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Diffusion NMR of Confined Systems

Diffusion NMR of Confined Systems

Rustem Valiullin

(2016)

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Book Details

Abstract

With the increasing role of porous solids in conventional and newly emerging technologies, there is an urgent need for a deeper understanding of fluid behaviour confined to pore spaces of these materials especially with regard to their transport properties. From its early years, NMR has been recognized as a powerful experimental technique enabling direct access to this information. In the last two decades, the methodological development of different NMR techniques to assess dynamic properties of adsorbed ensembles has been progressed. This book will report on these recent advances and look at new broader applications in engineering and medicine.
Having both academic and industrial relevance, this unique reference will be for specialists working in the research areas and for advanced graduate and postgraduate studies who want information on the versatility of diffusion NMR.

Table of Contents

Section Title Page Action Price
Cover Cover
Contents vii
Preface v
Chapter 1 NMR under Confinement: Roots in Retrospect 1
References 12
Chapter 2 Fundamentals of Diffusion Measurements using NMR 16
2.1 What is Diffusion? 16
2.1.1 Self-diffusion, Mutual Diffusion, Flow and Dispersion 16
2.1.2 Free and Restricted Diffusion 18
2.1.3 Diffusion in General Porous Media 28
2.2 How to Measure Diffusion using Magnetic Resonance 30
2.2.1 Radiofrequency Pulses and Gradients 30
2.2.2 Pulsed Gradient Diffusion Sequences 32
2.2.3 The Torrey-Bloch Equations and Application to the PGSE Sequence 33
2.2.4 Anisotropic Systems with Uniform Orientation 35
2.2.5 Anisotropic Systems with Powder Distributions 38
2.3 Experimental Measurements 40
2.3.1 An ‘Ideal PGSE' Experiment and Analysis 40
2.3.2 Optimising PGSE Experiments 41
2.3.3 Real Experiments, Complications and Solutions 44
References 46
Chapter 3 From the Microstructure to Diffusion NMR, and Back 52
3.1 Introduction 52
3.2 Mathematical Background 53
3.2.1 Bloch-Torrey Equation 53
3.3 Boundary Conditions 55
3.4 Diffusion-weighting Magnetic Field 58
3.5 Characteristic Scales 62
3.6 Solutions of the Bloch-Torrey Equation 64
3.7 Theoretical Approaches 66
3.7.1 Narrow-pulse Approximation 66
3.7.2 Gaussian Phase Approximation 70
3.8 Diffusion in Multi-compartmental Tissue 79
3.8.1 Multi-exponential and Distributed Signals 80
3.8.2 Bi-exponential Model 81
3.8.3 Kärger Model\r 84
3.8.4 Anomalous Diffusion Models 86
3.8.5 Effective Medium Theory 87
3.9 Towards Microscopic Geometric Models 88
3.10 Towards High Gradients 89
3.11 Conclusions and Perspectives 94
References 96
Chapter 4 Two-dimensional NMR of Diffusion and Relaxation 111
4.1 Introduction 111
4.2 Basic Pulse Sequence Building Blocks and Experiments 112
4.2.1 Relaxation Correlation Experiments 114
4.2.2 Diffusion-Relaxation Correlation Experiments 115
4.2.3 Correlation Experiments in Static Field Gradients 116
4.2.4 Correlation Experiments in RF Field Gradients 116
4.2.5 Mixed Diffusion and Relaxation Experiment 117
4.2.6 Diffusion Time Correlation Experiment 117
4.2.7 Diffusion Anisotropy Correlation 120
4.2.8 DDIF-CPMG 120
4.2.9 Fast Acquisition of 2D NMR 121
4.2.10 Summary 122
4.3 Diffusion Dynamics in Porous Media 122
4.3.1 Theory 122
4.3.2 NMR Experiments 123
4.4 Laplace Inversion 125
4.4.1 General Theory 126
4.4.2 Data Compression 126
4.4.3 Mellin Transform 128
4.4.4 Max Entropy Method 130
4.4.5 Monte Carlo Inversion 133
4.4.6 Time-domain Analysis 135
4.4.7 Summary 136
4.5 Applications 136
4.5.1 Well-logging 136
4.5.2 Water Saturation 136
4.5.3 Drilling Fluid Invasion 138
4.5.4 Oil Composition Measurement 139
4.5.5 Surface Relaxivity 139
4.5.6 Diffusion Correlation 141
4.5.7 Pore Structure 141
4.5.8 Nanoporous Shales 143
4.5.9 Biological Materials 145
4.5.10 Food Materials 146
4.5.11 Cement and Other Materials 146
4.5.12 Environmental Sciences 147
4.6 Instrumentation 147
4.7 Summary 148
References 148
Chapter 5 Transport in Structured Media: Multidimensional PFG-NMR Applied to Diffusion and Flow Processes 156
5.1 Introduction: Diffusion vs. Transport 156
5.2 Theoretical Background 158
5.2.1 Encoding of Transport Properties 158
5.2.2 Two- and Higher-dimensional Sequences 161
5.3 Examples for Flow and Correlations in Displacements 164
5.3.1 Velocity EXchange SpectroscopY (VEXSY) 164
5.3.2 Diffusion EXchange SpectroscopY (DEXSY) 167
5.3.3 Two- and Three-dimensional Propagators 170
5.3.4 Local Anisotropy of Diffusion 179
5.4 Velocity Encoding and Imaging: Recent Developments 181
5.5 Summary 190
References 190
Chapter 6 Real Time PGSE NMR Through Direct Acquisition of Averaged Propagators in the Time Domain Using Pulsed Second Order Magnetic Fields 194
6.1 Introduction 194
6.1.1 General Background 194
6.1.2 PGSE NMR for Diffusion and Flow 196
6.2 Time Domain Signal as the Averaged Propagator 197
6.2.1 The Conventional PGSE Experiment 197
6.2.2 The PGSE Experiment using Second Order Magnetic Fields 199
6.3 Applications 208
6.3.1 Real Time Propagator Measurements 208
6.3.2 Single-shot Surface-to-volume Ratios for Porous Materials 215
6.4 Conclusions 220
References 221
Chapter 7 NMR Methods for Studying Microscopic Diffusion Anisotropy 226
7.1 Introduction 226
7.2 Tensors 228
7.2.1 Tensor Size and Shape 229
7.2.2 Tensors with Axial Symmetry 231
7.2.3 Alternative Measures of Tensor Anisotropy 232
7.3 Ensembles of Diffusion Tensors 233
7.3.1 Diffusion Tensor Distributions 233
7.3.2 Size and Shape Distributions 234
7.3.3 Means and Variances 234
7.3.4 Orientation Distributions and Order Tensors 235
7.3.5 Ensemble-averaged Diffusion Tensor 237
7.4 NMR Methods and Application Examples 238
7.4.1 Diffusion Encoding with Magnetic Field Gradients 238
7.4.2 Method Classification Based on the Shape of the b-Tensor 239
7.4.3 General Principles for Designing Measurement Protocols 242
7.4.4 Signal from Powders 242
7.4.5 Powder-averaging of the Signal 245
7.4.6 Detecting Microscopic Diffusion Anisotropy 246
7.4.7 Cumulant Expansion of the Signal 247
7.4.8 Variance of Isotropic Diffusivities and Mean-square Anisotropy from the 2nd Moment 248
7.4.9 Model-free Estimation of the 2nd Moment 249
7.4.10 Mapping the Variance of Isotropic Diffusivities and Mean-square Anisotropy 250
7.4.11 Mapping Microscopic Diffusion Tensors and Orientational Order Tensors 251
7.4.12 Microscopic Anisotropy Parameters for Clinical MRI 251
7.4.13 Removing the Need for Powder Averaging: The Covariance Tensor 253
7.4.14 2D Size-shape Diffusion Tensor Distribution 253
7.5 Conclusions 255
Acknowledgments 255
References 255
Chapter 8 Beyond the Limits of Conventional Pulsed Gradient Spin Echo (PGSE) Diffusometry: Generalization of the Magnetization-grating Principle 260
8.1 Introduction 260
8.2 Diffusometry using the B0 Gradients of the Fringe Field of Magnets 262
8.2.1 Formalism for the Fringe-field SGSE Technique 264
8.2.2 Determination of the Size of Polymeric Capsules with the Aid of the Fringe-field SGSE Technique 269
8.3 Diffusometry using B1 Gradients 271
8.3.1 Stimulated Rotary Spin Echo 271
8.3.2 Nutation Spin Echo 275
8.3.3 MAGROFI 277
8.3.4 Applications of Rotating-frame Techniques for Diffusion Studies 280
8.4 Laboratory-frame Diffusometry Based on Non-linear (or ‘‘multiple\") Stimulated Echoes 283
8.4.1 The Demagnetizing Field 284
8.4.2 Formation of Non-linear Stimulated Echoes and Evaluation of Diffusion Coefficients 285
8.5 Conclusions 289
Acknowledgments 291
References 292
Chapter 9 Probing Exchange and Diffusion in Confined Systems by 129Xe NMR Spectroscopy 294
9.1 Introduction to the Use of 129Xe NMR to Investigate the Structure and Transport Phenomena in Confined Systems 294
9.2 Theoretical Background and Hardware 296
9.2.1 Factors Influencing the Chemical Shift of 129Xe 296
9.2.2 The Spin Exchange Optical Pumping Method 299
9.2.3 Hardware Aspects 301
9.3 NMR Experiments and their Application 305
9.3.1 EXSY-experiments 306
9.3.2 The Hyperpolarized Tracer Exchange Experiment 311
9.3.3 The HyperCEST Approach 313
9.4 Summary 314
References 314
Chapter 10 Diffusive Dynamics in Porous Materials as Probed by NMR Relaxation-based Techniques 318
10.1 Introduction 318
10.2 Limiting Nuclear Magnetic Relaxation Processes of a Liquid in Pores 320
10.3 Nuclear Magnetic Relaxation Dispersion of Longitudinal Relaxation Rate in Calibrated Micropores 323
10.3.1 Theory 323
10.3.2 Application to Aprotic Liquids 327
10.3.3 Application to Protic (Water) Liquid 328
10.4 Continuous Multi-scales NMR Relaxation Investigation of Microstructure Evolution of Cement-based Materials 330
10.5 Direct Probing of the Nano-wettability of Plaster Pastes 335
10.6 Dynamical Surface Affinity of Diphasic Liquids as a Probe of Wettability of Multimodal Macroporous Petroleum Rocks 341
10.7 Dynamics and Wettability of Oil and Water in the Dual Organic and Mineral Porosity of Shales Oils 345
10.7.1 Samples 345
10.7.2 Methods 345
10.7.3 Interpretation of the Nuclear Magnetic Relaxation Dispersion Data 347
10.8 Conclusion 350
Acknowledgments 350
References 350
Chapter 11 Industrial Applications of Magnetic Resonance Diffusion and Relaxation Time Measurements 353
11.1 Introduction 353
11.2 NMR Petrophysics 355
11.2.1 Magnetic Resonance Well Logging 355
11.2.2 Laboratory Core Analysis 357
11.2.3 Relaxation Time Distributions 358
11.2.4 Diffusion as a Contrast Mechanism 359
11.2.5 Internal Gradients 362
11.3 Rock Lithology 364
11.3.1 Sandstone 364
11.3.2 Carbonates 366
11.3.3 Unconventionals 368
11.4 Advanced NMR Petrophysics 371
11.4.1 Wettability 371
11.4.2 Capillary Pressure 373
11.4.3 Hydrodynamics 374
11.4.4 Oil Recovery 377
11.5 Applications in Other Industries 381
11.6 Summary 383
Acknowledgments 384
References 384
Chapter 12 Confined Fluids: NMR Perspectives on Confinements and on Fluid Dynamics 390
12.1 Introduction 390
12.2 Basic Properties of Confined Fluids 391
12.2.1 Phase State 391
12.2.2 Diffusion Mechanisms 393
12.2.3 Trajectory Analysis for Multi-phase Systems 395
12.2.4 Restricted Diffusion 398
12.2.5 Potentials of NMR for Delivering Complementary Information 399
12.3 Structural Information Accessible by Diffusion NMR 401
12.3.1 Tortuosity of the Pore Space 401
12.3.2 Surface-to-volume Ratio 404
12.3.3 Pore Size in Closed and Interconnected Pore Systems 408
12.3.4 Pore Space Anisotropy 412
12.3.5 Hierarchical Pore Spaces 413
12.3.6 Pore Space Organization 418
12.4 Fluid Behavior in Confined Spaces 419
12.4.1 Surface Diffusion 419
12.4.2 Global Equilibration Dynamics 422
12.4.3 Memory Effects in Confined Fluids 424
12.4.4 Ergodicity Theorem for Diffusion 426
12.5 Conclusions and Perspectives 428
References 428
Chapter 13 NMR and Complementary Approaches to Establishing Structure-Transport Relationships in Disordered Porous Solids 435
13.1 Introduction 435
13.2 Surface Diffusion 437
13.2.1 NMR Studies of Surface Diffusion 437
13.2.2 Structure-Transport Model for Surface Diffusion Validated by NMR 438
13.3 Pore Diffusion 448
13.4 Structural Characterization and its Validation 448
13.4.1 Gas Sorption 448
13.4.2 Pore-Pore Co-operation Effects 451
13.4.3 Cryoporometry 452
13.4.4 Application of NMR Diffusometry to Improving Structural Characterization 452
13.5 Conclusion 462
References 462
Chapter 14 NMR Diffusometry for the Study of Energy-related Soft Materials 464
14.1 Introduction to Energy-related Soft Materials 464
14.1.1 Soft Materials: Polymers, Ionic Liquids, Plastic Crystals, Liquid Crystals, Gels 465
14.1.2 Morphology vs. Molecular Features that Influence Transport 468
14.2 How Can NMR Diffusometry Help Us Understand Soft Materials? 469
14.2.1 Overview: Chemical Selectivity and Tunable Translational Time/Length Scale 469
14.2.2 Signal Analysis: SGP and GPD Approximations 471
14.2.3 Restricted Diffusion in Polymer Membranes 473
14.2.4 Activation Energy: A Window into Molecular Motion on ~1 nm Scales\r 474
14.3 Key Challenges and Experimental Aspects in Nanostructured Soft Materials 476
14.3.1 Lower Length-scale Limit, Short T2, and Signal Loss 476
14.3.2 Artifacts When Using High Gradients to Observe Slow Diffusing Species 477
14.3.3 Pre-averaging over Small Length Scale Heterogeneity 480
14.3.4 Fruitful Combinations of NMR Techniques: Multimodal NMR 481
14.4 Key Applications in Energy-related Soft Materials 482
14.4.1 Nanostructured Ionic Polymer Membranes: Nanochannel Alignment and Diffusion Anisotropy 482
14.4.2 Ionic Liquids Inside Nanostructured Polymers: Ion Associations 486
14.4.3 Organic Ionic Plastic Crystals 488
14.4.4 Ion Motions in Polymer-gel Battery Electrolytes 490
14.5 Conclusion and Outlook 493
Acknowledgments 494
References 494
Chapter 15 Diffusion Magnetic Resonance Imaging in Brain Tissue 497
15.1 Introduction 497
15.1.1 Diffusion Basics 498
15.1.2 How are dMRI Experiments Performed? 500
15.2 Water Diffusion in Brain Tissue 503
15.2.1 Complex Brain Microstructure and the Apparent Diffusion Coefficient 503
15.2.2 Diffusion Tensor Imaging 507
15.2.3 Non-Gaussian Diffusion 510
15.3 Selected Applications of dMRI 513
15.3.1 Diffusion Contrast in Ischemic Stroke 513
15.3.2 Diffusion Changes in Development and Aging 515
15.3.3 Fibre Tractography and Human Connectomics 517
15.4 Conclusions 519
References 520
Chapter 16 Surface Effect Dominates Water Diffusion at Nanoscopic Length Scales 529
16.1 Introduction 529
16.2 1H ODNP Theory and Analysis of Local Water Diffusivity 535
16.2.1 Moving from ξ to Dbulk/Dlocal\r 535
16.2.2 Experimentally Determining ξ\r 537
16.3 Results: ODNP Case Studies 538
16.3.1 Translational Diffusivity of LUV Surface Water and Its Activation Energy 538
16.3.2 Decoupling of Surface Water Dynamics on LUV from Bulk Solvent Viscosity 542
16.3.3 LUV Bilayer-internal Water Diffusion and Its Activation Energy 546
16.3.4 Lipid Membrane Integrity Relies on Stable Hydration Shell 551
16.3.5 Effect of Confinement in a Biological GroEL/GroES Chaperone on Water 554
16.3.6 Heterogeneous Water Dynamics within Nafion® Inner Membranes 556
16.4 Conclusion 563
Acknowledgments 563
References 563
Subject Index 568