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

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Analytical Electron Microscopy 175 Figure 6-10. Electron energy-loss spectrum of a high-temperature superconductor, showing N- and M-shell ionization edges of barium, the K-ionization edge of oxygen, and weak ionization edges from copper and yttrium. The plasmon peak represents inelastic scattering from valence electrons. A logarithmic vertical scale has been used in order to accommodate the large range of electron intensity. Courtesy of D.H. Shin (Ph.D. thesis, Cornell University).
Chapter 7 RECENT DEVELOPMENTS 7.1 Scanning Transmission Electron Microscopy In Section 1.6, we noted that a field-emission STEM was the first instrument to successfully image single atoms in the late 1960’s. Several years later, a “dedicated STEM” (operating only in scanning mode) was manufactured by the Vacuum Generators Company in the UK. A cross-sectional diagram of a substantially modified version of this instrument (at IBM Watson Research Laboratories) is shown in Fig. 7-1. Because there is no need for a viewing screen inside the lens column, its electron gun is located at the bottom of the instrument (with some advantage in terms of mechanical stability) and the electron detectors are on top (making it easier to modify the detectors or add new ones). Most STEM images are recorded in dark-field mode, using an annular dark-field (ADF) detector located just above the specimen. Its design is similar to that of a Robinson or solid-state BSE detector used in the SEM (Fig. 5-10) but it collects electrons that are transmitted through the specimen and scattered within a certain angular range (�min to �max), determined by the inner and outer diameters. By making �min large, only large-angle (mainly elastic) scattering is collected. According to Eq. (4.15), its intensity is proportional to Z 2 . Therefore the ADF image contains strong atomic-number contrast and not much diffraction contrast (most of the diffracted electrons have a scattering angle less than �min and pass through the central hole in the detector). Although the signal is weak, the annular detector design provides high collection efficiency, as all azimuthal angles of scattering are recorded (unlike the case of dark-field imaging in a conventional TEM).
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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
Page 132 and 133: 124 Chapter 4 The procedures outlin
Page 134 and 135: 126 Chapter 5 specimen scan coils o
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 184 and 185: 178 Chapter 7 Figure 7-1. Modified
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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