Understanding NMR Spectroscopy

Dr James Keeler is a Senior Lecturer in Chemistry at the University of Cambridge, and a Fellow of Selwyn College. In addition to being actively involved in the development of new NMR techniques, he is also responsible for the undergraduate chemistry course, and is Editor-In-chief of Magnetic Resonance in Chemistry. Dr Keeler is well-known for his clear and accessible exposition of NMR spectroscopy.

• Preface vPreface to the first edition vi1 What this book is about and who should read it 11.1 How this book is organized 21.2 Scope and limitations 31.3 Context and further reading 31.4 On-line resources 41.5 Abbreviations and acronyms 42 Setting the scene 52.1 NMR frequencies and chemical shifts 52.2 Linewidths, lineshapes and integrals 92.3 Scalar coupling 102.4 The basic NMR experiment 132.5 Frequency, oscillations and rotations 152.6 Photons 202.7 Moving on 212.8 Further reading 212.9 Exercises 223 Energy levels and NMR spectra 233.1 The problem with the energy level approach 243.2 Introducing quantum mechanics 263.3 The spectrum from one spin 313.4 Writing the Hamiltonian in frequency units 343.5 The energy levels for two coupled spins 353.6 The spectrum from two coupled spins 383.7 Three spins 403.8 Summary 443.9 Further reading 443.10 Exercises 454 The vector model 474.1 The bulk magnetization 474.2 Larmor precession 504.3 Detection 514.4 Pulses 524.5 On-resonance pulses 574.6 Detection in the rotating frame 604.7 The basic pulse–acquire experiment 604.8 Pulse calibration 614.9 The spin echo 634.10 Pulses of different phases 664.11 Off-resonance effects and soft pulses 674.12 Moving on 714.13 Further reading 714.14 Exercises 725 Fourier transformation and data processing 775.1 How the Fourier transform works 785.2 Representing the FID 825.3 Lineshapes and phase 835.4 Manipulating the FID and the spectrum 905.5 Zero filling 995.6 Truncation 1005.7 Further reading 1015.8 Exercises 1026 The quantum mechanics of one spin 1056.1 Introduction 1056.2 Superposition states 1066.3 Some quantum mechanical tools 1076.4 Computing the bulk magnetization 1126.5 Summary 1176.6 Time evolution 1186.7 RF pulses 1236.8 Making faster progress: the density operator 1266.9 Coherence 1346.10 Further reading 1356.11 Exercises 1367 Product operators 1397.1 Operators for one spin 1397.2 Analysis of pulse sequences for a one-spin system 1437.3 Speeding things up 1467.4 Operators for two spins 1497.5 In-phase and anti-phase terms 1527.6 Hamiltonians for two spins 1577.7 Notation for heteronuclear spin systems 1577.8 Spin echoes and J-modulation 1587.9 Coherence transfer 1667.10 The INEPT experiment 1677.11 Selective COSY 1717.12 Coherence order and multiple-quantum coherences 1737.13 Summary 1787.14 Further reading 1797.15 Exercises 1808 Two-dimensional NMR 1838.1 The general scheme for two-dimensional NMR 1848.2 Modulation and lineshapes 1878.3 COSY 1908.4 DQF COSY 2008.5 Double-quantum spectroscopy 2038.6 Heteronuclear correlation spectra 2088.7 HSQC 2098.8 HMQC 2128.9 Long-range correlation: HMBC 2158.10 HETCOR 2208.11 TOCSY 2218.12 Frequency discrimination and lineshapes 2268.13 Further reading 2368.14 Exercises 2389 Relaxation and the NOE 2419.1 The origin of relaxation 2429.2 Relaxation mechanisms 2499.3 Describing random motion – the correlation time 2519.4 Populations 2589.5 Longitudinal relaxation behaviour of isolated spins 2639.6 Longitudinal dipolar relaxation of two spins 2679.7 The NOE 2749.8 Transverse relaxation 2869.9 Homogeneous and inhomogeneous broadening 3009.10 Relaxation due to chemical shift anisotropy 3049.11 Cross correlation 3069.12 Summary 3119.13 Further reading 3119.14 Exercises 31310 Advanced topics in two-dimensional NMR 31910.1 Product operators for three spins 32010.2 COSY for three spins 32510.3 Reduced multiplets in COSY spectra 33010.4 Polarization operators 33710.5 ZCOSY 34510.6 HMBC 34710.7 Sensitivity-enhanced experiments 34910.8 Constant time experiments 35310.9 TROSY 35810.10 Double-quantum spectroscopy of a three-spin system 36610.11 Further reading 37410.12 Exercises 37611 Coherence selection: phase cycling and field gradient pulses 38111.1 Coherence order 38211.2 Coherence transfer pathways 38711.3 Frequency discrimination and lineshapes 38911.4 The receiver phase 39111.5 Introducing phase cycling 39511.6 Some phase cycling ‘tricks’ 40111.7 Axial peak suppression 40311.8 CYCLOPS 40311.9 Examples of practical phase cycles 40411.10 Concluding remarks about phase cycling 40811.11 Introducing field gradient pulses 40911.12 Features of selection using gradients 41611.13 Examples of using gradient pulses 42111.14 Advantages and disadvantages of coherence selection with gradients 42611.15 Suppression of zero-quantum coherence 42611.16 Selective excitation with the aid of gradients 43211.17 Further reading 43511.18 Exercises 43612 Equivalent spins and spin system analysis 44112.1 Strong coupling in a two-spin system 44212.2 Chemical and magnetic equivalence 44612.3 Product operators for AXn (InS) spin systems 45012.4 Spin echoes in InS spin systems 45512.5 INEPT in InS spin systems 45812.6 DEPT 46212.7 Spin system analysis 46812.8 Further reading 47712.9 Exercises 47813 How the spectrometer works 48313.1 The magnet 48313.2 The probe 48513.3 The transmitter 48613.4 The receiver 48813.5 Digitizing the signal 48913.6 Quadrature detection 49113.7 The pulse programmer 49313.8 Further reading 49313.9 Exercises 494A Some mathematical topics 495A.1 The exponential function and logarithms 495A.2 Complex numbers 497A.3 Trigonometric identities 499A.4 Further reading 500Index 501