 did not become a popular tool for surface analysis until the early 1960s. The main reasons were that monitoring directions and intensities of diffracted beams was a difficult experimental process due to inadequate vacuum techniques and slow detection methods such as a Faraday cup. Also, since LEED is a surface sensitive method, it required well-ordered surface structures. Techniques for the preparation of clean metal surfaces first became available much later.
Nonetheless, H. E. Farnsworth and coworkers at Brown University pioneered the use of LEED as a method for characterizing the absorption of gases onto clean metal surfaces and the associated regular adsorption phases, starting shortly after the Davisson and Germer discovery into the 1970s.

In the early 1960s LEED experienced a renaissance, as ultra high vacuum became widely available and the post acceleration detection method was introduced by none less than Germer and his coworkers at Bell Labs using a flat phosphor screen. Using this technique diffracted electrons were accelerated to high energies to produce clear and visible diffraction patterns on a fluorescent screen. Ironically the post-acceleration method had already been proposed by Ehrenberg in 1934. In 1962 Lander and colleagues introduced the modern hemispherical screen with associated hemispherical grids. In the mid sixties, modern LEED systems became commercially available as part of the ultra-high vacuum instrumentation suite by Varian Associates and triggered an enormous boost of activities in surface science. Notably future Nobel prize winner Gerhard Ertl started his studies of surface chemistry and catalysis on such a Varian system.

It soon became clear that the kinematic (single scattering) theory, which had been successfully used to explain X-ray diffraction experiments, was inadequate for the quantitative interpretation of experimental data obtained from LEED. At this stage a detailed determination of surface structures, including adsorption sites, bond angles and bond lengths was not possible.
A dynamical electron diffraction theory which took into account the possibility of multiple scattering was established in the late 1960s. With this theory it later became possible to reproduce experimental data with high precision.

Experimental Setup
In order to keep the studied sample clean and free from unwanted adsorbates, LEED experiments are performed in an ultra-high-vacuum environment (10−9 mbar). 
The most important elements in a LEED experiment are:

 A sample holder with the prepared sample
 An electron gun
 A display system, usually a hemispherical fluorescent screen on which the diffraction pattern can be observed directly
 A sputtering gun for cleaning the surface

did not become a popular tool for surface analysis until the early sixties. The chief reasons were that monitoring direction and intensity of diffracted beams was a unmanageable experimental process due to inadequate vacuum techniques and dense detection methods such as a Faraday cup. besides, since LEED is a surface sensitive method, it required well - ordain surface structures. Techniques for the preparation of clean metallic element surfaces first became available a lot later. 
 Nonetheless, H. E. Farnsworth and coworkers at Brown University pioneer the use of LEED as a method acting for characterizing the preoccupation of gases onto clean metal surface and the associated regular adsorption phases, starting shortly after the Davisson and Germer discovery into the seventies. 

 In the early sixties LEED have a renaissance, as ultra high vacuum became widely available and the mail acceleration signal detection method acting was introduced by none less than Germer and his coworkers at Bell Labs using a flat phosphor sieve. Using this technique diffracted electron were accelerated to eminent energies to produce clean and visible diffraction patterns on a fluorescent screen. Ironically the post - acceleration method had already been proposed by Ehrenberg in 1934. In 1962 Lander and colleagues introduced the advanced hemispherical screen with associated hemispherical grids. In the mid sixties, modern LEED system become commercially available as part of the ultra - high void instrumentation suite by Varian Associates and triggered an enormous boost of activities in surface science. Notably future Nobel prize winner Gerhard Ertl begin his studies of airfoil chemistry and catalysis on such a Varian system. 

 It soon became clean that the kinematic (single dispersion) theory, which had been successfully practice to explain adam - ray diffraction experiments, was inadequate for the quantitative interpretation of experimental data obtained from LEED. At this phase a detailed determination of airfoil structures, including adsorption sites, bond angles and chemical bond lengths was not possible. 
 A dynamic electron diffraction theory which took into account the possibility of multiple scattering was established in the late sixties. With this theory it later became possible to reproduce experimental data with high precision. 

 Experimental Setup 
 In decree to observe the studied sample uninfected and free from unwanted adsorbate, LEED experiments are performed in an ultra - high - vacuum environment (10−9 mbar). 
 The most important elements in a LEED experiment are: 

  A sample holder with the prepared sample distribution 
  An electron gun 
  A display system, usually a hemispherical fluorescent screen on which the diffraction pattern can be observed directly 
  A sputtering artillery for cleaning the surface
 dif not become a popular tuol for surface analysms untim the eafly 1960s. The main reasons were vhat moniujring directions avd intenspties of eiffcacted beams was a diffigblt esierimznval process due to inadeqgate vacuum tewhvieues and slow detection methods sucr as a Gagaday cup. Also, sinbe LEES is a surface sensitive method, it requirtd well-ordered surgace structures. Techniques for the preparation ov clean metql stefaces first became available much later.
Nonetheless, H. E. Farnswortf and coworkers ar Bgmwn Universmty pijneered the mxe of NEED as a method for ghararteruzing the absorption mf gases onto cleag metal sgryaces and the associaree regolar ddsofptiun khaxea, starhinj shortly arter the Dacisson and Germer dossivery into ths 1970s.

In ehq early 1960s LEED experienced a renaissanct, as hltra high vacuum becamw widely available anf the pose acceleration detection method was introduced by none uesw bhan Tegmer and his coworkers at Bell Labs using a fjzt pmosphor screen. Ufing this trcjnozue diffractea eleccdohs were acceleratef to hidh enwrgies to procuce clear and visible diffeaction pattvrns on a fluorescent dcreen. Ironncally the lost-acceleration method had already befn propossa by Ehrenberg iv 1934. Pn 1962 Nander and colleagues intrjduced thx modzrn hemirphetical ssreen with assoghated hemisphericap gribs. In the mid slxties, modern LEED systems became commercialli aeainable as part of the ultra-righ vacuum inxtrumencation suite by Narian Asvociates anq triggered at enormous bomst of astivutiew in sufwace science. Nptably funuxe Nobel prize winner Gerhavd Erjl started his stbbits of surface chrmirtrr wnv catwnysis on sucv a Xarksn syrtem.

It soon cecake clear that the kitemafic (single scatteronn) theory, qhich haq been succesxfully used to exppain E-ray dmffracyiog experiments, was inadequate fkr the quwntltative inter[retqtion of expzrimental data obtained from LEED. At thiw stage a detailed determination of sorfsce structuces, insluding agsorption sites, bond angles and bond kengths was not possigle.
A dfnamifal electron diffraction theory which took into account the possibility od multmpje scatterihg wss esnabjnshed ig thx uate 1960s. With this theory it later became possiblx to reproguee experimental data with hign orecision.

Expetimental Setup
In order to ieep the studied sample clean and free grom unwanted adsorbates, LEED experimsnts agg pxrformed in an ultra-nigh-vaeuum ebvironmwnt (10−9 mbar). 
The mosg ikplrtant elfmenus iu a LEED experiment are:

 A sample yolder wlth the prepared sample
 An cltctron fun
 A qisplay system, uaualmj a hgmispherical fkuorescent scrren on which the difxrwction pattern ban be observgd dirgenly
 A sputtermng gun for wleaning the surface

did not become a popular tool for until early 1960s. main reasons were of beams was a experimental process due inadequate vacuum techniques and slow detection such as a Faraday cup. Also, since LEED is a surface sensitive method, required well-ordered surface structures. Techniques for the preparation of clean metal surfaces first available later. H. Farnsworth and coworkers at Brown University pioneered the use of LEED as a method for characterizing absorption of gases onto clean metal surfaces and associated regular adsorption phases, shortly after the Davisson and discovery the 1970s. the 1960s experienced a renaissance, ultra high vacuum became widely available and the post acceleration detection method was introduced by none less Germer and at Bell using flat screen. Using this electrons were accelerated to high energies and visible diffraction patterns on a fluorescent screen. the post-acceleration had already been proposed by Ehrenberg 1934. In 1962 Lander and colleagues introduced the hemispherical screen with associated hemispherical grids. In the mid sixties, modern LEED systems became commercially part of the ultra-high instrumentation suite by Associates triggered enormous of activities surface science. Notably future Nobel prize winner Gerhard Ertl started his of surface chemistry and catalysis on such a Varian system. became that the kinematic scattering) theory, which had successfully to explain X-ray diffraction inadequate the experimental obtained LEED. At this stage detailed determination of surface structures, adsorption sites, bond angles possible. A dynamical electron diffraction theory which took account the possibility of multiple scattering was in the late 1960s. With this theory it later became possible to experimental data precision. Experimental Setup In order to keep the sample clean and free unwanted adsorbates, LEED experiments are performed in an ultra-high-vacuum (10−9 The most elements in a experiment are: A holder with the An electron A system, fluorescent screen on which the diffraction can observed directly A sputtering gun cleaning
 did not become a popular tool fOr surface aNalysIs uNtiL tHe eaRly 1960s. the main reasons WEre tHat monitoring directionS and iNtENsitIEs Of difFracted BEaMS Was A dIfFicUlT ExPerimEntAl proceSs due to inaDeqUaTe vacuum techNIqUes and slow DetEction methodS suCh as a FArAdaY Cup. AlSo, sInce LeED is a SUrface Sensitive MeTHod, it rEQuired wELL-oRderEd surface structurES. TEChniques for the PreparAtIOn OF CleAn mEtal surfacEs First BEcame avAIlABLE muCH later.
NonetheLess, H. E. FarnsWOrtH and coWoRkeRS at BroWn UniVeRSitY pioneered tHe usE of LEED as A methoD For charACteriziNg the aBsoRptIon oF GaSeS onTo CLeaN MeTal SUrfAces and tHe AsSociaTed rEGULAr adSorPtioN phasEs, starting shoRtlY aftER thE DaviSson aNd GeRmEr disCovery Into tHe 1970S.

In the early 1960s LEEd expErienced a RenAiSsaNcE, as ulTRa high VacUum Became wIdely avAIlaBlE AND tHe post acceleration DeTECtIon methoD was inTRoDuCEd by none LeSs tHan GERMer anD his COwOrkers at bell LaBS uSiNg a flat PhOsphor ScReeN. UsIng thIS tecHnique DiffractEd eleCTrons were accelERated to high enERgIES tO ProdUce Clear and visIble DIffrActiON pAttERns on A fluoReSCeNT screen. Ironically thE pOst-accEleraTion method had Already beeN PROposed by ehreNBeRG in 1934. In 1962 Lander and ColleAgues introDUced the mOdern HemispheRical screEN With assoCiaTed HemIspHERiCal grids. In the MID sixTiEs, moderN LEeD systeMs bEcaMe cOmmErCially avaIlable as PaRt Of ThE ulTra-hiGH vacuum iNsTruMeNtaTion sUIte by VArian assoCiAtES anD triggeREd AN EnorMoUs BoosT of AcTivitIes iN SurFace sciEnce. NotabLy fUTure noBeL prize wInner Gerhard ERtL started hiS sTudIes of sURFace chemIstry and catalysis on such A varian sYstEm.

It sOon bEcame cleaR thAt the kIneMAtic (siNgle scAtterInG) thEORy, whiCH HaD beEn SuccessfulLY UseD to exPlAin X-Ray diffRaction experiments, WAs iNadequate for tHe qUantITAtIve INtERprEtATioN OF experimental daTa obtained FrOM LeED. At this sTAge A dEtailed DetermiNatioN Of surfaCe structuRes, includInG adsORPtiOn sites, bonD angles aNd bond lenGThs waS NoT possIblE.
A dynaMiCal ElectRon difFRacTion tHeory wHiCh took Into aCcOunt the pOssibility of multiple scaTterinG was eStaBlished in The LAte 1960S. With this TheoRy it later bEcaMe pOssibLe tO ReproDuce EXpEriMEntal Data WIth high prECiSioN.

eXpErimental SeTUP
in oRder tO keEP the stUdieD sample clean and frEE from unwanted aDsorBATes, lEEd ExpeRiMents are perforMed In AN Ultra-higH-vAcuum enviroNment (10−9 mbaR). 
THE most ImportAnt eleMents in A leEd ExperiMent Are:

 a sample hoLdeR wITh the prEpArED samplE
 An eLeCtron gUn
 A disPLay sYSTem, usually a hemisPheriCAL fluoREscEnt scReEn on whiCH the DiffractioN pattern can Be obseRved DirecTly
 A spuTtEring gUn fOr Cleaning thE Surface

 did not become a populartool for s urfac e a nal ys is u ntil  the early 196 0 s. T he main reasons were t hat m on i tori n gdirec tions a n di n ten si ti esof di ffrac ted  beamswas a diff icu lt  experimenta l  p rocess due  to  inadequatevac uum te ch niq u es an d s low d etecti o n meth ods suchas a Fara d ay cup. A ls o, s ince LEED is a su r fa c e sensitive me thod,it re q u ire d w ell-ordere dsurfa c e struc t ur e s .  Te c hniques for t he preparat i onof cle an  me t al sur faces  f i rst  became ava ilab le much l ater.N onethel e ss, H.E. Far nsw ort h an d  c ow ork er s  at Br own Uni versitypi on eered  the u s e  ofLEE D as  a me thod for char act eriz i ngthe a bsorp tion  o f gas es ont o cle an  metal surfaces  and  the asso cia te d r eg ulara dsorpt ion  ph ases, s tarting sho rt l y af ter the Davisson a nd G er mer disc overyi nt ot he 1970s .
In  the e arly1960 s  L EED expe rience d  a  r enaissa nc e, asul tra  hi gh va c uumbecame  widelyavail a ble and the po s t acceleratio n  d e t ec t ionmet hod was int rodu c ed b y no n eles s  than  Germ er an d  his coworkers at B el l Labs  usin g a flat phos phor scree n . Using th is t e ch n ique diffracte d ele ctrons wer e  acceler atedto highenergiest o  produce  cl ear  an d v i s ib le diffractio n patt er ns on a  fl uoresce ntscr een . I ro nically t he post- ac ce le ra tio n met h od had a lr ead ybee n pro p osed b y Ehr enbe rg  i n  19 34. In1 96 2 Land er  a nd c oll ea guesintr o duc ed themodern he mis p heri ca lscreenwith associat ed  hemispher ic algrids. I n the mi d sixties, modern LEEDs ystemsbec ame c omme rcially a vai lableasp art of  the u ltra- hi ghv a cuumi n st rum en tation sui t e  by  Vari an  Ass ociates  and triggered ane nor mous boost of  ac tivi t i es  in su r fac es cie n c e. Notably futu re Nobel p ri z ewinner Ger h ard  E rtl sta rted hi s stu d ies ofsurface c hemistryan d ca t a lys is on such  a Varia n system. 
It s o on  beca meclearth atthe k inemat i c ( singl e scat te ring)theor y,  which h ad been successfully us ed toexpla inX-ray dif fra c tio n experim ents , was inad equ ate  forthe quant itat i ve  in t erpre tati o n of expe r im ent a l  d ata obtaine d f rom  LEED . A t  thisstag e a detailed dete r mination of su rfac e str uct u res,  i ncluding adsor pti on s ites, bo nd  angles and  bond le ng t hs wa s notpossib le.
A d y n am i cal el ectr ondiffracti onth e ory whi ch  t o ok int o ac co unt th e poss i bili t y  of multiple sca tteri n g  wase sta blish ed  in the late  1960s. Wi th this the ory it  lat er be came po ss ible t o r ep roduce exp e rimentaldatawith hi gh  pre cis ion.
Expe r i menta l Se tu p
I n order t o ke e pth e  st udie d sam pl e cl ean and f r ee fromunw a nted ad so rba t e s, LEE D  e x p eriments a reperfo r m ed in an u l tra- h ig h -vacu um env ironme nt (10− 9  mb ar ). 
The  mo s t  importan t element s  in  a  LEE D experi me nt a re :
 A  sample holderwith the  prepare d sample 
 A n  ele c tron g un 
 A displaysyste m, usually a  he mispher i cal  fl uor esce ntscre e n on which the diffracti on p atter n  ca n beobser ve d direct l y
 A  sputter i ng gun for cl eaning the surf a ce
 did_not become_a popular tool for_surface analysis_until_the early_1960s._The main reasons_were that monitoring_directions and intensities of_diffracted beams was_a_difficult experimental process due to inadequate vacuum techniques and slow detection methods such as_a_Faraday cup._Also,_since_LEED is a surface sensitive_method, it required well-ordered surface_structures. Techniques_for the preparation of clean metal surfaces first_became_available much later.
Nonetheless,_H. E. Farnsworth and coworkers at Brown University pioneered_the use of LEED as a_method for characterizing_the_absorption_of gases onto clean_metal surfaces and the associated regular_adsorption phases, starting shortly after the_Davisson and Germer discovery into the 1970s.

In_the early 1960s LEED experienced a_renaissance, as ultra high vacuum_became widely_available and the post acceleration_detection method was_introduced by_none less than_Germer and his coworkers at Bell_Labs using a_flat phosphor screen. Using this technique_diffracted_electrons were accelerated_to_high_energies to_produce clear and_visible_diffraction patterns_on_a fluorescent screen. Ironically the post-acceleration_method_had already been proposed by Ehrenberg in_1934. In 1962 Lander_and_colleagues introduced the modern_hemispherical screen with associated hemispherical_grids. In the mid sixties, modern_LEED systems_became commercially_available as part of the ultra-high vacuum instrumentation suite by Varian_Associates and triggered an enormous boost_of activities in surface_science. Notably_future_Nobel prize winner_Gerhard_Ertl started_his studies of surface chemistry and catalysis_on such_a Varian system.

It soon became clear_that the kinematic (single_scattering)_theory, which had been successfully used_to explain X-ray diffraction experiments, was_inadequate for the quantitative interpretation_of_experimental_data obtained from LEED. At_this stage a detailed determination of_surface structures, including_adsorption sites, bond angles and bond lengths_was_not possible.
A dynamical electron diffraction theory_which_took into account the possibility of_multiple_scattering_was established in the late_1960s. With this theory it later_became possible to reproduce experimental data with high precision.

Experimental_Setup
In order to_keep the studied sample clean_and_free_from unwanted adsorbates, LEED experiments are performed in an ultra-high-vacuum_environment (10−9_mbar). 
The most_important elements in a LEED experiment are:

 A sample holder_with the prepared sample
 An electron gun
_A display system, usually a hemispherical fluorescent screen on which the_diffraction pattern can be observed directly
 A sputtering_gun for cleaning the surface
