发同步辐射与表面科学

内什么是同步辐同步辐射光源的基于同步辐射的同步辐射表面分析技术vs常规表面分析表面科学的重要同步辐射在表面同步辐射光电子什么是同步辐 同步辐射装置的基合肥同步辐射装置同步辐射光同步辐射光源与常规光源的比同步辐射是一种性能优异的第三代第—代 192019401960 1895年发现X射线以来光源亮度的提同步辐射经历三代的发已开始建造第代光源强度谱带准直性脉冲偏振同步辐射应同步辐射应化药§目标不同光源覆盖光谱范围和研究的科学HLS亮度曲Red:GPLSmodeBlue:Red:GPLSmodeBlue:16nm.radmodeSolid:dipoleradiation :undulatorradiationbrilliance/1

Photonenergy

HLS改造内低发射 大幅提高HLS供光质满能量注避免低能束流短和不稳定性度造成的注入过程现象。光源系统将工作基于同步辐射的各种技同步辐射用于研究表面科学的谱学和（HRUPS和近边X光电同步辐射荧光光谱表面X射线散射同步辐射在表面科

表面分析技术：同步辐射vs常动能：40－100eV低能（5-10eV)或高能（>5keV)SRPES－表面灵C.J.Weststrate,etal,J.Phys.Chem.C,2008,112,SRPES－不同深Rh3dandPd3d:hv=645,850,1486.6Pt4f:hv=350,630,1496.6MFPs:0.7,1.0,1.6

Tao,etal,Science,SRPES强度与光电离截IIAAD(EA)LA()J0(x,y)T(x,y,EA)NA(x,y,z)exp[z/(cosd(EA))]x LA(γ):A元素的角不对称因子nA(x,y,z):表面A元素的原子浓度θ:测量的光电子相对于表面法线的夹光电vs光子能Mg

Al

Mg

Al1AlMg1AlMg224MgAlMgAlMgMgAlMgAl1nmO

N

IntensityIntensity常规KiskinovaetalSurf.Sci.136(1984)285

526 BindingEnergyZhu,Kinne,etal,Surf.Sci.,529(2003)384.Alanine/ChiralH 2OGladys,etal.,JPCC,IntensitpCO=IntensitpCO=2.5x10-9T=95K,Time/spectrum:3Sec.On-OC BindingEnergyIntensity[At=0.5平衡态下平衡态下on-top=0.25bridge=0.25(Kinne,Fuhrmann,Whelan,Zhu,etal,J.Chem.Phys.117(2002)10852)固体的三维周期势在表面或界面不连续，从而表面与界面科学：从原子－分子水平上了解和认识在

A.

G. 奖从表面科学到50年变探测电子的检测器和真空系统等几个部分组成 电子能谱常用激X射线、、单色化的X射线将X射线用石英晶体的面沿Bragg反射方向衍射后双阳极X射线源可使双阳极X射线源电子能量分 真空条件下（低于10-5torr）半球形电子能量分半球半球形分析器示意

RE 检测检测器通常为单通道电子倍增器和多通道倍增子流10-13～10-9A10-4~通道电子倍增器是一种采用连续倍增电极）109。检测器（PSD）或多阵列检测器真空电子能谱仪的真空系统有两个基本功发射出来的电子的平均自由程相对于谱仪的尺11L=10-6torr·s，常温下吸附一层气体分子所需时10-6torr时为1秒；10-10torr时为10000样品电子能谱仪原则上可以分析固体、气体和液体样气气采用差分抽气的方法引进样品定液校正或液片再固定在样品托上

112真空加氩离子刻固固同步辐射光电子同步辐射光电子能谱根据所选光子能量的不同可以提供1）清洁表面或有化学吸附物的表面的电子结参与表有关电子4面功吸附分子鉴定除H和He之外的全部元素及其定性、定量元素的光电子能谱

同步辐射在表面科学中的应用研究半导体表面研究催化反应研究表面研究分子自半导体表面的电子 S1,S2:B:D:Second

Choetal.,Surf.Sci.半导体表面的电子+h+ Interface

eMetal-半导体表面的电子半导体表面的电子 InterfaceSemiconductor催化剂的结构及反应利用同步辐射 催化剂表面的化学组成、电子结构、元素价态、催化剂表面的热稳定性、催化反应前后表面结构发生的变化，以及反应分子在表面的吸附态、吸附类型（化学吸附还是物理吸附）、吸附位置等，探测表面吸附或反应的 和分子发生T.E.Madey,PNAS,2002,99,催化剂的结构及反应催化剂的结构及反应机理CeOx/u(1

（Water-gasshift,OxidizingaCe-Au(111)alloyinO2atKandsubsequentannealingto690Rodriguez,etal.,Science,

CeO2(111)CeO2-CeO2-STMimageacquiredafterdepositingCeinanatmosphereof1.5×10−7torrCeO2-CeO2-催化剂的结构及反应机理–Water-gasshift,Water-gasshift,20-30%coveredAu(111)hasThesystemswithahighcatalyticactivityalsohaveasignificantconcentrationofOvacanciesandassociatedCe3+cations.InterfaceparticipatesinRodriguez,etal.,Science,催化剂的结构及反应机理–COxhft,WGSCO+H2O→CO2+H2TogetherwithTheadsorptionanddissociationofwatertakeplaceontheoxide,whereasCOadsorbsonsitesofthegoldsubstra nearby(bifunctionalcatalyst).Allofthesubsequentstepsoccuratanoxide-metalinterface.Rodriguez,etal.,Science, O 2

原位表面 Omicron

原位表面 X-rayorX-rayor250l/s

Pana=3x10-11Pprep=5x10-11

5005001600BESSYII,Beamline:U49/1-SGM,PGM1(UndulatorResolutionsettomatchtimeresolutionneeded (180meVforC1s)Photonenergyforsurfacesensitivemeasurements (Ekin100eV)Shortmeasurementtimes (somesecondsperspectrum)PropertiesofaPropertiesofamolecular(welldefinedstartof→AdsorptionSpaciallyconfined“high”pressure(upto10-5(expandingthepressurerangefor→ReactionVariablekinetic(andinternal)energyofmolecules(“activatedadsorption”)→Identificationofadsorbates–CH4/Pt(111)andNOuptakeonNOuptakeon

530.6,fcc+hcpT=110

Non-

530.3,IntensityIntensity

BindingEnergyO1s:7s(11N1s:5s(10O1s:250NO1s:7s(11N1s:5s(10O1s:250N1s:240 Normal wasNormalizedtophotonh=650

532.0,on- NOuptakeonNOuptakeonT=250

BindingEnergy

CurveCurveIntensityvs110K250530.3eV,530.6eV,IntensityIntensity

O NOexposureFittingfunction:Doniach-SunjicfunctionsconvolutedwithGaussians.530.3eV:fccNO532.0eV:on-topNO530.6eV:hcp+fccNONOexposure:notSaturationSaturationCoverageCoveragewascalculatedusingO1sintensitywithrespecttothatofc(4x2)-CO/Pt(111)(CO=0.5ML)SurfaceSurface[Metka,etal,Z.[Metka,etal,Z.Phys.Chem.,214(6)(2000)StructureStructure[Matsumotoetal.,Surf.Sci.at110at110Pt0.004.79BindingEnergyBPtS11070.6eV,71.0eV,T71.2eV,71.5eV,71.7eV,012NOexposure34Surfacecore-levelshifts—PtIntensity[Zhu,[Zhu,etal,Surf.Sci.529(2003)=0.2=0.2O=0.2N

BindingEnergy

BindingEnergy

NOdissociationdoesnottake PtPt=0.4BindingEnergyHeatingrate:2Heatingrate:0.2ONHeatingrate:0.2Heatingrate:0.4K/sPtHS2TH1TemperatureIntensityTP-XPSandIntensitySummaryofThreesites,namelyfcchollow,on-topandSummaryofsites,canbepopulatedsequentiallybyThestructuremodelofMatsumotoetalis0.25ML,(2x2)-NO,0.25ML<0.5ML,(2x2)-2NO,fcc+on-0.5ML<0.75ML,(2x2)-3NO,fcc+on-Thenatureofthedesorptionpeakat200K:hcp dissociationofNOduringuptakeand Oh=650800500300250200150OxygenIntensityO/Pt(111)O/Pt(111)DoseO2oncleanPt(111)at110annealto300530.5eV:chemisorbedmolecularO2529.7eV:disorderedatomic529.9eV:ordered(2x2)atomicO,Ooccupiesthefcchollowsites.[Matereretal.,Surf.Sci.325(1995)207]OOhcpatomicT=110T=250Intensityatomicatomic110K:shifttolowerBE~0.25250K:noshiftOinitiallypopulatestheon-topadsorptiononthefcchollowsiteshinderedbyatomiccanpopulatethehcphollowsites110KandhighJ.F.J.F.Zhu,etal.,Surf.Sci.547(2003)OOOfcccleanPt(111),1100.25MLO/Pt(111),1100.20MLO/Pt(111),250 hcp(+fcc)on-topatomicBEofatomic012NOexposure34IntensityO1sintenistyBindingEnergyFittingparametersBindingEnergyNOcoverageNOcoveragevsO NOsaturationcoverageLinearfit PrecoveredOcoverageStickingStickingNONOtotalcoverageStickingcoefficientS0StickingcoefficientS0=0.96onPt(111),S0=0.88on(2x2)-O/Pt(111).AdsorptionthroughNOcoverage

ExposureNOtotalcoverage:NOtotalcoverage:reducedlinearlywithOpre-coverageforO0.25MLfccfccHeatingrate:0.2hcp(+fcc)on-topatomicBEofatomicTP-XPSandOO1sintensityBindingBindingEnergy

Temperature

TPD:TPD:NO/(2x2)-Heatingrate:2NOexposure20.25ML0.25MLOalowerdesorptiontemperatureofhcpNO(145Kvs.190K)largeattenuationof2state(fccNO)nochangeof1state(on-topNO).noNOoxidation:NO(a)+O(a)→ThehcpNOtheO1sBEshiftofatomicStructureStructureandOOatomeffectsonOatomeffectsonNOStericsite-blockingSubstratemediatedelectronicIntensityIntensityCoverageT=200CT=200Cnew Exposurenewon-- T=200PeakPeak531.1eV:Bridge532.0eV:on-topNO530.3eV:fccNODoniach-SunjicfunctionsParametersareusedthesameasindividualbridgebridgeCOon-topCOP=4x10-fccNOfcc+hcpNObridgeCOon-topNOon-topCOO01234567NOexposureCNO/0.22MLCO/Pt(111)@110noCOislandthenewstate(CO)growsnoCOreplacementbyinitiallypopulatesthefccsubsequentlypopulatestheon-topandhcphollowsitesalmostthetotalcoverage(NO+CO)atsaturationcoverageis~0.65TotalT=110on-topbridgeTotalT=110on-topbridge =4x10-8024NOexposure68COon-topopensymbol:O1sfilledsymbol:CNO/c(4x2)-CO/Pt(111)(CO=0.5CoverageBridgeCOpartiallyconvertsCoveragetotalOon-topbridgeTtotalOon-topbridgeT=250PNO=1x10-fccon-top0NOexposureCoverageNotemperaturedependenceNOonc(4x2)-NOonc(4x2)-c(4x2),E=105

NONOTPXPSNO/c(4x2)-TPXPSNO/c(4x2)-CoverageCoverage

fccNObridgeCOon-topNOon-topopensymbol:pureCO,1.0

N1sHeatingrate:0.4Heatingrate:0.4

bridgeCOon-toptotal

COonon-topsitesbridgesites,whenNOstartstodesorb.Tdes,NO<Tdes,pure

filledsymbol:

C

Tdes,CO=Tdes,pure

Startingfrom7.5LNOadsorptionatStartingfrom78LNOadsorptionat250Startingfrom8.5LNOadsorptionat110CO0.0700.0 onlyasmallamountofCOcanbeadsorbed.~1100LCOdisplacementisCP=1.1x10-6 COadsorptionC

CO/(2x2)- CO/(2x2)-on-topon-topCP=4x10-8bridgeOfccon-topon-topbridge COexposureCOads.ontheon-COC1speak10LCONOdisplacedby~CoverageIntensityIntensityTPXPSTPXPSofCO+(2x2)-NO/Pt(111)(NO=0.3CoverageCoverage

CONHeatingRate:0.4

bridgeCOon-topfccNObridgeCOon-topNOon-toptotal

FurtherprovesnoreactionFurtherprovesthatNObehaveslikeCOintheCO-NOmixedlayer,withstrongrepulsiveinteractionbetweenCOandNO.WhenNOstartstodesorb,highcoverageCOcharacteristicpeak(CO)graduallyvanishes.Atthesametime,COconversionbetweenon-topsitesandbridgesitestakesplace.TheNOandCOdesorptiontemperaturesinTPXPScoincidewithTPDverywell[R.J.Gorteand Temperature

L.D. idt,Surf.Sci.111(1981)PCOPCO=1.0x10on-topfccbridgeon-top0COexposureO 0.25CO/(2x2)-CP=1.0x10-6 OPfccNO0 COexposureCoverageCO/NO/Pt(111)@250CO/NO/Pt(111)@250CO NOcanbesuccessivelyby on-topCOdisplaceson-topNO,bridgeCOdisplacesfccNO;theformeroccursfirst.CoverageCoverageCoverageCoverageC T=250PCO=1.0x10C T=250PCO=1.0x10bridgeCOon-top-P=1.1x10-6bridgeCOon-top COexposure COdosingtimeThedesorptionofNOandadsorptionofCOarebothrate-determiningSummaryofStrongrepulsiveinteractionbetweenCOSummaryofNopost-adsorptionofNOinducedCOislandformation.Thepost-adsorbedCOcandisplacethepre-dosedNOThedisplacementspeedofNObyCOisdependentonthesampletemperatureandtheCOpressure.ThehigherthesampletemperatureandCOpressure,thefastertheNOintheNO-COmixedlayerbehaveslikeNoreactionbetweenNOandCOtakesplaceuponIn-situXPSIn-situXPS–reaction-CO

O2CoverageO2Coveragereactionorder~(Islandedges,J.Wintterlinetal.,278(1997)

ArrheniusplotArrheniusplotEa=0.470.12eV,=2·10(51)s-

TTS=275K,pCO=110-6COC