Introduction to Nanotechnology

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Coventional TEM I Obj I Lens Scanning TEM b 3.3. MICROSCOPY 47 Figure 3.10. Ray diagram of a conventional transmission electron microscope (top path) and of a scanning transmission electron microscope (bottom path). The selected area electron diffraction (SAED) aperture (Ap) and the sample or specimen (Spec) are indicated, as well as the objective (Obj) and projector (Proj) or condenser (Cond) lenses. (Adapted from P. R. Buseck, J. M. Cowley, and L. Eyring, High-Resolution Transmission Electron Microscopy, Oxford Univ. Press, New York, 1988, p. 6.) an objective lens, are amplified by a magnifying (projector) lens, and finally produce the desired image, in the manner reading from left to right (CTEM direction) in Fig. 3.10. The wavelength of the electrons in the incident beam is given by a modified form of Eq. (3.6) 0.0388 A=- nm fl (3.7) where the energy acquired by the electrons is E = eV and V is the accelerating voltage expressed in kilovolts. If widely separated heavy atoms are present, they can dominate the scattering, with average scattering angles Q given by the expression 0 - A/d, where d is the average atomic diameter. For an accelerating voltage of 100 kV and an average atomic diameter of 0.15 nm, we obtain 0 - 0.026 radians or 1.5". Images are formed because different atoms interact with and absorb electrons to a different extent. When individual atoms of heavy elements are farther apart than several lattice parameters, they can sometimes be resolved by the TEM technique. Electrons interact much more strongly with matter than do X rays or neutrons with comparable energies or wavelengths. For ordinary elastic scattering of 100-keV electrons the average distance traversed by electrons between scattering events, called the mean freepath, varies from a few dozen nanometers for light elements to tens or perhaps hundreds of nanometers for heavy elements. The best results are obtained in electron microscopy by using film thicknesses that are comparable with
48 METHODS OF MEASURING PROPERTIES the mean free path. Much thinner films exhibit too little scattering to provide usehl images, and in thick films multiple scattering events dominate, making the image blurred and difficult to interpret. Thick specimens can be studied by detecting backscattered electrons. A transmission electron microscope can form images by the use of the selected- area electron diffraction (SAED) aperture located between the objective and projector lenses shown in Fig. 3.10. The main part of the electron beam transmitted by the sample consists of electrons that have not undergone any scattering. The beam also contains electrons that have lost energy through inelastic. scattering with no deviation of their paths, and electrons that have been reflected by various hkl crystallographic planes. To produce what is called a bright-jeld image, the aperture is inserted so that it allows only the main undeviated transmitted electron beam to pass, as shown in Fig. 3.1 1. The bright-field image is observed at the detector or viewing screen. If the aperture is positioned to select only one of the beams reflected from a particular hkl plane, the result is the generation of a dark-field image at the viewing screen. The details of the dark-field image that is formed can depend on the particular diffracted beam ( particular hkl plane) that is selected for the imaging. Figure 3.1 I shows the locations of the bright-field (BF) and dark-field (DF) aperture positions. To illustrate this imaging technique we present in Fig. 3.12 images of an iron base superalloy with a FCC austenite structure containing 2-3-nm y' preci- Fluorescent screen photographic film Primary @ ""1"" e:iFE.s detector Backscattered electron detector BF Bright-field (BF) and dark-field (DF) transmitted electron detectors Figure 3.11. Positioning of signal detectors in electron microscope column. (From D. B. Williams, Practical Analytical Electron Microscopy in Materials Science, Phillips Electronic Instruments, Mahwah NJ, 1984.)
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INTRODUCTION TO NANOTECHNOLOGY Char
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CONTENTS Preface xi 1 Introduction
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5.2 Carbon Molecules 103 5.2.1 Natu
Page 8 and 9: 9.4 Excitons 244 9.5 Single-Electro
Page 10 and 11: PREFACE In recent years nanotechnol
Page 12 and 13: INTRODUCTION The prefix nano in the
Page 14 and 15: INTRODUCTION 3 he recognized the ex
Page 16 and 17: 1000 (I) a 900 4 800 a 900 I 6 700
Page 18 and 19: INTRODUCTION 7 developed before the
Page 20 and 21: 2.1. STRUCTURE 9 mechanics, the res
Page 22 and 23: X T 2.1. STRUCTURE 11 Figure 2.4. C
Page 24 and 25: 2.1. STRUCTURE 13 Figure 2.6. Thirt
Page 26 and 27: Sodium Nanoparticle Na, Magic Numbe
Page 28 and 29: 2.1. STRUCTURE 17 of the large anio
Page 30 and 31: 2.1. STRUCTURE 19 other, and high-f
Page 32 and 33: 2.2. ENERGY BANDS 21 Conduction Ban
Page 34 and 35: 2.2. ENERGY BANDS 23 Figure 2.13. S
Page 36 and 37: 2.2. ENERGYBANDS 25 band at point T
Page 38 and 39: A X ' Wavevector A Si c z 2.2. ENER
Page 40 and 41: 2.2. ENERGY BANDS 29 bands of Figs.
Page 42 and 43: 2.3. LOCALIZED PARTICLES 31 add ele
Page 44 and 45: 1 meV 10 meV 100 meV FJ E W 1 eV 10
Page 46 and 47: 3 METHODS OF MEASURING PROPERTIES 3
Page 48 and 49: 3.2. STRUCTURE 37 Table 3.1. Crysta
Page 50 and 51: 3.2. STRUCTURE 39 Figure 3.2. Two-d
Page 52 and 53: 3.2. STRUCTURE 41 The widths of the
Page 55 and 56: 44 METHODS OF MEASURING PROPERTIES
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Page 62 and 63: 3.3. MICROSCOPY 51 types of transit
Page 64 and 65: 3.3. MICROSCOPY 53 Actual diverging
Page 66 and 67: Tunneling current Tunneling current
Page 68 and 69: 3.3. MrCAOSCOPY 57 and the latter m
Page 70 and 71: 3.4. SPECTROSCOPY 59 From Eq. (3.8)
Page 72 and 73: 1 Average Panicle FWHM Size (nm) in
Page 74 and 75: CdSe colloidal NCs a = 1.2 nrn 3.4.
Page 76 and 77: El X-RAY TUBE 8000 - A 6000 - 4000
Page 78 and 79: 2 N I w 3.0 2.5 2.0 1.5 1 .o 0.5 3.
Page 80 and 81: i 3.4. SPECTROSCOPY 69 NMR involves
Page 82 and 83: T=220K - 2G H FURTHER READING 71 Fi
Page 84 and 85: NUMBER OF ATOMS RADIUS (nm) 1 10 1
Page 86 and 87: I L 7 3 5 7 9 11 13 15 17 NUMBER OF
Page 88 and 89: JELLIUM MODEL OF CLUSTERS ATOMS CLU
Page 90 and 91: 1.02 { 1.01 - 1 - 0.99 - 4.2. METAL
Page 92 and 93: 4.2. METAL NANOCLUSTERS 81 Figure 4
Page 94 and 95: 4.2. METAL NANOCLUSTERS 83 Figure 4
Page 96 and 97: -0 100 200 300 400 500 600 MASSICHA
Page 98 and 99: a 42. METAL NANOCLUSTERS 87 Figure
Page 100 and 101: . . . .. . - . D 111111111111111111
Page 102 and 103: 3 4 2.5 0 cn g 2 0 z d 1.5 t a 9 1
Page 104 and 105: 4.3. SEMICONDUCTING NANOPARTICLES 9
Page 106 and 107: 4.4. RARE GAS AND MOLECULAR CLUSTER
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4.5. METHODS OF SYNTHESIS 97 d Figu
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4.5. METHODS OF SYNTHESIS 99 isopro
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PULSED LASER BEAM 1 1 1 1 1 I ROTAT
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5.1. INTRODUCTION CARBON NANOSTRUCT
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5.2. CARBON MOLECULES 105 methane d
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5.3. CARBON CLUSTERS 107 -0 20 40 6
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PHOTON ENERGY (electron volts) 5.3.
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Figure 5.6. Structure of the CEO fu
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1 30 0 14.1 14.2 14.3 14.4 14.5 LAT
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(c) 5.4. CARBON NANOTUBES 115 Figur
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5.4. CARBON NANOTUBES 1 17 The mech
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5.4. CARBON NANOTUBES 11 9 investig
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5.4. CARBON NANOTUBES 121 energy gr
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5.4. CARBON NANOTUBES 123 stretch c
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5.5. APPLICATIONS OF CARBON NANOTUB
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- v) 450 : 400 3 350 1 300 : 5 250
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BULK NANOSTRUCTURED MATERIALS In th
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h 8 0 6.1. SOLID DISORDERED NANOSTR
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6.1. SOLID DISORDERED NANOSTRUCTURE
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6.2. NANOSTRUCTURED CRYSTALS 153 qu
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6.2. NANOSTRUCTURED CRYSTALS 155 Fi
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158 BULK NANOSTRUCTURED MATERIALS 6
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160 BULK NANOSTRUCTURED MATERIALS w
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162 BULK NANOSTRUCTURED MATERIALS 0
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164 BULK NANOSTRUCTURED MATERIALS n
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166 NANOSTRUCTURED FERROMAGNETISM f
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168 NANOSTRUCTURED FERROMAGNETISM i
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170 NANOSTRUCTURED FERROMAGNETISM M
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172 NANOSTRUCTURED FERROMAGNETISM h
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174 NANOSTRUCTURED FERROMAGNETISM d
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176 NANOSTRUCTURED FERROMAGNETISM o
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4 h $ 3 7.5. NANOCARBON FERROMAGNET
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7.6. GIANT AND COLOSSAL MAGNETORESI
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1.4 N 1 1.2 z " 1 0 v 5 h 0.8 0 0.6
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7.6. GIANT AND COLOSSAL MAGNETORESI
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7.7. FERROFLUIDS 187 Figure 7.22. M
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7.7. FECIROFLUIDS 189 Figure 7.25.
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7.7. FERRQFLUlOS 191 FerroRuids can
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FURTHER READING FURTHER READING 193
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10- IR f IA -1 8.1. INTRODUCTION 19
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8.2. INFRARED FREQUENCY RANGE 197 1
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8.2. INFRARED FREQUENCY RANGE 199 d
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s C CTI e 8 9 4( 8.2. INFRARED FREQ
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8.2.3. Raman Spectroscopy 8.2. INFR
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8.2. INFRARED FREQUENCY RANGE 205 a
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- r I 520 51 8 v 6 516 a" 51 4 51 2
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8.2. INFRARED FREQUENCY RANGE 209 i
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v) - C 3 8 600 400 100 0 e e 10 20
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i E (cm-’ ) 20 c I 1 ID 0 4x107 8
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- ? m v .- - z In C a, c C - .. . .
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Excitatior I [eV]: 2.175 2.214 2.25
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6 100 200 300 Time (ns) 8.3. LUMINE
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400 nm Laser / Free excitons Trappe
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8.4. NANOSTRUCTURES IN ZEOLITE CAGE
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FURTHER READING 225 P. Milani and C
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9.2. PREPARATION OF QUANTUM NANOSTR
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i 9.2. PREPARATION OF QUANTUM NANOS
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9.3. SIZE AND DIMENSIONALITY EFFECT
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w n 3 2 1 9.3. SIZE AND DIMENSIONAL
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WE) Quantum Dot Number of Electrons
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9.5. SINGLE-ELECTRON TUNNELING 245
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9.5. SINGLE-ELECTRON TUNNELING 247
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1 pair section ;- COT. .; . . I. .
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o.6 LWIR: T = 77 K 45" incidence AD
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9.7. SUPERCONDUCTIVITY 253 horizont
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9.7. SUPERCONDUCTIVITY 255 applied
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10.1. SELF-ASSEMBLY 10 SELF-ASSEMBL
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10.1. SELF-ASSEMBLY 259 factor of 2
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(a) (LI (dl 10.1. SELF-ASSEMBLY 261
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10.1. SELF-ASSEMBLY 263 atoms, as n
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- c v) ._ C 3 2 9 40 c - .- e m v w
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10.2. CATALYSIS 267 where the lengt
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10.2. CATALYSIS 269 are also other
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1600 2 1200 t p - Bi2M020, 10.2. CA
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7 - I 2,330 m .- c r 0 2 2,300 - u)
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10.2. CATALYSIS 275 with a top and
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10.2. CATALYSIS 277 based on the pr
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10.2. CATALYSIS 279 CnHlnfl, which
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I1 ORGANIC COMPOUNDS AND POLYMERS 1
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11.2. FORMING AND CHARACTERIZING PO
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1 1.3. NANOCRYSTALS 285 This expres
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-1 5 0) C a, -1 1 000 300 100 30 10
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11.3. NANOCRYSTALS 289 Table 11.1.
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11.3. NANOCRYSTALS 291 R’ groups
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11.4. POLYMERS 293 Figure 11.9. Ske
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11.5. SUPRAMOLECULAR STRUCTURES 295
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M Et3P OTf M=Pd M=Pt M=Pd, 41 % M=P
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11.5. SVPRAMOLECUUAR STRUCTURES 2s
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11 5. SUPRAMOLECULAR STRUCTURES 303
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BiodegradaWe surface 4 Functional g
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FURTHER READING 309 F. J. Owens and
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12.2. BIOLOGICAL BUILDING BLOCKS 31
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314 BIOLOGICAL MATERIALS which we w
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316 BIOLOGICAL MATERIALS Table 12.2
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318 BIOLOGICAL MATERtALS i J / Flgu
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320 BIOLOGICAL MATERIALS Pyrimidine
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322 BlOLMjlCAL MATERiALS (a) DNA do
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324 BIOLOGICAL MATERIALS so each wo
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326 BIOLOGICAL MATERIALS 12.4.2. Mi
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328 BIOLOGICAL MATERIALS tions they
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330 BIOLOGICAL MATERIALS hardened f
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13 NANOMACHINES AND NANODEVICES In
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334 NANOMACHINES AND NANODEVICES CA
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336 NANOMACHINES AND NANODEVICES Op
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338 NANOMACHINES AND NANODEVICES ti
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340 NANOMACHINES AN0 NANODEVICES PO
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342 NANOMACHINES AND NANODEVICES X
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344 NANOMACHINES AND NANODEVICES na
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346 NANOMACHINES AND NANODEVICES 31
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348 NANOMACHINES AND NANODEVICES -
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350 NANOMACHINES AND NANODEVICES re
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352 NANOMACHINES AND NANODEVICES 1
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354 NANOMACHINES AND NANODEVICES -1
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A.l. INTRODUCTION APPENDIX A FORMUL
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A.3. PARTIAL CONFINEMENT 359 limiti
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APPENDIX B TABULATIONS OF SEMICONDU
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TABULATIONS OF SEMICONDUCTING MATER
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Table B.8. Effective masses m+ rela
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372 INDEX amoeba, 3 16 amphiphilic,
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374 INDEX CdS, 9, 130, 213, 216, 36
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376 INDEX dispersion, 277 disulfide
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378 INDEX Ga (gallium) (continued)
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380 INDEX length (continued) critic
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382 INDEX multiple ionization, 93 r
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384 INDEX pi-conjugation, 282, 292
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silica, 269 silica-alumina, 269, 27
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388 INDEX wavefimction (continued)
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Introduction to Nanotechnology

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