Understanding NMR Spectroscopy

Informationen zum Autor 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. Klappentext This text is aimed at people who have some familiarity with high-resolution NMR and who wish to deepen their understanding of how NMR experiments actually 'work'. This revised and updated edition takes the same approach as the highly-acclaimed first edition. The text concentrates on the description of commonly-used experiments and explains in detail the theory behind how such experiments work. The quantum mechanical tools needed to analyse pulse sequences are introduced set by step, but the approach is relatively informal with the emphasis on obtaining a good understanding of how the experiments actually work. The use of two-colour printing and a new larger format improves the readability of the text. In addition, a number of new topics have been introduced: How product operators can be extended to describe experiments in AX2 and AX3 spin systems, thus making it possible to discuss the important APT, INEPT and DEPT experiments often used in carbon-13 NMR. Spin system analysis i.e. how shifts and couplings can be extracted from strongly-coupled (second-order) spectra. How the presence of chemically equivalent spins leads to spectral features which are somewhat unusual and possibly misleading, even at high magnetic fields. A discussion of chemical exchange effects has been introduced in order to help with the explanation of transverse relaxation.* The double-quantum spectroscopy of a three-spin system is now considered in more detail.Reviews of the First Edition"For anyone wishing to know what really goes on in their NMR experiments, I would highly recommend this book" - Chemistry World"...I warmly recommend for budding NMR spectroscopists, or others who wish to deepen their understanding of elementary NMR theory or theoretical tools" - Magnetic Resonance in Chemistry Zusammenfassung This text discusses the high-resolution NMR of liquid samples and concentrates exclusively on spin-half nuclei (mainly 1 H and 13 C). It is aimed at people who are familiar with the use of routine NMR for structure determination and who wish to deepen their understanding of just exactly how NMR experiments work. Inhaltsverzeichnis Preface v Preface to the first edition vi 1 What this book is about and who should read it 1 1.1 How this book is organized 2 1.2 Scope and limitations 3 1.3 Context and further reading 3 1.4 On-line resources 4 1.5 Abbreviations and acronyms 4 2 Setting the scene 5 2.1 NMR frequencies and chemical shifts 5 2.2 Linewidths, lineshapes and integrals 9 2.3 Scalar coupling 10 2.4 The basic NMR experiment 13 2.5 Frequency, oscillations and rotations 15 2.6 Photons 20 2.7 Moving on 21 2.8 Further reading 21 2.9 Exercises 22 3 Energy levels and NMR spectra 23 3.1 The problem with the energy level approach 24 3.2 Introducing quantum mechanics 26 3.3 The spectrum from one spin 31 3.4 Writing the Hamiltonian in frequency units 34 3.5 The energy levels for two coupled spins 35 3.6 The spectrum from two coupled spins 38 3.7 Three spins 40 3.8 Summary 44 3.9 Further reading 44 3.10 Exercises 45 4 The vector model 47 4.1 The bulk magnetization 47 4.2 Larmor precession 50 4.3 Detection 51 4.4 Pulses 52 4.5 On-resonance pulses 57 4.6 Detection in the rotating frame ...

Autorentext

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.

Klappentext

This text is aimed at people who have some familiarity with high-resolution NMR and who wish to deepen their understanding of how NMR experiments actually 'work'. This revised and updated edition takes the same approach as the highly-acclaimed first edition. The text concentrates on the description of commonly-used experiments and explains in detail the theory behind how such experiments work. The quantum mechanical tools needed to analyse pulse sequences are introduced set by step, but the approach is relatively informal with the emphasis on obtaining a good understanding of how the experiments actually work. The use of two-colour printing and a new larger format improves the readability of the text. In addition, a number of new topics have been introduced: How product operators can be extended to describe experiments in AX2 and AX3 spin systems, thus making it possible to discuss the important APT, INEPT and DEPT experiments often used in carbon-13 NMR. Spin system analysis i.e. how shifts and couplings can be extracted from strongly-coupled (second-order) spectra. How the presence of chemically equivalent spins leads to spectral features which are somewhat unusual and possibly misleading, even at high magnetic fields. A discussion of chemical exchange effects has been introduced in order to help with the explanation of transverse relaxation. * The double-quantum spectroscopy of a three-spin system is now considered in more detail. Reviews of the First Edition "For anyone wishing to know what really goes on in their NMR experiments, I would highly recommend this book" - Chemistry World "...I warmly recommend for budding NMR spectroscopists, or others who wish to deepen their understanding of elementary NMR theory or theoretical tools" - Magnetic Resonance in Chemistry

Zusammenfassung
This text discusses the high-resolution NMR of liquid samples and concentrates exclusively on spin-half nuclei (mainly 1 H and 13 C). It is aimed at people who are familiar with the use of routine NMR for structure determination and who wish to deepen their understanding of just exactly how NMR experiments work.

Inhalt

Preface v

Preface to the first edition vi

1 What this book is about and who should read it 1

1.1 How this book is organized 2

1.2 Scope and limitations 3

1.3 Context and further reading 3

1.4 On-line resources 4

1.5 Abbreviations and acronyms 4

2 Setting the scene 5

2.1 NMR frequencies and chemical shifts 5

2.2 Linewidths, lineshapes and integrals 9

2.3 Scalar coupling 10

2.4 The basic NMR experiment 13

2.5 Frequency, oscillations and rotations 15

2.6 Photons 20

2.7 Moving on 21

2.8 Further reading 21

2.9 Exercises 22

3 Energy levels and NMR spectra 23

3.1 The problem with the energy level approach 24

3.2 Introducing quantum mechanics 26

3.3 The spectrum from one spin 31

3.4 Writing the Hamiltonian in frequency units 34

3.5 The energy levels for two coupled spins 35

3.6 The spectrum from two coupled spins 38

3.7 Three spins 40

3.8 Summary 44

3.9 Further reading 44

3.10 Exercises 45

4 The vector model 47

4.1 The bulk magnetization 47

4.2 Larmor precession 50

4.3 Detection 51

4.4 Pulses 52

4.5 On-resonance pulses 57

4.6 Detection in the rotating frame 60

4.7 The basic pulse-acquire experiment 60

4.8 Pulse calibration 61

4.9 The spin echo 63

4.10 Pulses of different phases 66

4.11 Off-resonance effects and soft pulses 67

4.12 Moving on 71

4.13 Further reading 71

4.14 Exercises 72

5 Fourier transformation and data processing 77

5.1 How the Fourier transform works 78

5.2 Representing the FID 82

5.3 Lineshapes and phase 83

5.4 Manipulating the FID and the spectrum 90

5.5 Zero filling 99

5.6 Truncation 100

5.7 Further …