核磁共振常用技术术语.pdf

《核磁共振常用技术术语.pdf》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、TerminologyCommonlyUsedinNMRSpectroscopyabsoluteintensityAdisplayorplotmodeinwhichthesignalintensityisproportionaltotheconcentrationofthespeciesproducingit.acquisitiontimeTimeduringwhichsignalisrecorded(seefigure1).FIDDeadtimeAcquisitiontimeFigure1.Signalisac

2、quiredinthetimedomain.attenuationThecontrolappliedtovoltages(includingsignalfromthesample)withinthespectrometer.Highattenuationgiveslow-voltage,low-attenuationgiveshigh-voltage.B0Thestaticmagneticfield.Themagneticfluxdensityisexpressedintesla,T,oroften,asaneq

3、uivalent1Hresonancefrequency(forexample,300MHzfora7Tmagnet).B1Magneticfieldassociatedwitharadio-frequency(r.f.)pulse.OftenexpressedasanequivalentvalueinkHz.bandshapeUsuallyusedwhenreferringtoacomplexlineshapeoragroupofoverlappinglines.Complexbandshapesoftenar

4、isefromquadrupolarnuclei(seefigure2).centrebandThesignalattheisotropicchemicalshift.Itspositionisthesameatallspin-rates.Figure2.BandshapefromachannelTheindividualfrequenciesorfrequencybandssingle11Benvironment.ofaspectrometer.Forexample:H-channel(proton),C-ch

5、annel(carbon)orbroad-band(orX)channel(usuallyanythingexceptH).chemicalshiftNumberusedforreportingthepositionofaline(ni)n-nrelativetoareferenceline(nref)inahigh-resolutiond=iref´106spectrum.Thechemicalshiftparameterisdenotednrefdandquotedinppm.coherencepathway

6、Descriptionofanexperimentthatallowstheexcitationofthespinstobefollowed.Usefulforexperimentswhereexcitationorselectionofsignalfromone-,two-ormultiple-quantumtransitionsisneeded.contacttimeTimeduringwhichtwomatchedradio-frequencyfieldsareappliedsimultaneouslyin

7、aCPexperiment.CPCross-polarisation.Anyexperimentwhereenergy(magnetisation)istransferredfromthenucleiofoneelement(oftenH)tothoseofanother.dead-timeTimebetweenapulseandtheswitchonofthereceiver.Thespectrometercircuitryneedstimetosettleaftertransmittingthehighvol

8、tageassociatedwithapulsebeforeitcandetecttheverylowvoltageassociatedwiththesignalfromthesample.Seefigure1.1©Solid-stateNMRService2001d.c.offsetConstant-valueoffsetoccurringintheFID(see“Pr