NMR核磁共振初学者手册（英文版）_127页.pdf

VersionAVANCESGU Based Frequency GenerationBeginners GuideEnglish Version003The information in this manual may be altered without notice.BRUKER accepts no responsibility for actions taken as a resultof use of this manual.BRUKER accepts no liability for any mis-takes contained in the manual,leading to coincidental damage,whether during installation or operation of the instrument.Un-authorized reproduction of manual contents,without writtenpermission from the publishers,or translation into another lan-guage,either in full or in part,is forbidden.This manual was written by:Eamonn ButlerThis manual was desktop published by:Stanley J.Niles December 12,2003:Bruker Biospin GmbHRheinstetten,GermanyP/N:Z31633EDWG-Nr:1344003English Version 003iii ContentsContents.iii1Introduction.71.1 Sources of Hazards.7Software Version and Command Syntax.82Safety.92.1 Introduction.92.2 Magnetic Safety.9Safety Precautions within the Inner Zone.10Safety precautions within the outer zone.112.3 Cryogenic Safety.112.4 Electrical Safety.112.5 Chemical Safety.122.6 CE Certification.123Introductory Theory and Terminology.133.1 Introduction.133.2 NMR Analysis of Chloroform.163.3 Reference Compounds,Hertz,ppm.173.4 Proton NMR-Chemical shift.193.5 Proton Spectrum of Benzene.203.6 Proton Spectrum of Benzylacetate.213.7 Proton Spectrum of Ethylbenzene with Spin/Spin Coupling.223.8 Decoupling.253.9 FID and Spectrum.264System Description.294.1 Introduction.294.2 Operator Console and Connections.304.3 Console.304.4 Link Between the Host Computer and the AQS.314.5 Magnet,Shim System,HPPR and Probe.314.6 The Magnet and Magnet Dewar.33Room Temperature Bore.34Helium Tank.35Nitrogen Tank.364.7 Introduction to the Lock System.364.8 Probes.37Dual 13Cl1H probe.39Changing a Probe.41iv English Version 003Contents5The NMR Sample.435.1 Introduction.435.2 Solvent Selection.435.3 Sample Tube.445.4 Sample Handling.456Basic procedures.476.1 Introduction.476.2 BSMS Keyboard.47Storing a Set of Shim Values(Write Shim Command).48Reading a Stored Shim File(Read Shim Command).49BSMS Functions.49Sample Control Functions.49Manual Lock Functions.50Manual Shim Functions.50Helium Level Functions.516.3 Inserting the Sample into the Spinner.516.4 Inserting the Sample Plus Spinner into the Magnet.526.5 Spinning the Sample.536.6 Tuning and Matching the Probe.53Tuning and Matching Using the Wobble Curve.54Tuning and Matching Using the HPPR LEDs.56Tuning and Matching More than One Nucleus.576.7 Locking the Sample.58Procedure to Lock the Sample.596.8 Shimming.61Initial Shimming.62Routine Shimming.627Preparing for Acquisition,Data Sets,edasp/eda Commands.657.1 Introduction.657.2 Data Sets.657.3 Creating a Data Set.677.4 Spectrometer Parameters edasp.68Layout of the edasp Window.70Some Features of the edasp Window.727.5 Basic Acquisition Parameters:The“eda”Table.72Numerical Explanation of Transmitted,Basic and Offset Fre-quencies.798Pulse Programs/Command ased.838.1 The Pulse Programs“zg”and“zg30”.838.2 Details of the“zg30”Program.838.3 The Command“ased”.869Proton Spectrum.879.1 Introduction.879.2 Creating a New Data Set.87ContentsEnglish Version 003v 9.3 Reading in the Standard Parameter Set.88The“getprosol”table.889.4 Setting the Receiver Gain.889.5 Starting the acquisition.909.6 Fourier Transform and phase correct the spectrum.919.7 Basic Processing:Fourier Transformation.939.8 Phase Correction.949.9 Calibration of Spectrum.95Procedure to Expand the Spectrum Horizontally.96Calibration Procedure.969.10 Adjusting the Spectral Width with the SW-SFO1 function.97Adjusting the SW for Cholesterylacetate Spectrum.989.11 Increasing the number of scans.991013C Spectrum without decoupling.10110.1 Introduction.10110.2 Procedure.1011113C spectrum with decoupling.10511.1 Introduction.10511.2 Procedure.10511.3 Establishing the Decoupling Frequency.10611.4 Adjusting the Decoupling Parameters.10811.5 The pulse program zgpg30.10912Basic Troubleshooting.11312.1 Introduction.11312.2 Switching the Spectrometer On and Off.11312.3 Switching on the Spectrometer.11412.4 Switching off the Spectrometer.114Starting Topspin for Windows Systems.114Figures.115Tables.117Index.119vi English Version 003ContentsEnglish Version 0037(127)1Introduction1 The goal of this manual is to enable a relatively inexperienced user to carry out aseries of basic 1-D High Resolution(HR)NMR experiments.Cholesterylacetatewas chosen as an example.Both proton observe and carbon observe(with andwithout proton decoupling)will be described.To assist the user standard parame-ter sets delivered with every Topspin software package will be used.However,rather than simply reading in standard parameter sets,a genuine effort has beenmade to help the user understand the relevance of the various parameters.In par-ticular,this manual will concentrate on describing the acquisition procedure,tosome extent,at the expense of processing the acquired data.This emphasis min-imizes the time spent on the actual spectrometer itself,particularly in the casewhere relatively large numbers of undergraduate students are being trained.Inthis scenario processing can be easily carried out on a separate workstation usingthe tutorials delivered with the spectrometer documentation.For the purpose of instruction within this manual it is assumed that the user has:1.A basic knowledge of the Topspin software package;2.A probe or probes capable of observing proton,observing carbon and observ-ing carbon while decoupling protons;3.A basic knowledge of how to operate the BSMS keyboard or the BSMS controlpanel.While every effort has been made to genuinely provide a step by step description,new users will invariably have some questions,and as such will require occasion-al assistance from a more experienced user.The goal of this manual is,wherepracticable,to enable users to work independently and acquire a basic under-standing of how to operate the system.It is hoped that the time taken to train newusers will be significantly reduced with the use of this manual.Sources of Hazards1.1The following chapter will deal with safety in detail,but for now it is worth highlight-ing potential hazards that arise when operating an NMR spectrometer at this intro-ductory stage.For such a sophisticated system there are surprisingly fewopportunities for inexperienced users to damage the equipment,so few that themost important ones are worth itemizing.With normal operation the most likelycauses of damage are:1.Removing a sample from the magnet with the bore still plugged;2.Inserting a sample into the magnet without the presence of the supporting aircushion;3.Emitting RF pulses that are either too long,too powerful or both;4.Transmitting RF power along unconnected cables or poorly matched probes.8(127)English Version 003IntroductionNew users are advised to acquaint themselves with these potential hazards be-fore commencing.System managers are advised to ensure that any new usersunderstand the issues mentioned above.Software Version and Command Syntax1.1.1This manual has been written for Topspin version 1.1.Throughout the manualprocedures to enter various commands will be outlined.The command to betyped will be in single quotes using magenta colored text.For example,enter edameans type the command eda at the command line and press the Return“orEnter“button.English Version 0039(127)2Safety 2 Introduction2.1In terms of safety the presence of a relatively strong magnet is what differentiatesNMR spectrometers from most other laboratory equipment.When designing anNMR laboratory,or training personnel who will work in or around the laboratory,no other feature is of greater significance.As long as correct procedures are ad-hered to,working in the vicinity of superconducting magnets is completely safeand has no known harmful medical side effects.Negligence however can result inserious accidents.It is important that people working in the vicinity of the magnetfully understand the potential hazards.Of critical importance is that people fit-ted with cardiac pacemakers or metallic implants should never be allowednear the magnet.The magnet is potentially hazardous due to:1.The large attractive force it exerts on ferromagnetic objects.2.The large content of liquid nitrogen and helium.Magnetic Safety2.2A magnetic field surrounds the magnet in all directions.This field(known as thestray field)is invisible and hence the need to post warning signs at appropriate lo-cations.Objects made of ferromagnetic materials,e.g.iron,steel etc.will be at-tracted to the magnet.If a ferromagnetic object is brought too close,it maysuddenly be drawn into the magnet with surprising force.This may damage themagnet,or cause personal injury to anybody in the way!Because the strength of the stray field drops significantly as one moves awayfrom the magnet,it is useful to discuss safety in terms of two broadly defined re-gions,the inner and outer zone.In terms of organizing a laboratory as well as de-fining good work practices,the concept of an inner and outer zone is particularlyuseful.The physical extent of these two zones will depend on the size of the magnet.Thebigger the magnet,the stronger the stray magnetic fields and hence the larger theextent of the two zones.Figure 2.1.shows the concept of the two zones(notdrawn to scale).Details of stray fields for various magnets can be found in the SitePlanning Guides delivered with the BASH CD.10(127)English Version 003SafetyFigure 2.1.Safety Precautions within the Inner and Outer Zones Safety Precautions within the Inner Zone2.2.1The inner zone extends from the magnet center to the 1mT(10 Gauss)line.With-in this region objects may suddenly be drawn towards the magnet center.The at-tractive force of the magnet can change from barely noticeable to uncontrollableCryogenic SafetyEnglish Version 00311(127)within a very short distance.Under no circumstances should heavy ferromag-netic objects be located or moved within this zone.Any ladders used when working on the magnet should be made of non-magneticmaterial such as aluminum.Helium and nitrogen dewars which are used to top upthe liquid levels inside the magnet must be made of non-magnetic material.Do not allow small steel objects(screwdrivers,bolts etc.)to lie on the floor nearthe magnet.These could cause serious damage if drawn into the magnet bore,especially when no probe is inserted in the magnet.Mechanical watches may be damaged if worn within the inner zone.Digital watch-es can be worn safely.Of course,the precautions for the outer zone which willnow be discussed must also be adhered to within the inner zone.Safety precautions within the outer zone2.2.2The outer zone extends from the 1mT line to the 0.3mT line.The magnetsstray field does not get blocked by walls,floors or ceilings and the outer zone maywell encompass adjoining rooms.The stray field may erase information stored onmagnetic tapes or discs.Bank cards,security passes or any devices containing amagnetic strip may be damaged.CDs will not be damaged,although CD drivesmay contain magnetic parts.When using pressurized gas cylinders made of steel,they should be located well beyond the outer zone(preferably outside the magnetroom)and must always be properly fixed to the wall.The color display of comput-er monitors may suffer some distortion when located too close to the magnet,al-though permanent damage is unlikely.Once beyond the outer zone any specialprecautions on account of the magnet stray field are no longer necessary.Cryogenic Safety2.3The magnet contains relatively large quantities of liquid helium and nitrogen.These liquids,referred to as cryogens,serve to keep the magnet core at a verylow temperature.Because of the very low temperatures involved,gloves,a long sleeved shirt orlab coat and safety goggles should always be worn when handling cryogens.Di-rect contact with these liquids can cause frostbite.The system manager shouldregularly check and make sure that evaporating gases are free to escape from themagnet,i.e.the release valves must not be blocked.Do not attempt to refill themagnet with helium or nitrogen unless you have been trained in the correct proce-dure.Helium and nitrogen are non-toxic gases.However,because of a possible mag-net quench,whereupon the room may suddenly fill with evaporated gases,ade-quate ventilation must always be provided.Electrical Safety2.4The spectrometer hardware is no more or less hazardous than any typical elec-tronic or pneumatic hardware and should be treated accordingly.Do not removeany of the protective panels from the various units.They are fitted to protect you12(127)English Version 003Safetyand should be opened by qualified service personnel only.The main panel at therear of the console is designed to be removed using two quick release screws,butagain,this should only be done by trained personnel.Please note that,unless dis-connected,cooling fans on the rear panel will continue to run even with the panelremoved.Chemical Safety2.5Users should be fully aware of any hazards associated with the samples they areworking with.Organic compounds may be highly flammable,corrosive,carcino-genic etc.CE Certification2.6All major hardware units housed in the AVANCE with SGU consoles as well asperipheral units such as the HPPR,shim systems,probe and BSMS keyboardscomply with the CE Declaration of Conformity.This includes the level of any strayelectromagnetic radiation that might be emitted as well as standard electrical haz-ards.Note that to minimize electromagnetic radiation leakage,the doors of theconsole should be closed and the rear paneling mounted.English Version 00313(127)3Introductory Theory and Terminology3 Introduction3.1NMR is a technique used to analyze the structure of many chemical molecules,primarily organic compounds.A typical compound might consist of carbon,hydro-gen and oxygen atoms.In its simplest form,an NMR experiment consists of three steps:1.Place the sample in a static magnetic field.2.Excite nuclei in the sample with a radio frequency pulse.3.Measure the frequency of the signals emitted by the sample.Figure 3.1.Excitation and Response From the emitted frequencies analysts can deduce information about the bondingand arrangement of the atoms in the sample.The NMR active nuclei in the sam-ple resonate at different frequencies which are called resonance frequencies“.These are the frequencies emitted by the nuclei when they are excited by the in-coming radio frequency pulse.The value of a resonance frequency depends ontwo factors:a)Type of Nucleus:Every isotope has a particular combination of protons and neutrons in its nucleus.The nuclear structure largely determines the value of the resonance frequency.Thus every isotope displays a“basic resonance frequency”.13C nuclei will have adifferent basic resonance frequency compared to that of 1H etc.Note the largevariation in basic resonance frequencies between different isotopes as listed inTable 3.1.14(127)English Version 003Introductory Theory and Terminologyb)Local Atomic Environment: