Physical Principles of Electron Microscopy: An Introduction to TEM ...

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178 Chapter 7 Figure 7-1. Modified VG HB-501 STEM fitted with a gun monochromator, 120-kV Nion spherical-aberration corrector, ADF detector, and aberration-corrected electron spectrometer. Courtesy of Phil Batson, IBM Watson Research Laboratory, and Ondrej Krivanek, Nion Co.
Recent Developments 179 Figure 7-2. (a) ADF-STEM image of a catalyst specimen, showing individual Pt atoms on the surface of an alumina support; the circles indicate Pt3 trimers. Courtesy of R.D. Adams and M. Amiridis, University of South Carolina, A. Borisevich and S. Pennycook, Oak Ridge National Laboratory. (b) Image of a silicon crystal recorded with the electron beam parallel to (112), showing pairs of atomic columns 0.078 nm apart. Courtesy of Matthew F. Chisholm, ORNL, reprinted with permission from Science 305 (2004) 1741; copyright 2004 AAAS. Both of these images were recorded using the aberration-corrected VG603 STEM at ORNL. Because the dedicated STEM has a field-emission source and a strongly excited objective lens (low Cs), it can form a probe of diameter � 0.2 nm, offering the possibility of single-atom resolution. One area of application has been the study of the structure of catalysts, which typically consist of very small metal particles on an oxide support; see Fig. 7-2a. The STEM can also produce atomic-resolution images of crystalline specimens. If the specimen is oriented with a low-index crystal axis parallel to the incident beam, columns of atoms can be resolved (Fig. 7-2b), as in the case of phase-contrast TEM images. However, the ADF detector provides an amplitude (scattering-contrast) signal that is relatively insensitive to the objective-lens focus; there are no contrast reversals (Section 4.9) and the image is more directly interpretable in terms of atomic coordinates. As shown in Fig. 7-1, the STEM is usually fitted with an energy-loss spectrometer that forms a spectrum from electrons (with scattering angle up to �min) that pass through a central hole in the ADF detector. This arrangement allows dark-field and energy-filtered bright-field images to be recorded simultaneously. Also, after recording an atomic-resolution ADF image, the electron probe can be set to a precisely known location on the specimen and the electron spectrometer used to provide elemental or finestructure analysis with a spatial resolution down to the atomic level (Browning et al., 1997).
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Physical Principles of Electron Mic
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Ray F. Egerton Department of Physic
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Contents Preface xi 1. An Introduct
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Contents ix 7. Recent Developments
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xii Preface textbooks, such as Will
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2 1.1 Limitations of the Human Eye
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4 Chapter 1 parallel beam of light
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6 Chapter 1 Figure 1-3. One of the
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8 Chapter 1 Figure 1-5. Light-micro
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10 Chapter 1 Figure 1-7. Scanning t
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12 Chapter 1 Figure 1-8. Early phot
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14 Chapter 1 Figure 1-10. JEOL tran
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16 Chapter 1 hydrated. But high-ene
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18 Chapter 1 Figure 1-14. Scanning
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20 Chapter 1 Figure 1-16. Photograp
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22 Chapter 1 visible-light photons
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24 Chapter 1 Typically, the STM hea
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Chapter 2 ELECTRON OPTICS Chapter 1
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Electron Optics 29 a c b object len
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Electron Optics 31 � a n 2 ~1.5
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Electron Optics 33 We can define im
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Electron Optics 35 electron source
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Electron Optics 37 symmetry and use
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Electron Optics 39 As we said earli
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Electron Optics 41 2.4 Focusing Pro
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Electron Optics 43 � = [e/(8mE0)
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Electron Optics 45 image plane. Whe
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Electron Optics 47 procedure that i
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Electron Optics 49 The basic physic
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Electron Optics 51 From Eq. (2.7),
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Electron Optics 53 y +V 1 +V 2 -V 2
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Electron Optics 55 point from the o
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58 Chapter 3 3.1 The Electron Gun T
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60 Chapter 3 The rate of electron e
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62 Chapter 3 electron emission curr
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64 Chapter 3 As seen from the right
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66 Chapter 3 � r r s r � (a) (b
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68 Chapter 3 Table 3-2. Speed v and
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70 Chapter 3 where G is a large amp
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72 Chapter 3 The second condenser (
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74 Chapter 3 Figure 3-9 summarizes
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76 Chapter 3 resolution (especially
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78 Chapter 3 The major advantage of
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80 Chapter 3 contrast (for a given
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82 Chapter 3 A more correct procedu
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84 Chapter 3 diffraction pattern (s
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86 Chapter 3 Nowadays, photographic
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88 Chapter 3 A related concept is d
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90 Chapter 3 molecules, imparting a
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92 Chapter 3 Frequently, liquid nit
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94 Chapter 4 -e -e -e -e +Ze Figure
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96 Chapter 4 � (a) elastic z x m
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98 Chapter 4 � b a (a) (b) Figure
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100 Chapter 4 fraction of electrons
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102 Chapter 4 whose composition or
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104 Chapter 4 replica crystallites
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106 Chapter 4 4.5 Diffraction Contr
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108 Chapter 4 remain undiffracted (
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110 Chapter 4 Close examination of
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112 Chapter 4 Unfortunately, the va
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114 Chapter 4 Crystals can also con
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116 Chapter 4 A simple example of p
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118 Chapter 4 High-magnification ph
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120 Chapter 4 At this stage it is c
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122 Chapter 4 All of the above meth
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124 Chapter 4 The procedures outlin
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Page 136 and 137: 128 Chapter 5 functions with m and
Page 138 and 139: 130 Chapter 5 inelastic collisions
Page 140 and 141: 132 Chapter 5 Figure 5-5. Dependenc
Page 142 and 143: 134 Chapter 5 Figure 5-7. (a) Secon
Page 144 and 145: 136 Chapter 5 Because each secondar
Page 146 and 147: 138 Chapter 5 Backscattered electro
Page 148 and 149: 140 Chapter 5 Whereas Ip remains co
Page 150 and 151: 142 Chapter 5 Figure 5-14. Red, gre
Page 152 and 153: 144 Chapter 5 the SE2 and SE3 compo
Page 154 and 155: 146 Chapter 5 just-observable loss
Page 156 and 157: 148 Chapter 5 Section 4-10. Films o
Page 158 and 159: 150 Chapter 5 A backscattered-elect
Page 160 and 161: 152 Chapter 5 One example of this p
Page 162 and 163: Chapter 6 ANALYTICAL ELECTRON MICRO
Page 164 and 165: Analytical Electron Microscopy 157
Page 186 and 187: 180 Chapter 7 7.2 Aberration Correc
Page 188 and 189: 182 Chapter 7 Besides decreasing th
Page 190 and 191: 184 Chapter 7 7.4 Electron Holograp
Page 192 and 193: 186 Chapter 7 There are now many al
Page 194 and 195: 188 Chapter 7 holography could ther
Page 196 and 197: Appendix MATHEMATICAL DERIVATIONS A
Page 198 and 199: Mathematical Derivations 193 A.2 Im
Page 200 and 201: REFERENCES Binnig, G., Rohrer, H.,
Page 202 and 203: INDEX Aberrations, 3, 28 axial, 44
Page 204 and 205: Index 199 EELS, 172 Electromagnetic
Page 206 and 207: Index 201 Principal plane, 32, 80 P
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