Principles of Surface-Enhanced Raman Spectroscopy (eBook)

and Related Plasmonic Effects

Pablo Etchegoin, Eric Le Ru (Autoren)

eBook Download: EPUB

2008 | 1. Auflage
688 Seiten
Elsevier Science (Verlag)
978-0-08-093155-5 (ISBN)

Infos

Surface-Enhanced Raman Scattering (SERS) was discovered in the 1970s and has since grown enormously in breadth, depth, and understanding. One of the major characteristics of SERS is its interdisciplinary nature: it lies at the boundary between physics, chemistry, colloid science, plasmonics, nanotechnology, and biology. By their very nature, it is impossible to find a textbook that will summarize the principles needed for SERS of these rather dissimilar and disconnected topics. Although a basic understanding of these topics is necessary for research projects in SERS with all its many aspects and applications, they are seldom touched upon as a coherent unit during most undergraduate studies in physics or chemistry. This book intends to fill this existing gap in the literature. It provides an overview of the underlying principles of SERS, from the fundamental understanding of the effect to its potential applications. It is aimed primarily at newcomers to the field, graduate student, researcher or scientist, attracted by the many applications of SERS and plasmonics or its basic science. The emphasis is on concepts and background material for SERS, such as Raman spectroscopy, the physics of plasmons, or colloid science, all of them introduced within the context of SERS, and from where the more specialised literature can be followed.

* Represents one of very few books fully dedicated to the topic of surface-enhanced Raman spectroscopy (SERS)
* Gives a comprehensive summary of the underlying physical concepts around SERS
* Provides a detailed analysis of plasmons and plasmonics

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SERS was discovered in the 1970s and has since grown enormously in breadth, depth, and understanding. One of the major characteristics of SERS is its interdisciplinary nature: it lies at the boundary between physics, chemistry, colloid science, plasmonics, nanotechnology, and biology. By their very nature, it is impossible to find a textbook that will summarize the principles needed for SERS of these rather dissimilar and disconnected topics. Although a basic understanding of these topics is necessary for research projects in SERS with all its many aspects and applications, they are seldom touched upon as a coherent unit during most undergraduate studies in physics or chemistry. This book intends to fill this existing gap in the literature. It provides an overview of the underlying principles of SERS, from the fundamental understanding of the effect to its potential applications. It is aimed primarily at newcomers to the field, graduate students, researchers or scientists, attracted by the many applications of SERS and plasmonics or its basic science. The emphasis is on concepts and background material for SERS, such as Raman spectroscopy, the physics of plasmons, or colloid science, all of them introduced within the context of SERS, and from where the more specialized literature can be followed. - Represents one of very few books fully dedicated to the topic of surface-enhanced Raman spectroscopy (SERS)- Gives a comprehensive summary of the underlying physical concepts around SERS- Provides a detailed analysis of plasmons and plasmonics

Inhalt

Front cover 1
Half title 2
Title 4
Copyright page 5
Table of Contents 6
Preface 18
Notations, units and other conventions 22
Chapter 1. A quick overview of surface-enhanced Raman spectroscopy 26
What is SERS? -- Basic principles 26
SERS probes and SERS substrates 28
SERS substrates 28
SERS probes 31
Example 33
Other important aspects of SERS 34
SERS enhancements 34
Sample preparation and metal/probe interaction 35
Main characteristics of the SERS signals 36
Related techniques 38
Related areas 39
Applications of SERS 39
Raman with improved sensitivity 40
SERS vs fluorescence spectroscopy 40
Applications specific to SERS 42
The current status of SERS 42
Brief history of SERS 42
Where is SERS now? 45
Current `hot topics' 45
Overview of the book content 48
General outline of the book 48
General `spirit' of the book 49
Different reading plans 50
Chapter 2. Raman spectroscopy and related optical techniques 54
A brief introduction 55
The discovery of the Raman effect 55
Some applications of Raman spectroscopy 56
Raman spectroscopy instrumentation 57
Optical spectroscopy of molecules 58
The energy levels of molecules 58
Spectroscopic units and conversions 61
Optical absorption 63
Emission and luminescence 64
Scattering processes 67
The concept of cross-section 71
The Raman cross-sections 75
Examples of Raman cross-sections 78
Mechanical analogs 82
Absorption and fluorescence spectroscopy 84
Optical absorption and UV/Vis spectroscopy 84
Fluorescence spectroscopy 88
Photo-bleaching 92
Phenomenological approach to Raman scattering 95
Dipolar emission in vacuum 96
The concepts of polarizability and induced dipole 98
The linear optical polarizability 100
The Raman polarizability 102
The local field correction 102
Polarizabilities and scattering cross-sections 105
Final remarks on the phenomenological description 111
Vibrations and the Raman tensor 113
General considerations 113
A primer on vibrational analysis 114
The Raman tensor 116
Link to the Raman polarizability 117
Limitations of the classical approach 122
A brief overview of related Raman scattering processes 122
Quantum (or semi-classical) approach to Raman scattering 124
Justification of the classical approach 125
The quantization of vibrations 126
The full expressions for the Raman cross-section 127
The anti-Stokes to Stokes ratio 130
Advanced aspects of vibrations in molecules 131
More on vibrational analysis 131
More on symmetries and Raman selection rules 139
Modeling of molecular structure and vibrations 142
Summary 144
Chapter 3. Introduction to plasmons and plasmonics 146
Plasmonics and SERS 147
The optical properties of noble metals 147
The Drude model of the optical response 149
The optical properties of real metals 150
Non-local optical properties 152
What makes the metal--light interaction so special? 152
What are plasmons? 156
The plasmon confusion 156
Definition and history 157
The relation between plasmons and the dielectric function 160
Electromagnetic modes in infinite systems 161
Electromagnetic modes of a system of material bodies 166
Classification of electromagnetic modes 168
Other properties of electromagnetic modes 169
Summary and discussion 171
Surface plasmon--polaritons on planar interfaces 173
Electromagnetic modes for a planar dielectric/metal interface 174
Properties of the SPP modes at planar metal/dielectric interfaces 180
Coupling of PSPP modes with light 184
PSPP resonances at planar interfaces 189
Local field enhancements and SPPs at planar interfaces 192
SPP modes on planar interfaces: A brief summary 198
Localized surface plasmon--polaritons 199
Introduction to localized SPPs 199
LSP on planar structures 200
LSP modes of a metallic sphere 200
LSP modes of nano-particles 202
LSP resonances 202
Local field enhancements and LSP 203
Interaction of SPPs -- gap SPPs 204
Brief survey of plasmonics applications 206
Applications of surface plasmon resonances 206
SPP propagation and SPP optics 207
Local field enhancements 207
Chapter 4. SERS enhancement factors and related topics 210
Definition of the SERS enhancement factors 211
General considerations 212
The analytical point of view 215
The SERS substrate enhancement factor -- Experimental approach 216
The SERS cross-section and single-molecule EF 217
The SERS substrate enhancement factor -- Formal definition 222
Discussion and merits of the various definitions 223
Experimental measurement of SERS enhancement factors 225
The importance of the non-SERS cross-section 227
Example of AEF measurements 228
Link between SSEF definition and experiments 230
Overview of the main EM effects in SERS 234
Analysis of the EM problem of SERS 234
Local field enhancement 237
Radiation enhancement 239
Other EM effects 241
The common |E|4 -approximation to SERS enhancements 242
Modified spontaneous emission 244
Introduction 244
The link between spontaneous emission and dipolar emission 245
Modification of dipole emission: definitions of enhancement factors 249
Spontaneous emission and self-reaction 254
The Poynting vector approach 256
Spontaneous emission and the optical reciprocity theorem 258
Formal derivation of SERS EM enhancements 262
Definitions, notations, and assumptions 262
The SERS EM enhancement: general case 265
SERS EM enhancements in the back-scattering configuration 270
Surface-enhanced fluorescence (SEF) 273
Similarities and differences between SEF and SERS 273
Modified (enhanced) absorption 274
Modified fluorescence quantum yield 275
Fluorescence quenching and enhancement 276
Other EM effects in SERS 278
Fluorescence quenching in SERS 279
Photo-bleaching under SERS conditions 280
Non-radiative effects in SERS 282
The chemical enhancement 283
Introduction 283
The charge-transfer mechanism 284
Electromagnetic contribution to the chemical enhancement 286
The chemical vs electromagnetic enhancement debate 288
Summary 288
Chapter 5. Calculations of electromagnetic enhancements 290
Definition of the problem and approximations 291
The EM problem 291
Far field and local/near field 294
Some key EM indicators 298
The electrostatic approximation (ESA) 304
Other approximations 310
Analytical tools and solutions 311
Plane surfaces 312
The perfect sphere 312
Ellipsoids 314
Other approaches 314
Numerical tools 315
A brief overview of the EM numerical tools 315
A semi-analytical approach: the discrete dipole approximation 317
Direct numerical solutions 319
Other approaches 322
Chapter 6. EM enhancements and plasmon resonances: examples and discussion 324
Quenching and enhancement at planar surfaces 325
The image dipole approximation for the self-reaction field 325
Enhancement and quenching at plane metal surfaces 328
A simple example in detail: The metallic sphere 332
Metallic sphere in the ES approximation 333
Localized surface plasmon resonances and far-field properties 339
Local field effects 349
Distance dependence 360
Non-radiative effects -- surface-enhanced fluorescence 362
The effect of shape on the EM enhancements 367
Shape effects on localized surface plasmon resonances 368
Shape effects on local fields 371
Summary of shape effects 378
Gap effects -- junctions between particles 379
Coupled localized surface plasmon resonances and SERS 379
EF distribution and hot-spot localization 384
Additional effects 386
Nano-particles on a supporting substrate 387
Surface roughness 389
Factors affecting the EM enhancements: Summary 389
Chapter 7. Metallic colloids and other SERS substrates 392
Metallic colloids for SERS 393
Silver vs gold 393
Citrate-reduced colloids 394
Other types of colloids 396
Remarks on colloid fabrication methods 398
Dry colloids and other `2D planar' SERS substrates 398
Characterization of SERS substrates 400
Microscopy 400
Extinction or UV/Vis spectroscopy of SERS substrates 402
Other techniques: dynamic light scattering (DLS) for colloidal solutions 406
The stability of colloidal solutions 410
Introduction 410
The van der Waals interaction between metallic particles 411
The screened Coulomb potential 414
The DLVO interaction potential 419
Colloid aggregation within the DLVO theory 420
SERS with metallic colloids 424
Molecular (analyte) adsorption and SERS activity 424
Colloid aggregation for SERS 428
Focus on the `chloride activation' of SERS signals 431
SERS from `dried' colloidal solutions 432
SERS signal fluctuations 435
Chapter 8. Recent developments 440
Single-molecule SERS 440
Introduction 440
Early evidence for single-molecule detection 442
Langmuir--Blodgett monolayers 448
Bi-analyte techniques 450
Single-molecule SERS enhancement factors 458
Single-molecule SERS: Discussion and outlook 460
Tip-enhanced Raman spectroscopy (TERS) 461
Introduction to TERS 461
TERS with an atomic force microscope (AFM) 462
TERS with a scanning tunneling microscope (STM) 463
Theoretical calculations on tips 465
Discussion and outlook 467
New substrates from nano-technology 468
Chemical synthesis of metallic nano-particles 469
Self-organization 472
Nano-lithography 473
Adaptable/Tunable SERS substrates 476
Micro-fluidics and SERS 479
Optical forces 480
A simple theory of optical forces 480
Radiation pressure in colloidal fluids 482
Optical trapping of metallic particles 483
Optical forces on molecules 484
Applications of SERS 485
Analyte engineering and surface functionalization 485
Substrate reproducibility and SERS commercialization 487
Epilogue 488
Chapter A. Density functional theory (DFT) calculations for Raman spectroscopy 490
A brief introduction to DFT 490
Computing aspects of DFT 490
Principles of DFT 492
Important parameters 494
Applications of DFT to Raman 496
Principle 496
Geometry optimization using DFT 497
Limitations of DFT calculations for Raman 498
Practical implementation 499
Brief overview of the input and output files 499
Common units and definitions in Raman calculations from DFT 502
Normal mode patterns and Raman tensors 504
Examples of DFT calculations for SERS applications 510
Validation of absolute Raman cross-sections of reference compounds 510
Raman tensor and vibrational pattern visualizations 510
Depolarization ratio breakdown under SERS conditions 514
Chapter B. The bond-polarizability model 516
Principle and implementation 516
Principle 516
Calculation of bond polarizabilities 517
Practical implementation 520
A simple example in detail 521
Bond-polarizability analysis 521
Raman polarizabilities 522
A brief comment on the symmetry 523
Chapter C. A brief overview of Maxwell's equations in media 524
Maxwell's equations in vacuum 524
The equations 524
Maxwell's equations for harmonic fields in vacuum 526
Plane wave solutions in free-space 528
Maxwell's equations in media 528
Microscopic and macroscopic fields 528
The electromagnetic response of the medium 529
Electric polarization and magnetization 530
Constitutive relations 533
Boundary conditions between two media 537
Other aspects relevant to SERS and plasmonics 538
The microscopic field 538
Plane waves in media 540
Electromagnetic problems in SERS 542
Link with the static approach 543
Chapter D. Lorentz model of the atomic/molecular polarizability 548
The Lorentz oscillator 548
Principle 548
Multiple transitions (multiple resonances) 550
Example: linear optical polarizability of rhodamine 6G 550
Link with macroscopic properties 551
Dielectric function in a dilute medium 551
Dielectric function in solids 551
The metallic limit 552
Summary 553
Chapter E. Dielectric function of gold and silver 554
Model dielectric function for silver 554
Analytical expression 554
Comparison to experimental results 555
Model dielectric function of gold 556
Analytical expression 556
Comparison to experimental results 557
Remarks on the model dielectric functions 558
Limitations of the models 558
Comparison between Ag and Au 559
Chapter F. Plane waves and planar interfaces 562
The plane wave electromagnetic fields 562
General expressions 562
Propagating plane waves 564
Evanescent plane waves 564
Inhomogeneous plane waves: hybrid propagating/evanescent waves 565
Plane waves at a single planar interface 566
Plane wave polarization at an interface 566
General solution for plane waves at a planar interface 567
Physical waves in a semi-infinite region 571
The Fresnel coefficients 575
Surface modes 576
Incident wave modes 581
Reflection/Refraction at a planar interface 581
Incident, reflected, and transmitted waves 582
Snell's law 583
TM or p -polarized waves 583
TE or s -polarized waves 586
Special cases 588
Multi-layer interfaces 589
Principle 589
p -polarized or TM waves 590
s -polarized or TE waves 592
Particular cases of interest 592
Implementation in Matlab 592
Dipole emission close to a planar interface 595
Total decay rates 596
Radiative decay rates 596
Chapter G. Ellipsoids in the electrostatic approximation 598
General case 598
Some definitions 598
Ellipsoidal coordinates 599
The electrostatic solution 600
Some important EM indicators for ellipsoids 603
Some aspects of the numerical implementation 606
Oblate spheroid (pumpkin) 608
Geometrical factors 608
Surface averages 609
Limit of large aspect ratio 610
Prolate spheroid (rugby ball) 610
Geometrical factors 610
Surface averages 611
Limit of large aspect ratio 612
Chapter H. Mie theory and its implementation 614
Introduction 614
Motivation 614
Overview of this appendix 615
The concepts of Mie theory 615
The electromagnetic equations 615
The vectorial wave equation in spherical coordinates 616
Scattering by a sphere 618
Optical resonances of the sphere 621
Some aspects of the practical implementation of Mie theory 622
Basic formulas of Mie theory 623
Conventions 624
Spherical coordinates: A brief reminder 624
Definition and properties of the vector spherical harmonics 625
Expressions for the susceptibilities 630
More on optical resonances 632
Absorption, scattering, and extinction for an incident beam 633
Absorption and radiation for a localized source 636
Far-field radiation profile 637
The local field at the surface 637
Plane wave excitation of a sphere: The `original Mie theory' 638
Expansion of a plane wave in vector spherical harmonics 638
Extinction, scattering, and absorption for plane wave excitation 639
Average local field at the surface 640
Useful expansions for plane wave excitation 640
Extensions of Mie theory 640
Emitter close to a sphere 640
Coated spheres 646
Multiple spheres and generalized Mie theory (GMT) 650
Example of implementation of Mie theory with Matlab 651
Common problems 651
Other issues specific to Matlab 652
Some aspects of our implementation 652
References 654
Index 680

Produkt-Details

• Erscheint lt. Verlag: 17.11.2008
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Chemie ► Analytische Chemie
• Themenwelt: Naturwissenschaften ► Chemie ► Physikalische Chemie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie ► Angewandte Physik
• Themenwelt: Technik ► Maschinenbau
• ISBN-10: 0-08-093155-3 / 0080931553
• ISBN-13: 978-0-08-093155-5 / 9780080931555