资源描述：
《2010Coddington_Time-domain spectroscopy of molecular free-induction decay in the infrared英文学习材料》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、May1,2010/Vol.35,No.9/OPTICSLETTERS1395Time-domainspectroscopyofmolecularfree-inductiondecayintheinfrared1,211,3IanCoddington,WilliamC.Swann,andNathanR.Newbury1NationalInstituteofStandardsandTechnology,325Broadway,Boulder,Colorado80305,USA2ian@boulder.nist.gov3nnewbury@boulder.nist.go
2、vReceivedNovember23,2009;revisedFebruary18,2010;acceptedMarch2,2010;postedMarch25,2010(Doc.ID120276);publishedApril26,2010Time-domainspectroscopyusingdual,coherentfrequencycombsisusedtomeasurefree-inductiondecayfromamoleculargassampleinthenear-IRwithatime-domainsignal-to-noiseratioof
3、106overa6nswindowat55fstimeresolution(correspondingtothe9THzsourcebandwidth)andafrequency/timingac-curacysetbythefrequencycombs.Thefree-inductiondecayexhibitstheexpectedperiodicpulsesfromtherephasingofthemultiplyexcitedrovibrationallevels.ThisdemonstrationrepresentstheÞrsthigh-resolu
4、tion,high-accuracy,broadbandmeasurementofopticalfree-inductiondecay,toourknowledge.OCIScodes:320.7100,140.4050,120.6200.Ashortlightpulsewillexciteresonantmoleculareralways.First,theuseoflasersallowsforlongin-transitionsinasamplethatthenactasoscillatingdi-teractionpaths.Second,inthecon
5、Þgurationwherepoles.Aftertheinitialexcitation,thesedipoleele-onlyonecombpassesthroughthesample,theinter-mentswillcontinuetooscillatecoherently,givingriseferogramisonesided,asindispersiveFTS,rathertocoherentforward-scatteredradiationorfree-thanthetypicaldouble-sidedFouriertransformin-i
6、nductiondecay(FID),whichcanbethoughtofasthefraredinterferogram.Thisone-sidedinterferogramimpulseresponsefunctionofamoleculargas.Thereßectsthecausalityofthesignalandresultsinaforward-scatteredÞeldisinexactlythespatialmodefrequency-domainsignalwithboththephaseandtheoftheincidentpulse,an
7、dtheoverlapwiththeinci-amplitudeinformation.Third,theresolutionissetbydentÞeldyieldsthestandardintensityabsorptionthecombrepetitionrates(evenÞnerifthecombsarespectrumobservedinopticalspectroscopy.Ashasscanned)ratherthanaphysicaldelayline.Fourth,beenwidelydemonstratedinmicrowaveandtera
8、-thef
