第三章nmr实验技术基础

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1、granmr06.doc第三章NMR实验技术基础1NMR仪器如图，现代超导核磁谱仪的主要组成部分包括：1.超导磁体Magnet包括FieldLock，ShimCoils2.探头Probe内有RFCoils，GradientCoils3.脉冲编程器及射频放大器4.接收器5.数据采集及处理计算机Atthetopoftheschematicrepresentation（图示）,youwillfindthesuperconductingmagnetoftheNMRspectrometer.Themagnetprod

2、ucestheBofieldnecessaryfortheNMRexperiments.ImmediatelywithintheboreofthemagnetaretheshimcoilsforhomogenizingtheBofield（匀场）.Withintheshimcoilsistheprobe.TheprobecontainstheRFcoilsforproducingtheB1magneticfieldnecessarytorotatethespins.TheRFcoilalsodetectst

3、hesignalfromthespinswithinthesample.ThesampleispositionedwithintheRFcoiloftheprobe.Someprobesalsocontainasetofgradient（梯度）coils.ThesecoilsproduceagradientinBoalongtheX,Y,orZaxis.Gradientcoilsareusedforforgradientenhancedspectroscopy,diffusion,andNMRmicrosc

4、opyexperiments.图示的顶端是NMR谱仪的超导磁体。它产生NMR实验必需的Bo场。超导磁体的核心是用于匀场的垫片线圈。其中有探头，包括产生用于旋转的B1电磁场的RF线圈。RF线圈同样探测样品的旋转信号。样品由此定位。一些探头中包含一系列的梯度线圈。这些线圈在Bo沿X，Y，Z方向产生梯度场。梯度线圈是被用来产生加强光谱，散射和其他NMR微尺度实验的梯度的。Theheartofthespectrometeristhecomputer.Itcontrolsallofthecomponentsofthe

5、spectrometer.TheRFcomponentsundercontrolofthecomputeraretheRFfrequencysourceandpulseprogrammer.Thesourceproducesasinewaveofthedesiredfrequency.Thepulseprogrammersetsthewidth,andinsomecasestheshape,oftheRFpulses.TheRFamplifier（扩音器）increasesthepulsespowerfro

6、mmilliWattstotensorhundredsofWatts.Thecomputeralsocontrolsthegradientpulseprogrammerwhichsetstheshapeandamplitudeofgradientfields.Thegradientamplifierincreasesthepowerofthegradientpulsestoalevelsufficienttodrivethegradientcoils.Theoperatorofthespectrometer

7、givesinputtothecomputerthroughaconsoleterminalwithamouseandkeyboard.Somespectrometersalsohaveaseparatesmallinterfaceforcarryingoutsomeofthemoreroutineproceduresonthespectrometer.Apulsesequenceis12granmr06.docselectedandcustomizedfromtheconsoleterminal.Theo

8、peratorcanseespectraonavideodisplaylocatedontheconsoleandcanmakehardcopiesofspectrausingaprinter.频谱仪的核心是计算机。它控制着频谱仪的所有组件。被计算机控制的RF组件是RF频率源和脉冲程序。源负责产生需求频率的正弦波，脉冲程序则设置RF脉冲的宽度，某些情况下也设定形状。RF放大器把脉冲能量从百万分之一瓦特放大到几十甚