正丙醇和异丙醇的紫外光解动力学

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1、———————————————————————————————————————————————————————————————1003-7713/2002/03-233-4UltravioletPhotodissociationDynamicsof1-Propanoland2-PropanolbyHigh-!Rydberg-atomTime-of-fligh（tHRTOF）Technigue兴ZhouWeidong，ZhangJingsong兴兴（DepartmentOfChemistry，UniuersityOfCal

2、ifOrnia，Riuerside，CA92521）abstract193.3nmphotodissociationdynamicsofet-cooIed1-propanoIand2-propanoIhasbeenexaminedbyusinghigh-nRydberg-atomtime-of-fIight（HRTOF）technigue.IsotopeIabeIingstudyindicatesthatO-HbondfissionistheprimaryH-atomproductionchanneI.Center-of

3、-mass（CM）producttransIationaIenergyreIeaseofthischanneIisIarge，with〈fT〉=0.76forH+1-propoxyand0.78forH+2-propoxy.MaximumCMtransIationaIenergyreIeaseyieIdsanupperIimitoftheO-Hbonddissociationenergy：（43212）kJ/moIin1-propanoIand（43312）kJ/moIin2-propanoI.H-atomproduct

4、anguIardistributionisanisotropic（with!二-0.79for1-propanoIand-0.77for2-propanoI），indi-catingashortexcited-stateIifetime.The193.3nmH-atomdissociationofboth1-propanoIand2-propanoIispromptandoccursonarepuIsiveexcited-statepotentiaIenergysurface.KeywordsPhotodissociat

5、iondynamics，1-propanoI，2-propanoICLCnumber：O64Documentcode：AbeenmeasuredbyDoppIerbroadenedfIuorescenceIine1Introduction［5］shapeofthenascentH-atomsandtheHRTOF［6］，indicatingthatthefirsteIectronicexcit-UItravioIe（tUV）photochemistryofsmaIIsatu-technigueratedaIcohoIsv

6、iathefirstUVabsorptionbands（S1卜edstateofCH3OH（viano一"兴/3s）isrepuIsivein）hasbeenstudiedbefore［1-10］theO-HcoordinateanddissociatesrapidIy.TheS0.TheseUVabsorp-tionbandsarecenteredat185nm；theyarebroad，concIusionisconsistentwiththetheoreticaIstudiesof［8-10］featureIess

7、，andnearIyidenticaI.ThetransitionisduemethanoIphotochemistry.topromotionofaneIectronfromthenon-bonding2p!SimiIarIy，theO-HbondcIeavageisthemainorbitaIontheoxygenatomtoanexcitedorbitaIwhichdissociationchanneIintheUVphotoIysisofethanoI［1-3，6，7］hasbeendescribedaseith

8、eranantibonding"兴（O-viaitsfirstabsorptionband.AIargefractionH）orbitaI，a3sRydbergorbitaIoracombinationofoftheboth（n兴/3s）［11，12］.avaiIabIeenergyischanneIedintotr