcl-brrtn-crrctn tchnlgy strts t rvlutnz TM prfrmnc nd brngs but rutn sub-ångström-rslutn mgng


Th d Brgl wvlngth prncpl ( wvlngth s qul t Plnks cnstnt dvdd by mmntum; l = h / p) ds nt nswr th prblm f brrtn. Th lmttn by brrtns ws dcttd ccrdng t Rylgh by dffrctn [4,5]. Nllst xplnd by th qutn[4]:


d= 1.22 λ/θ qutn 2 [4]


whr d = rslvng pwr, λ= wvlngth nd θ = ngl subtndd by th prtur.

Bsd n qutn 2, th M wll rqur prfct lns. Th fcl lngth f n M lns s 2mm, t thn rqurs wvfrnt t b fcusd n prcs dstnc f n qurtr f wvlngth, rund 5 pcmtrs [4]. Ths prfct lns cnnt b prducd wth lctrmgntc lnss f n M. Unlk rgulr glss lns t cn b prfctd by plshng r grndng, lctrmgntc lnss cn nly b cntrl by th prncpl f Mxwll rltns [4]. s xplnd by Βkf [5], ncrsng th cclrtng vltg mprvs rslutn by rducng th lctrn wvlngth by 12 th squr rt f th wvlngth. chvng th ngstrm rslutn wuld stll rqur crrctrs t dcrs brrtns.

Th crrctn tchnlgy s nw vlbl fr th TMs.Th prsnc f ctupls nd qudrpuls dflcts th bm twrds n ptc xs such n Fgur 1.

Th ctupls r ght ltrntng pls f pstv nd ngtv tht dflct th bm hwvr nthr qudrupl-ctupl s rqurd. Ths crrctr srvs t frm "ln crss vr" pnt tht ll th wvs cnvrgs nd thn fnlly gs thrugh th qudrupl t th fcl pln [4,5]. s mntnd n th ppr f Nllst [4], t s mprtnt t hv ll th pls prprly ln up snc t cn stll cus sphrcl brrtn. Th pplctn f ths crrctrs s dpndnt n th vltg th M. chvng sub ngstrm lvl rslutn wuld stll rqur md vltg prtn t rduc th wvlngth [5].





Fgur 1. s th bm gs thrugh th prtur, sm rys r dflctd cusng sphrcl brrtn, (mddl) ctupl ddd t th bm but nt nugh t hv n crssvr s t psss thrugh th crrctr. Ths cn b crrctd by ddng qudrupl (bttm) tht frms ln crss vr thn dwn brrtn fr t th qudrupl-ctupl bfr t furthr trvl t th fcus pnt [4].


pplctns f Mcrscpy n Chrctrztn f Nn Mtrls

Nntchnlgy rvlvs n buldng nw mtrls n tmc lvl [7]. Strtng frm th rw mtrl, t vntully prcssd nd thn chrctrzd. Thrugh th chrctrztn prcss, th prprts f th nw mtrl s studd nd thn dvlpd fr pplctns. ur scty s mvng twrds ths nw r nd bttr tls r ndd t chrctrz th nw nn mtrl w r buldng. s mntnd n th ntrductn, mcrscpy n nntchnlgy chrctrztn s nvtbl.

s n xmpl, S/TM r TM cn prvd th sz, shp structur, nd rnttn f nn crystls nd nn wrs [3]. Wth th mgs btnd frm studs, mr nfrmtn ws btnd but th nn mtrl spclly rgrdng synthszng th sd mtrl. n stu studs usng th TM r dvlpng wth prbbl cnvrgnc f mcrscpy wth cmputtnl mtrl studs [8].

Mcrscpy s utlzd fr plymr nncmpsts fr rspc chrctrztn s wll. t th mlculr lvl, th us f SM, TM, HRTM nd FM, prvds th physcl nd chmcl prprts f nntubs tht wuld b bnfcl fr wll usd plymtrc mtrl [9]. Ths mthd ws dfnd t b mcrmchncl mdlng tht wuld prdct th bhvr f th cmpst rnfrcd wth fbrs lrgr thn th nnmtrl. n study by Njugun t.l. [9 ], thy dscussd th rl f mcrscpy tchnqus fr chrctrztn f plymr nncmpsts. Summry fllws [9]:






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