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1、Chemicalphysics:Molecularclouds,clusters,andcorralsDudleyHerschbachDepartmentofChemistryandChemicalBiology,HarvardUniversity,Cambridge,Massachusetts02138Vignettesofthreefrontierareasillustratetheeclecticscopeofmodernchemicalphysics.(1)Radioastronomyhasrevealedapr
2、ofusionoforganicmoleculesininterstellarclouds,nowattributedtosequencesofexoergic,bimolecularion-moleculereactionsproceedingfarfromthermodynamicequilibrium.TheorganicprofusionoccursbecauseHe1ionsreactfarmorereadilywithCOthanwiththemuchmoreabundantH2molecules.(2)Mo
3、lecularclusters,generatedbysupersonicexpansions,havebecomeafavoritemediumforstudyofreactionsandspectra.Exemplaryepisodesarethediscoveryofcarbon-60andkindredfullerenemoleculesandtheobservationofsharprotationalspectraofguestmoleculesinsuperˉuidheliumclusters.(3)New
4、meanstocontrolmoleculartrajectoriesarebeingdeveloped.Theseincludespatialorientationoralignmentby?eld-inducedhybridizationofrotationalstates,corralling(ortrapping)moleculesaftercollisionalormechanicalquenchingoftranslationalkineticenergy,andlasercontrolofphotochem
5、icalreactionpathways.[S0034-6861(99)02702-6]I.INTRODUCTIONbodiedprinciplesthattranscendthespeci?csubstances.AchemicalphysicistthussometimesstandsawkwardlyInitsmodernincarnation,chemicalphysicsasa?eldastrideawideningintellectualabyss.However,oftentheisgenerallyreg
6、ardedashavingbeenbornin1933,alongdualityofoutlookprovokesinvigoratingperspectives.withtheTheJournalofChemicalPhysics.Its?rsteditor,ThisarticletakesabrieflookatthreefrontierareasthatH.C.Urey,declaredthat``theboundary...hasbeenoffersuchperspectives.Necessarily,thes
7、evignettesarecompletelybridged...chemistsandphysicistshavebe-idiosyncraticandimpressionistic;onlyafewleadingref-comeequallyseriousstudentsofatomsandmolecules''erencesandreviewscanbecited,andmanyotherfruit-(Urey,1933).AmongotherevangelicalfounderswereP.fulareasare
8、leftoutaltogether.Thechiefaimistoex-Debye,H.Eyring,G.B.Kistiakowsky,I.Langmuir,G.emplifythecharacteristiceclecticstyleofchemicalN.Lewis,L.Pauling,K.S.Pitzer,J.