Nanotechnology Understanding Small Systems

Rogers Pennathur Adams

0 ~~~,~~:~~p Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an lnforma business

Contents

Preface

Acknowledgments

Authors

CHAPTER 1 Big Picture and Principles of the Small World

1.2 UNDERSTANDING THE ATOM: EX NIH/LO NIHIL FIT

1.3 NANOTECHNOLOGY STARTS WITH A DARE: FEYNMAN'S BIG LITTLE

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CHALLENGES 10

1.4 WHY ONE-BILLIONTH OF A METER ISA BIG DEAL 14

1.5 THINKING IT THROUGH: THE BROAD IMPLICATIONS OF NANOTECHNOLOGY 17

1.5.1 Gray Goo

1.5.2 Environmental Impact

1.5.3 The Written Word

1.6 THE BUSINESS OF NANOTECH: PLENTY OF ROOM AT THE BOTTOM UNE TOO

1.6.1 Products

HOMEWORK EXERCISES

Short Answers

Writing Assignments

CHAPTER 2 lntroduction to Miniaturization

2.1 BACKGROUND: THE SMALLER, THE BETTER

2.2 SCALING LAWS

2.2.l The Elephant and the Flea

2.2.2 Scaling in Mechanics

2.2.3 Scaling in Electricity and Electromagnetism

2.2.4 Scaling in Optics

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2.2.5 Scaling in Heat Transfer

2.2.6 Scaling in Fluids

2.2.7 Scaling in Biology

2.3 ACCURACY OF THE SCALING LAWS

HOMEWORK EXERCISES

Short Answers

CHAPTER 3 lntroduction to Nanoscale Physics 3.1 BACKGROUND: NEWTON NEVER SAW A NANOTUBE

3.2 ONE HUNDRED HOURS AND EIGHT MINUTES OF NANOSCALE

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PHYSICS 53

3.3 THE BASICS OF QUANTUM MECHANICS 55

3.3.1 Atomic Orbitals (Not Orbits)

3.3.2 Electromagnetic Waves 3.3.2.1 How Electromagnetic Waves Are Made

3.3.3 The Quantization of Energy

3.3.4 Atomic Spectra and Discreteness

3.3.5 The Photoelectric Effect

3.3.6 Wave-Particle Duality: The Double-Slit Experiment 3.3.6.1 Bullets 3.3.6.2 Water Waves 3.3.6.3 Electrons

3.3.7 The Uncertainty Principle

3.3.8 Particle in a Well

3.4 SUMMARY

HOMEWORK EXERCISES

CHAPTER 4 Nanomaterials

4.1 BACKGROUND: MATTER MATTERS

4.2 BONDING ATOMS TO MAKE MOLECULES AND SOLIDS

4.2.l Ionic Bonding

4.2.2 Covalent Bonding

4.2.3 Metallic Bonding

4.2.4 Walking through Waals: van der Waals Forces 4.2.4.1 1he Dispersion Force

4.2.4.2 Repulsive Forces 4.2.4.3 1he van der Waals Force versus Gravity

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4.3 CRYSTAL STRUCTURES 97 4.4 STRUCTURES SMALL ENOUGH TO BE DIFFERENT (AND USEFUL) 99

4.4.1 Particles 99 4.4.1.1 Colloidal Particles 104

4.4.2 Wir es 104

4.4.3 Films, Layers, and Coatings 107

4.4.4 Porous Materials 108

4.4.5 Small-Grained Materials 110

4.4.6 Molecules 113 4.4.6.1 Carbon Fullerenes and Nanotubes 114 4.4.6.2 Dendrimers 118 4.4.6.3 Mice lies 120

4.5 SUMMARY 121

HOMEWORK EXERCISES 122

CHAPTER 5 Nanomechanics 127

5.1 BACKGROUND: THE UNIVERSE MECHANISM 127

5.1.1 Nanomechanics: Which Motions and Forces Make the Cut? 128

5.2 A HIGH-SPEED REVIEW OF MOTION: DISPLACEMENT, VELOCITY, ACCELERATION, AND FORCE 129

5.3 NANOMECHANICAL OSCILLATORS: A TALE OF BEAMS AND ATOMS 132

5.3.1 Beams 133 5.3.1.1 Free Oscillation 133 5.3.1.2 Free Oscillation from the Perspective of Energy

(and Probability) 136 5.3.1.3 Forced Oscillation 138

5.3.2 Atoms 144 5.3.2.1 The Lennard-Jones Interaction: How an Atomic Bond Is

Like a Spring 144 5.3.2.2 The Quantum Mechanics of Oscillating Atoms 149 5.3.2.3 The Schrödinger Equation and the Correspondence Principle 154 5.3.2.4 Phonons 159

5.3.3 Nanomechanical Oscillator Applications 162 5.3.3.1 Nanomechanical Memory Elements 163 5.3.3.2 Nanomechanical Mass Sensors: Detecting Low

Concentrations 165

5.4 FEELING FAINT FORCES 170

5.4.1 Scanning Probe Microscopes (SPMs) 170

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5.4.1.l Pushing Atoms around with the Scanning Tunneling Microscope (STM) 170

5.4.1.2 Skimming across Atoms with the Atomic Force Microscope (AFM) 171

5.4.1.3 Pulling Atoms Apart with the Atomic Force Microscope 176 5.4.1.4 Rubbing and Mashing Atoms with the Atomic Force

Microscope 178

5.4.2 Mechanical Chemistry: Detecting Molecules with Bending Beams 181

5.5 SUMMARY 185

HOMEWORK EXERCISES

CHAPTER 6 Nanoelectronics

6.1 BACKGROUND: THE PROBLEM (OPPORTUNITY)

6.2 ELECTRON ENERGY BANDS

6.3 ELECTRONS IN SOLIDS: CONDUCTORS, INSULATORS, AND SEMICONDUCTORS

6.4 FERMI ENERGY

6.5 THE DENSITY OF STATES FOR SOLIDS

6.5.1 Electron Density in a Conductor

6.6 TURN DOWN THE VOLUME! (HOW TO MAKE A SOLID ACT MORE LIKE AN ATOM)

6.7 QUANTUM CONFINEMENT

6.7.1 Quantum Structures 6.Zl.1 Uses for Quantum Structures

6.7.2 How Small Is Small Enough for Confinement? 6.Z2.l Conductors: 1he Metal-to-Insulator Transition 6.Z2.2 Semiconductors: Confining Excitons

6.7.3 The Band Gap ofNanomaterials

6.8 TUNNELING

6.9 SINGLE ELECTRON PHENOMENA

6.9.l Two Rules for Keeping the Quantum in Quantum Dot 6.9.1.l Rule 1: 1he Coulomb Blockade 6.9.1.2 Rule 2: Overcoming Uncertainty

6.9.2 The Single-Electron Transistor

6.10 MOLECULAR ELECTRONICS

6.10.l Molecular Switches and Memory Storage

6.11 SUMMARY

HOMEWORK EXERCISES

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fliAPTER 7 Nanoscale Heat Transfer

7.1 BACKGROUND: HOT TOPIC

7.2 ALL HEAT IS NANOSCALE HEAT

7.2.1 Boltzmann's Constant

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7.3 CONDUCTION 239

7.3.1 Tue Thermal Conductivity ofNanoscale Structures 241 7.3.1.1 Ihe Mean Free Path and Scattering of Heat Carriers 243 7.3.1.2 Ihermoelectrics: Better Energy Conversion with

Nanostructures 245 7.3.1.3 Ihe Quantum of1hermal Conduction 247

7.4 CONVECTION 249

7.5 RADIATION 250

7.5.1 Increased Radiation Heat Transfer: Mind the Gap! 250

7.6 SUMMARY 253

HOMEWORK EXERCISES 253

t:t-iAPTER 8 Nanophotonics 257

8.1 BACKGROUND: THE LYCURGUS CUP AND THE BIRTH OF THE PHOTON 257

8.2 PHOTONIC PROPERTIES OF NANOMATERIALS

8.2.l Photon Absorption

8.2.2 Photon Emission

8.2.3 Photon Scattering

8.2.4 Metals 8.2.4.1 Permittivity and the Free Electron Plasma 8.2.4.2 Ihe Extinction Coefficient of Meta[ Particles 8.2.4.3 Colors and Uses of Gold and Silver Particles

8.2.5 Semiconductors 8.2.5.l Tuning the Band Gap ofNanoscale Semiconductors 8.2.5.2 Ihe Colors and Uses ofQuantum Dots 8.2.5.3 Lasers Based on Quantum Confinement

8.3 NEAR-FIELD LIGHT

8.3.1 Tue Limits ofLight: Conventional Optics

8.3.2 Near-Field Optical Microscopes

8.4 OPTICAL TWEEZERS

8.5 PHOTONIC CRYSTALS: A BAND GAP FOR PHOTONS

8.6 SUMMARY

HOMEWORK EXERCISES

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CHAPTER 9 Nanoscale Fluid Mechanics

9.1 BACKGROUND: BECOMING FLUENT IN FLUIDS

9.1.l Treating a Fluid the Way lt Should Be Treated: Tue Concept of a Continuum 9.1.1.l Fluid Motion, Continuum Style: The Navier Stokes

Equations 9.1.1.2 Fluid Motion: Molecular Dynamics Style

9.2 FLUIDS AT THE NANOSCALE: MAJOR CONCEPTS

9.2.1 Swimming in Molasses: Life at Low Reynolds Numbers 9.2.1.1 Reynolds Number

9.2.2 Surface Charges and the Electrical Double Layer 9.2.2.1 Surface Charges at Interfaces 9.2.2.2 Gouy-Chapman-Stern Model and Electrical Double

Layer(EDL) 9.2.2.3 Electrokinetic Phenomenon

9.2.3 Small Particles in Small Flows: Molecular Diffusion

9.3 HOW FLUIDS FLOW AT THE NANOSCALE

9.3.1 Pressure-Driven Flow

9.3.2 Gravity-Driven Flow

9.3.3 Electroosmosis

9.3.4 Superposition of Flows

9.3.5 Ions and Macromolecules Moving through a Channel 9.3.5.1 Stokes Flow around a Particle 9.3.5.2 The Convection-Diffusion-Electromigration Equation:

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Nanochannel Electrophoresis 324 9.3.5.3 Macromolecules in a Nanojluidic Channel 327

9.4 APPLICATIONS OF NANOFLUIDICS 329

9.4.1 Analysis of Biomolecules: An End to Painful Doctor Visits? 330

9.4.2 ,EO Pumps: Cooling Off Computer Chips 331

9.4.3 Other Applications 331

9.5 SUMMARY 334

HOMEWORK EXERCISES 334

CHAPTER 10 Nanobiotechnology 337 10.1 BACKGROUND: OUR WORLD IN A CELL 337

10.2 INTRODUCTION: HOW BIOLOGY "FEELS" AT THE NANOMETER SCALE 339

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10.2.1 Biological Shapes at the Nanoscale: Carbon and Water Are the Essential Tools 339

10.2.2 Inertia and Gravity Are lnsignificant: Tue Swimming Bacterium 340

10.2.3 Random Thermal Motion 342

10.3 THE MACHINERY OF THE CELL 345

10.3.1 Sugars Are Used for Energy (But Also Structure) 345 10.3.1.1 Glucose 346

10.3.2 Fatty Acids Are Used for Structure (But Also Energy) 348 10.3.2.1 Phospholipids 350

10.3.3 Nucleotides Are Used to Store Information and Carry Chemical Energy 353 10.3.3.1 Deoxyribonucleic Acid (DNA) 355 10.3.3.2 Adenosine Triphosphate (ATP) 358

10.3.4 Amino Acids Are Used to Make Proteins 10.3.4.1 ATP Synthase

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10.4 APPLICATIONS OF NANOBIOTECHNOLOGY 364

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10.4.l Biomimetic Nanostructures

10.4.2 Molecular Motors

10.5 SUMMARY

HOMEWORK EXERCISES

Index 369