固体催化剂研究方法――第十五章 电子顺磁共振方法(下)

(),(,310027)3-,-/-,-(Electronucleardoubleresonance,EN2DOR)[83],EN2DOR,3.1-[84]Hooho=gHooLarmor,EPRHoo,,Larmer,-3.1.1S=I=1/2ENDORS=I=1/2,Ho(I=1/2),1111S=I=1/2Fig.11Energylevelsplittingdiagramofnon-pairelectron(S=1/2)momentumintheappliedfieldunderinteractionwithcircularmagneticnuclei(I=1/2).·=gHS+gnnHI+a’IS·|mS,mI,E(MS,MI)=-gMSH-gnnMIH-a’MSMIE1=E(+1/2,+1/2)=-12gH-12gnnH-’/4E2=E(+1/2,-1/2)=-12gH+12gnnH+’/4E3=E(-1/2,+1/2)=+12gH-12gnnH+’/4E4=E(-1/2,-1/2)=+12gH+12gnnH-’/4ENDORMS=0,MI=1ENDORE1=(E4-E3)/h=gnnH/h-1/2a’/h=n-A/2E2=(E2-E1)/h=gnnH/h+1/2’/h=n+A/2A=a’/h,a(1001MHz)0(1001GHz)3ENDOR,0Ho,=na/2ENDOR(nLarmor)12na/2,E1E20,ENDOR()n/2,E10,1ENDORn,naENDOR,,NMR(na/2),,EPR,NMR,,=n-a/2,E3E4,E1E3,,EPR3.1.2S=1/2I=1ENDORS=1/2I=1,14N14NI=11/2,Q,(13)1042002315PETROCHEMICALTECHNOLOGY©1995-2005TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.12S=1/2I=1/2ENDOR12Fig.12ENDORsignalposition1,2ofS=1/2,I=1/2system.13S=1/2I=1Fig.13EnergylevelsplittingdiagramofS=1/2,I=1systeminappliedfieldandinteractionwithmagneticnuclei.·=gHS+gnnHI+a’IS+IQ’IE(MS,MI)=-MSgH-MIgnnH-a’MIMS+[MI2-I(I+1)/3]Q’ENDORE=n12A32QA=2a’/h;Q=2Q’/3h,4ENDOR14(a)14S=1/2I=1n(+3Q)/2ENDORFig.14ENDORsignalpositionofS=1/2,I=1systemwhenn(a+3Q)/2.(c)A3QA3QA=3QENDORn(A+3Q)/2,144,Qa,n(A+3Q)/2,43.1.3ENDOR,ENDOR,ENDOR,,[85],ENDOR,EPR,,gxxgyygzzHxxHyyHzzo,ENDOR,ENDORAxxAyyAzz,gzz=g;gxx=gyy=g,gHENDOR,ENDORENDOR(15a)gENDOR,xy,ENDOREN2DOR(15b)15ENDOR(a);(b)Fig.15ENDORspectraofdisorderedsystem.(a)Singlecrystalliketype;(b)Powdertype3.1.4ENDOR[86]ENDORENDOR,,D-ENDOREI-EPRCP-ENDORPM-ENDOR,3.1.4.1ENDOR(D-ENDOR)S=1/2I1=I2=1/2,A1A2,[87]ENDORD-ENDORHamiltoian:·=gHS-gnnHI+A1I1S+A2I2SI=I1+I2,4ENDOR204PETROCHEMICALTECHNOLOGY200231©1995-2005TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.MI,2=1,hn1=gnnH-A2/2;MI,1=1,hn2=gnnH-A2/2;MI,1=1,hn3=gnnH+A2/2;MI,4=1,hn4=gnnH+A2/23.1.4.2ENDOR(EPR)ENDOREPRENDOREPRENDORSchweiger[88]EI-EPRENDOR,,16(a)Cu(acacen)Ni(aca2cen)EPR[89],acacen4,5,4316(b)16Cu(acacen)Ni(acacen)EPR(a)IE-EPR(b)Fig.16EPRspectrumandIE-EPRspectrumofCu(acacen)asadopantintosinglecrystalofNi(acacen).EI-EPR[88],4,517[89]V(bz)2EPR(a)EI-EPR(be),vHAmax/2(b)=8.50Mz;(c)=8.70Mz;(d)=8.75Mz;(e)=8.80Mz17(c)51V(I=7/2)817V(bz)2EPR(a)EI-EPR(be)Fig.17EPRspectrumofV(bz)2powdersampledilutedintoferrocene(a)andsinglecrystallikeEI-EPRspectrum(be).EI-EPR,EI-EPR[89]3.1.4.3ENDOR(CP-ENDOR)ENDOR,Hx(t)=iHx0costHy(t)=iHy0=cos(t+)Hx0=Hy0=H2=90,=-90H,TE11218(a)Cu(biyam)2(ClO4)2Zn(biyam)2(ClO4)2(20K),ENDOR;(b)CP-ENDOR18,[90]3.1.4.42ENDOR(PM-ENDOR)-ENDOR,H2xyrnmmPM-ENDORm18Cu(biyam)2(ClO4)2Zn(biyam)2(ClO4)2ENDOR(a)CP-ENDOR(b)Fig.18NormalENDOR(a)andCP-ENDOR(b)spectrumofCu(biyam)2(ClO4)2asadopantintosinglecrystalofZn(biyam)2(ClO4)2.3.2ENDORENDORr-6,EN2DOR0.50.6nm[90],ENDOR3.2.11961Rooney[91]EPRLewisDollish[92]1967Bronsted1968[93],1969,Garret[94],EPR0.8%27Al3+,Muha[95,96]3045:()©1995-2005TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.,,,[97]1980,Clarkson[98]ENDOR-O-23,Flockhart[99],Lewis:,EPR,EPR,,1982,Wozniewski[100]:EPRBronsted;EPRLewis,(),20Rothenberger[101]ENDORAl2O3SiO2-Al2O3120K14.3MHz3.7MHzENDOR3380G,LarmorH=14.4MHz,Larmor27AlLarmorAl=3.78MHz,3.7MHzENDOR27AlLar2mor,,2.3MHz,LarmorD=2.21MHz,3.7MHz,2.3MHz,1(3),2.3MHzENDORd6-Larmor14.3MHz3.7MHz,d12-ENDOR,1(4)1(4),2.3MHzd12-d6-,LewisLewis,,14.3MHzEN2DORLewis(AlOH)3.7MHz27Al(n3.78MHz)13C(n=3.58MHz),13C1.1%,27Al3.7MHz14.3MHz,(HoudryM-46,90%SiO210%Al2O3),1(5)(7)Al2O3,(),3.7MHzENDOR1(5)14.3MHz,Bronsted,BronstedEN2DOR,,Lewis,,Bronsted,ENDOR,1ENDOR[101]Table1TheENDORspectraoffreeradicalproducedbyadsorptionontheactivationaluminaoraluminumsilicate[101]No.CatalystAdsorbantSolvent14.3MHz3.7MHz2.3MHz(1)Al2O3Pery+C6H6StrongExist(2)Al2O3Pery+C6D6StrongExistExist(3)Al2O3Pery+Vacuumde-gasStrongExist(4)Al2O3d12-Pery+C6D6StrongExistExist(5)HoudryM-46Pery+C6H6Mid-strong(6)HoudryM-46Pery+C6D6VeryweakExist(7)HoudryM-46d12-Pery+C6D6VeryweakExist3.2.2HYENDOR,()EPR[102]--,,[103]EPR2,2,6,6--1-[104],,[105]Samoilova[106]3:(A)AlCl3;(B)HY;(C)HYA140KBEPR,19abc19a62.5G27Al(27AlI=5/2)-Al3+[107]140K,,1314G(19b)BEPR(19c)BHYAl3+,ABCENDOR(20a404PETROCHEMICALTECHNOLOGY200231©1995-2005TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.19EPRa.AEPR;b.A140KEPR;c.BEPRENDORFig.19EPRspectrumofsample.a.EPRspectrumofsampleAmeasuredunderroomtemperature;b.EPRspectrumofsampleAmeasuredunder140K;c.sampleBmeasuredunderroomtemperature.ArrowpositionsarefieldpositionofENDORdetection.bc)ABENDOR(20ab),6.57MHzENDOR,14.5MHzLarmor(H=14.4MHz)CENDORABEN2DOR,13.8MHz19F(19FLarmorF=13.6MHz)27AlEN2DOR,27AlLarmorAl20,Al20ENDORa.A140KENDOR;b.BENDOR;c.C200KENDORFig.20ENDORspectrumofsample.a.ENDORspectrumrecordedunder140KofsampleA;b.ENDORspectrumofsampleB;c.ENDORspectrumrecordedunder200KofsampleC.-27Al27Al19a2.5G(7.2MHz),206.57MHzENDOR,27AlLarmorAl3.4MHz,27AlLarmor27Al(ESEEM),ENDOR,H,LewisESEEM27Al6MHz3.2.3HY,,ESR,,EPREN2DOR[108110]Erickson[108]HYHY,77KX(70kV,20mA)10min377K,HYEPR(,4.55G)6,,g=2.0023g=2.0029[111]3,gA,77K,6,H=4.4G,D=0.70.8G(H/D6.3),25K,63.5K,,,EPRHY21C6H6+/SiO2(a)C6D6+/SiO2(b)110KENDORFig.21ENDORspect