Far Ultraviolet Detector Standards

1 Page 1 NBSMeasurementServices: FarUltraviolet Detector Standards U.S.DepartmentofCommerce NationalBureauofStandards Open at page → 2 Page 2 CenterforRadiationResearch TheCenterforRadiationResearchisamajorcomponentoftheNationalMeasurementLaboratoryintheNational SureauofStandards. TheCenterprovidestheNationwithstandardsandmeasurementservicesforionizing radiati... Open at page → 3 Page 3 NBSMEASUREMENTSERVICES FARULTRAVIOLETDETECTOR STANDARDS L.RandallCanfield NilsSwanson CenterforRadiationResearch NationalMeasurementLaboratory NationalBureauofStandards Gaithersburg,MD20899 U.S.DEPARTMENTOFCOMMERCE,Malco... Open at page → 4 Page 4 LibraryofCongressCatalogCardNumber:87-619832 NationalBureauofStandardsSpecialPublication250-2 Natl.Bur.Stand.(U.S.),Spec.Publ.250-2,86pages(June1987) CODEN:XNBSAV Commercialproducts—materialsandinstruments—areidentified... Open at page → 5 Page 5 PREFACE Thecalibration andrelatedmeasurement servicesoftheNationalBureau ofStandardsareintendedtoassistthemakersandusersofprecision measuringinstruments inachievingthehighestpossiblelevelsof accuracy,quality,andproductiv... Open at page → 6 Page 6 FarUltravioletDetectorStandards ABSTRACT:Adescription isgivenoftheNBSprograminwhich specialphotodiodes forthefarultravioletspectralregion (5-254nm)aremadeavailableastransferstandards.These detectorsarecalibratedintermsof... Open at page → 7 Page 7 TABLEOFCONTENTS I Introduction 1 II DescriptionofService 2 a.Background b.Goals c.PresentServices d.FutureDirections IIIDescriptionofDetectorTypes 4 a.WindowlessPhotodiodeTransferStandard(5-122nm) b.WindowedPhotodiodeTra... Open at page → 8 Page 8 LISTOFFIGURES Page Figure1. Photocathodeanodizingarrangement 5 Figure2. NBSwindowlessfarultravioletphotodiode 7 Figure2a. NBSwindowlessphotodiodecathodesupport 8 Figure2b. NBSwindowlessphotodiodeanodestructure 9 Figure2c... Open at page → 9 Page 9 I INTRODUCTION Calibratedtransferstandarddetectorsforthefarultravioletareavailable fromNBStocoverthespectralregion5-254nm.Thesestandardsserveto enableoneworkingwithrelativelymonochromatic radiationinthisregionto determin... Open at page → 10 Page 10 II DESCRIPTIONOFSERVICE a.Background Duringtheperiod1955-1965thereoccurredarapidincreaseininterestin scientificactivityinthefarultraviolet,primarilyduetotwodevelopments. First,advancesinbothvacuumandopticaltechnologyhadl... Open at page → 11 Page 11 d.FutureDirections Itishopedthateventuallyallfarultravioletdetectorcalibration activitiescanbeconductedattheNBSSynchrotronUltravioletRadiation Facility(SURF-II),usingitscalculablefluxastheradiometricbase.This wouldelimin... Open at page → 12 Page 12 Ill DESCRIPTIONOFDETECTORTYPES a.TheNBSWindowlessPhotodiode (5-122nin) TheNBSWindowlessPhotodiodetransferstandarddetectoristheresultof temporalstabilityandspatialuniformitystudieswhichwereconductedatNBS inthe1960sonsever... Open at page → 13 Page 13 5 Open at page → 14 Page 14 2.PhotodiodeAssembly Figure2showstheconfiguration ofthisphotodiode.Acylindricalanodeis suspendedverynearthecathode,withamachinedTefloncomponentproviding supportforboth.Thephotocathode iselectricallyconnectedtoamachined p... Open at page → 15 Page 15 INCIDENT BEAM NBSPHOTODIODE(WINDOWLESS) (5-l22nm) Figure2 Open at page → 16 Page 16 NOTES: I .MAT :AL606 1 2.SCALE2-1 8 FIGUREZo Open at page → 17 Page 17 NOTES: 1 .MAT:SSTUBING.010WALL 2.SCALE4-1 9 FIGURE Open at page → 18 Page 18 J " " " NOTES: I .MAT:TEFLON 2.SCALE2-1 10 FIGURE2c Open at page → 19 Page 19 1,11 II ' 1 1 1 1 III 1 1 1 1 1 ' 11 NOTES I .MAT :TEFLON Z.SCALE2-1 FIGURE2d n Open at page → 20 Page 20 CM i I IL O o in-p E c c 0) 0) > (0 in in CM » I I r I I I I I|_j [ I I in o o o 12 Open at page → 21 Page 21 chargedparticlesduringoperation,sinceanysuchparticlesarrivingatthe photocathodewouldresultinanincorrectassessmentoftheradiantflux.The electricalcharacteristics andoperationalconsiderations onthefollowing pagearesuppliedw... Open at page → 22 Page 22 OPERATINGINSTRUCTIONS FORNB5MINDQWLES5 FftRUVTRANSFERSTANDARDPHOTODIODES Thephotodiodehastwooperatingelements:theanode,whichisthestainlesssteel cylinderprojectingfromtheTeflonbody,andthecathode,whichisthemirror-like surf... Open at page → 23 Page 23 b.WindowedPhotodiode(116-254nm) DuringthehistoryoftheNBSfarultraviolettransferstandarddetector programseveralsuppliersofwindoweddetectorshavebeenused.Initially satisfactoryphotodiodeswereobtainedfromtheStanfordElectronic... Open at page → 24 Page 24 Instructions forusingEVSDPhotodiodes TheEVSDmodel54-0-000photodiodeincorporates thefollowingmaterials: Window:Magnesiumfluoride Photocathode :Cesiumtelluride(oninsideofwindow) WindowSeal:Indiumalloy (meltsat"^700 TubeBod... Open at page → 25 Page 25 17 Open at page → 26 Page 26 c.RareGasIonizationChamber Theabsolutedetectorwhichformsthebasisforallpresentfarultraviolet detectorcalibrations atNBSistheraregasionizationchamber.Thebasic operationalprinciplesanddemonstration oftheabsolutenatureofthis... Open at page → 27 Page 27 in <D 3 iL 19 Open at page → 28 Page 28 IVCALIBRATIONTECHNIQUES Althoughtheexactcalibrationproceduresdifferinvariousportionsofthe spectralregioncovered,inallcasestheabsolutereferencestandardisthe raregasionizationchamber(2,3).Atwavelengths atwhichthephotonener... Open at page → 29 Page 29 where Iq=theemissivephotocurrent fromthephotodiode e =theelectroniccharge I =theradiantfluxincidentonthephotocathode e =thequantumefficiency(electrons/photon) ofthephotodiode maybeusedtodeterminethequantumefficiency. Com... Open at page → 30 Page 30 2.IonizationChamber(shortwavelengths) Theuseoftheraregasionizationchamberinthisregioniscomplicatedby thefactthatphotonenergiesarehighenoughtocreatebothmultiple ionization(morethanoneion-electronpairperevent)andsecondary... Open at page → 31 Page 31 where ^=totalioncurrent 6=electroniccharge P pressure T=temperature (C) y=gasabsorptioncoefficient (percm) k = 273.16 P g (T+273.16) * 760 Todeterminethefractionoffirstorder"f"atagivenwavelength, theabove valuesof"C"areu... Open at page → 32 Page 32 where f=fractionoftotalfluxwhichisfirstorder Ql =absorptiontermforIstorder Q2= " " for2ndorder e=electroniccharge i=measuredioncurrent Kit^2~multipleionizationcorrections for1st&2ndorders Therelationships forthegeneralca... Open at page → 33 Page 33 fluxpassingthroughtheionizationchamberfoil(asafunctionof wavelength). (Itis,ofcourse,impossibletooperateaphotodiode inthe presenceofionizationchambergas.)Thecalibration ofthemonitorphotodiode mustbetransferred toaworking... Open at page → 34 Page 34 V CALIBRATIONSYSTEMS a.SURF-IIDetectorCalibrationSystem(5-50nm) HISTORY Thecapabilityofcalibratingtransferstandardphotodiodes atwavelengths requiringgrazingincidenceopticswasestablished atNBSinthemid-seventies makinguseo... Open at page → 35 Page 35 27 Open at page → 36 Page 36 FoilChamber Abellowscouplesthemonochromator assemblytothebalanceofthesystem, witha4mmdiametercapillarylimitinggasflowtowardthemonochromator. Radiationemergingfromthecapillarymaybeinterceptedbyawindowless monitorphotodiod... Open at page → 37 Page 37 VACUUMSYSTEMS ThevacuumcomponentsassociatedwiththeSURF-IIdetectorcalibrationsystem areshownschematically inFig.7.Pumpinginthemonchromator sectionofthe apparatus isaccomplishedbytwo1101/sectriodeionpumps,withanopen cyclel... Open at page → 38 Page 38 IT OD in(T L 30 Open at page → 39 Page 39 Possibility (1)wascheckedfortwotypicalgoldblacksusedonaReeder thermopile.Thereflectivescatteringatthreewavelengths inthevacuumUV wascomparedtothatinthevisibleandnearinfraredandfoundtobethesame within1%oftheincidentintens... Open at page → 40 Page 40 32 Open at page → 41 Page 41 theionchambercurrentmeasurements aremade.Afterthemeasurements thegas ispumpedaway.)Thethermopile isthenrotatedbackontoitskinematicmounts behindthemaskforanothermeasurement.Alternatingmeasurements aremadein thiswayuntilen... Open at page → 42 Page 42 cr 1 oLU o -Jo crQ_LU LUZD1- XOLU h-oQ cr o « (D cr r o (D Z o < E cr LU Ll- CO —1 CL CL o ro< o>- cr 1-o LU FAGE QUEN VERT -JLU ocrO >o 34 Open at page → 45 Page 45 arrangementprotectsthesystemfromunforeseenpressureburstsorleaks.A separateroughingvalveallowsthemonochromator tobepumpeddownfrom atmosphericpressurewithoutturningoffthediffusionpump. (3)Thedetectorchambercontainsthetherm... Open at page → 47 Page 47 Thethermopile isrotateddown,clearoftheionchamberplates,andthe chopperstopped.Argonisadmittedtotheionchamberfor58.4and73.6nm measurements, andxenonforthe92.0nmmeasurement. Thegaspressureis adjustedtogiveacurrentratiobetwe... Open at page → 48 Page 48 TheMgF2~windowed diodesarecalibratedagainstthethermopile at23 wavelengthsfrom116.4to253.7nm.Thelightsourcegasishydrogenoverthe entirewavelengthrange.From116.4to160.8nm,thehydrogenlinespectrumis used.Above160.8nmthemolecu... Open at page → 49 Page 49 Monochromator Aonemeternormal-incidenceMcPhersonmodel225monochromator isusedwith itsownvacuumpumpingsystem.A15cfmmechanicalforepumpisusedforboth roughpumpingandforbackinga7"diffusionpump,whichusesDC705silicone pumpingflu... Open at page → 50 Page 50 a a 3 0) k. $ o Q. c o (0 E (0 « a o 3 Q csi T- 0) Ul o a. < 42 Open at page → 51 Page 51 toavacuumfeedthrough. Theanodesaretiedtogetherandatalltimes connectedtoanotherfeedthrough.Provisionismadeforrotationalrelocation ofeitherphotodiodeaboutitscenter,andquartzorVycorfiltersmaybe manuallyinsertedinthebeamtoai... Open at page → 52 Page 52 3S.73B.Q3B.B3B.-^33. E 33.2133.433. E 11212 3B.GSB.B3G.33B.B3B.B33.73B.333.433. B 33.3 B.^3B.B3S.03B.I213B.B3B.B3B.333.333.333.7 B.E3Q.B37.33B.IZ13B.Z33. B 33.B33.733. B 33.3 B.B3Q.B3S.33B.53B.333. B 33.^33.733.733.B 9B.... Open at page → 53 Page 53 VITREATMENTOFERRORS Uncertainties associatedwiththemeasurement ofquantumefficiencies are reportedineachReportofTestas"probableerrors",meaningthatthereisa probabilityof0.5thatthetruequantumefficiencyvaluesliewithinthe sta... Open at page → 54 Page 54 Intheabovesourcesofpossibleerror,thoseassociatedwithcurrent measurements aredueprimarilytotheprobableerrorofthecurrentsource usedtocalibratethemeasuringpicoammeters .Thegasabsorptionuncertainty involvestherepeatability o... Open at page → 55 Page 55 Intheaboveanalysis,thecrosssectionandmultipleyielddataaretaken frompublishedsourceswithinterpolationbetweenpublishedwavelengthswhere necessary. Since,inthisregion,thereductionofionizationchamberdata entailstheuseofgascon... Open at page → 56 Page 56 VIII CUSTOMERINTERACTION InteractionwithpotentialusersofNBSfaruvdetectorservicesgenerally leadstothesupplying(byNBS)ofcalibratedtransferstandardphotodiodes or inthesubsequentrecalibration ofthem.Inresponsetoinquiriesrega... Open at page → 57 Page 57 IXACKNOWLEDGEMENT TheassistanceofDrs.RobertP.Madden,EdwardB.Saloman,DavidL.Ederer,and Mr.LannyHugheyisgratefullyacknowledged. Dr.MaddenhasbeenGroupLeaderof theFarUltravioletPhysicsSectionthroughouttheperiodduringwhichthe... Open at page → 58 Page 58 REFERENCES 1.L.R.Canfield,R.G.Johnston&R.P,Madden,"PreliminaryReporton Photoelectric DetectorTransferStandardsfortheVacuumUltraviolet", NBSReport#9897. 2.J.A.R.Samson,"AbsoluteIntensityMeasurements intheVacuumUltraviolet... Open at page → 59 Page 59 6.R.P.Madden,"Availability ofNBSRadiometricStandardsforSolarIrrad- ianceStudies",Proc.WorkshoponSolarUVIrradianceMonitors, 79(1980). 7.E.B.Saloman,"TypicalPhotoefficiencyBetween20-250eVofWindowless XUVPhotodiodeswithTung... Open at page → 60 Page 60 IONCHAMBERS 1.J.A.R.Samson,"AbsoluteIntensityMeasurements intheVacuumUltraviolet", J.Opt.Soc.Am.54,6(1964). 2.J.A.R.Samson&G.N.Haddad,"AbsolutePhoton-fluxMeasurements inthe VacuumUltraviolet", J.Opt.Soc.Am.64,47(1974). 5... Open at page → 61 Page 61 AppendixA FORMNBS—259 |REV.12-781 U.S.DepartmentofCommerce NATIONALBUREAUOFSTANDARDS WASHINGTON,DC.20234 533.04 REPORTOFTEST September 9,19B5 for ABCCorporation Sampi e : Farultravioletphotodiode, EVSDmodel54-0-000,seria... Open at page → 62 Page 62 Results :(EVSDModelNo.54-0-000photodiode, serialno.XXX-X, calibrated9/85.) Wavelength (A) QuantumEfficiency (xlQO) ProbableError(%) 1164 4.02 6 1180 4.06 6 1216 6.61 6 1254 8.86 6 1354 9.17 6 1403 8.00 6 1441 7.62 6 1487... Open at page → 63 Page 63 Measurements associatedwiththiscalibrationweremadeby: L.Randal 1Canfield (301)921-2031 Reportofthiscalibrationapprovedby: RobertP.Madden GroupLeader,533.04 FortheDirector Wi 1hamK.Utt Chief,RadiationPhysicsDivision Order... Open at page → 64 Page 64 FORMNBS—259 (REV.12-781 U.S.DepartmentofCommerce NATIONALBUREAUOFSTANDARDS WASHINGTON,DC.20234 533.04 July1,1986 REPORTOFTEST for ABCCorporation Samp]es : Farultraviolet photodiode,windowless, AI2O2photocathode , NBSseri... Open at page → 65 Page 65 Resu1ts:(NBSwindowlessFarUVPhotodiode,serialno.123,calibrated April,1986). Wavelength (A) QuantumEfficiency (xlOO) ProbableError(%) 50 3.66 15 55 4.99 10 60 6.25 10 65 7.19 10 70 8.07 10 75 8.80 10 80 9.43 10 85 9.85 10... Open at page → 66 Page 66 Wavelength (A) QuantumEfficiency(xlOO) ProbableError(%) 622 639 657 669 683 699 712 735 752 771 800 818 844 865 886 920 1026 1216 16.88 17.60 17.83 17.94 17.81 17.42 17.39 16.43 15.57 14.68 13.35 12.41 11.54 10.91 10.32... Open at page → 67 Page 67 Measurements associatedwiththiscalibrationweremadeby Reportofthiscalibrationapprovedby RobertP.Madden GroupLeader,533.04 FortheDirector WilliamR.Ott Chief,RadiationPhysicsDivision OrderNo.:ABC123 TestNo.: 123/86-1 Date:... Open at page → 69 Page 69 AppendixB DETAILEDOPERATIONOFSURF-IIDIODECALIBRATIONSYSTEM CalibrationSequence Inordertobeabletocalibrateoutgoingphotodiodes, acalibratedworking standardmustexist.Theprocedureenablingonetoachievethisinvolvesthe useofther... Open at page → 70 Page 70 VOLTAGES&PRESSURES Thefollowinghavebeenestablished as"normal"operatinglevelsforbias voltagesandionchamberpressures: Unit Wavelengths (nm) Bias(v) monitor 15-60 60 5-15 100 wkgstd 15-60 60 5-15 100 samples 15-60 60 5-15 1... Open at page → 71 Page 71 INITIALIZING WavelengthDrive Note:beforerunningthisroutine,gratingtobeusedmusthavebeenselected andmaskssettogiveproperillumination. Menuitem#29.Afterselectionofitem,atexperimentturnonwavelengthdrive powersupply,presscomm... Open at page → 72 Page 72 FILTERS Filtersareusedattwoplacesinthesystem:justahead(towardmono)ofthe monitordiodeandattheentrancetotheionchamberarea.Themonitorfilters (Alandpolypropylene) arepneumatically insertedbytheprogram,butthe selectionofthepr... Open at page → 73 Page 73 OPENINGBEAMLINE BeforeconsideringopeningtheBL-9|atevalve(controlsoninterlockpanel) themonochromator mustbeonthe10 rangeandmusthavepassedRGAsince lastbeingopenfortest.Aspotcheckofthehydrocarbonpeaksmaybemadeat anytimeviat... Open at page → 75 Page 75 AppendixC THERMOPILECALIBRATIONPROCEDURE I.Turnonlightsource 1.Outgasfilament15A.(flapvalveclosed) 2.OpenKrvalveslowly,press.about2-3x10 ^ Torr 3.Turnupminorarctoover0.2A. 4.Startmajorarc.RaiseVariacquicklytogetcurrentst... Open at page → 76 Page 76 Ifnecessary,adjustslitwidthbyreadingresidualionchambercurrenton electrometer, settingrighthandscannerto#1. III.DataAcquisition 1.Bothflapswideopen(entranceandexitslits),nottripped. 2.TCtripsettingsraisedonbothpumps 3.Gat... Open at page → 77 Page 77 #1onpapertape #4Shutsgasvalve,pumpsoutionchamber.Waits40seconds,repeatsTP background . #5Flapvalveopens-TPsignal #3Ionchamber #2onTape #4Pumpsoutchamber,TPbackground #5TPsignal #3Ionchamber #3onTape #4Pumpsoutchamber,TPb... Open at page → 78 Page 78 II.TurnOnLightSource(exactproceduremayvary) 1.Outgasfilament15A. 2.LetinKr2-3x 10"^ Torr. 3.Turnupminorarctoabove0.2A. 4.Startmajorarc.Raisevariacquicklytogetcurrentstarted. Mayneedmaximumminorarccurrentorhigherfilamentc... Open at page → 79 Page 79 2.Startwith"Ju00,Resume". Enterdate(2digitsfordayofmonth) Computerreturnsdiodeno.,wavelengthandphotoelectric correction. EnterFvalue.Resume. EnterfullscaleKeithleyrange.Resume.Mustbenotgreaterthan 3X 10"^ A. Computerprin... Open at page → 80 Page 80 Afterlastw.l.(2537A),updatepermanentdatacard: 1)"JuIS(x-yaxes),Resume"printsoutforeachw.l.the %differencebetweenpreviousaverageQ.Eff.andthepresent Q.Eff.,thenewaverageQ.Eff.,andthenewstandarddeviation. 2)Thenrcl[][]32,sw... Open at page → 81 Page 81 AppendixD DIODECALIBRATIONPROCEDURE Initializingsystem Sequence : 1.Perforinlightsourcestartup(vacuum) 2.Turnonallelectronics (leftscanneronch,3) 3.Ventexperimentalchamber 4.Loadsamples(blowoffdust) (ifsamplediodefromcus... Open at page → 82 Page 82 PROGRAMSFORDIODEINTERCOMPARISON ANALYSIS 5-JUN-84 Plottingrunningratiosvstime Cards:075 049 Refratiodatacard(#lowerleftofplot) Datacardforlastpointpreviouslyplotted Datacard(s)forsubsequentdata Prep:1.calculator &plotter... Open at page → 83 Page 83 Running: (ifnewratiosare1/x,flag) 1.juO0(res)-auto toend (ifeitherdatacarddisagreeswiththeother,error -ifso,clear,re-storebothdatacards 2.atend,re-recordintercomparison card: rcl32(writepos)entercard(returntoreadpos) PHO... Open at page → 84 Page 84 point(thestartingposition)aftereachline tocheckforlightsourcedriftandmakeany necessarycorrections. Themagnitudeofthechange relativetotheoriginalvalueisprintedoutafter anidentifiergivingthelinenumber. Themagnitude ofthech... Open at page → 85 Page 85 Notethatthevaluesshownforentriesarecorrect fortheevsdphotodioderoutinelyscanned...other detectorswill,ingeneral,requiredifferentvalues. CALIBRATION OFWINDOWLESSNBSPHOTODIODES BYA-BINTERCOMPARISON (490A-1216A) Function: T... Open at page → 86 Page 86 Startingprogram: 1.JuOO(Res),enter:date sample# standard#(loopsto00ifwrongcard) Runningprogram: Aftersuccessfulcompletionof584Adata,programwillhalt forachangeofsourcegas . 1.SwitchsourcegastoKr,setmajorarcto2amperes. 2.W... Open at page → 87 Page 87 IONCHAMBER/DIODECALIBRATION Functions : Thecalibrationofawindowless (NBS)photodiode inthewavelength range496-920Abytheuseofararegasdoubleionizationchamber todeterminetheabsolutefluxfromthemonochromator .Thetwo detectorsa... Open at page → 88 Page 88 2ampmajorarccurrent,opentheHeshutoffvalve atthemanifold. Thesourcewillverylikelygoout. afterthepressurehasrecoveredtothepreviousKr level,trytheprocedureagain. Itwilltakeseveral triesbeforethemajorarcwillstayonwithHe. Whe... Open at page → 89 Page 89 6. Readjustslitsto150microns,enter newmonochromator presureandhitresume. Afterseveralmorewavelengths, theprogramwillstop foraswitchtoNeinthesource. Neisregulatedwitha needl^valveonly—afteritisfirstopenedandset(about 1x10... Open at page → 90 Page 90 NBS-n4A(REV.2-8C) U.S.DEPT.OFCOMM. BIBLIOGRAPHICDATA SHEET(Seeinstructions) 1.PUBLICATIONOR REPORTNO. fsIBS/SP-250/2 2.PerformingOrgan.ReportNo 3.PublicationDate June1987 4.TITLEANDSUBTITLE j^^^^^^^^j^^j^^SERVICES: FarUl... Open at page → 91 Page 91 PUBLICATIONS INTHESP250SERIESFROMTHECENTERFORRADIATIONRESEARCH SP250-1 NBSMeasurement Services: SP250-12 SpectralRadianceCalibrations J.H.Walker,R.D.Saunders, andA.T.Hattenburg SP250-2 NBSMeasurement Services: SP250-13 F... Open at page → 92 Page 92 U.S.DepartmentofCommerce NationalBureauofStandards Gaithersburg,MD20899 OfficialBusiness PenaltyforPrivateUse$300 Open at page →