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ID:40105109
大小:4.47 MB
页数:121页
时间:2019-07-21
《Time-harmonic electromagnetic fields in chiral medium》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、1.INTRODUCTIONAtthebeginningofthelastcentury,thephenomenonofopticalactivityincertainbiologicalandmineralsubstanceswasdiscoveredindependentlybyArago[1811]andBiot[1812,1815,1817].Condensedmattertheorieswerestillinembryonicstagesatthattime.Assuch,itisremarkablethatPasteur[1848,1850]interpretedBlot'sob
2、servationsbyimaginingthatthearrangementofatomswithinanopticallyactivematerialisasymmetricinhavinganon-superposablemirrorimage;i.e.,thisarrangementishandedorchiral.AnothertwentyoddyearshadtoelapseforPasteurtobevindicatedbythesimultaneousproposalsofthetetravalentcarbonatombyvan'tHoff[1874]andLeBel[18
3、74].Notonlydidthesediscoveriesrequiretheidentificationofthatpropertyoftheopticallyactivesubstanceswhichcausesrotationofpolarizedlight,buttheyalsoforcedthethenscientificestablishmenttoenquiremorevigorouslyintothenatureoflight.In1819,Fresnel[1866]hadbeenabletoshowthattheeffectsofpolarizedlightcouldbe
4、explainedbythehypothesisthatlightwasatransversewave.Withadvancesinelectromagneticfieldtheorywhichprovedthatlightwasindeedanelectromagneticwave,thefieldofstereochemistryexpandedradicallyandhasprovidedinsightsintothestructureofmoleculesand,indeed,intothenatureoflife.Foraninterestinghistoricaldevelopm
5、entofthisareainthe19thcentury,arecentreviewbyApplequist[1987]isrecommended.Achiralmediumischaracterizedbyeitheraleft-handednessoraright-handednessinitsmicrostructure.Asaresult,inachiralmediumleft-andright-circularlypolarized(LCPandRCP)fieldspropagatewithdifferentphasevelocities:thefieldwiththelatte
6、rpolarizationtravelingthrougharight-handedmediumfasterthantheleft-circularlypolarizedfield,andviceversa.Opticalactivity,whichisexhibitedbyamultitudeoforganicmoleculesatopticalfrequencies,isamanifestationofthenativechiralityofthesemolecules[Eyringetal1944;Charney1979;Barron1982].Thetwinphenomenaofci
7、rculardichroism(CD)andopticalrotatorydispersion(ORD)areobservedwhenalinearly-polarizedplanewavetravelsthroughasuspensionofchiralmolecules.ORDreferstotherotationoftheplaneofpolarizationofthetransmittedplanew
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