Transmission Electron Microscopy B 电子光学基础 1
Transmission Electron Microscopy 1 电子光学基础
电子光学基础 。电子波与电磁透镜 。电磁透镜的像差与分辨率 电磁透镜的景深和焦长 Water-cooled surface Electron ray paths Water SPower Soft Fe pole pieces C coils 2
电子波与电磁透镜 电磁透镜的像差与分辨率 电磁透镜的景深和焦长 电子光学基础 2
Frequency in Wavelength cycles per second in nm 106- m 400- 1020- Gamma rays Violet One angstrom 10 450 Indigo One nanometer X-rays 500- Blue Ultravioler Green 105 One micrometer Visible Light Yellow 10 Infrared 600 Orange s子 One centimeter 00 Red 1010- Short radio waves One meter Short radio waves 109 750 Broadcast band One kilometer 105 Visible Light:~6000 A 10 Long radio waves X-rays: λ0.5-2.5A Electrons: 10.05A 3
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电子束与固态样品相互作用 SEM Incident high-kV beam Secondary electrons (SE) Backscattered electrons (BSE) Characteristic X-rays EDS/WDS Auger Visible electrons Light Absorbed' Electron-hole electrons pairs Bremsstrahlung Specimen X-rays Elastically Inelastically scattered Direct scattered electrons Beam electrons 4 TEM
4 EDS/WDS SEM 电子束与固态样品相互作用 TEM
透射电子显微镜 ..3/ m 品lte iayMarch 9,1931 1938 Sketch of 1st TEM 1st commercial TEM by Siemens 5 第一台电子显微镜by Ruska in1930s
透射电子显微镜 第一台电子显微镜by Ruska in 1930s March 9, 1931 1938 5 Sketch of 1st TEM 1 st commercial TEM by Siemens
Why electron microscope? Higher resolution in EM than you can in OM. Simultaneous analysis of morphology, composition and structure. SEM micrographs 1400X (e) 1400X TEM HRTEM micrograph micrograph 2800X LOM micrographs 四 6
Why electron microscope? • Higher resolution in EM than you can in OM. • Simultaneous analysis of morphology, composition and structure. 6
显微镜工作原理 灯 (光源)的 电子源 玻璃凸透镜 ☒ 聚光镜 ☒ 样品 样品 00 0 偏向线圈 物镜 ☒ ☒物镜 扫描 二次电子探头 样品 投影凸透镜 ☒ ☒ 投影镜 0 00 CRT 像 象 像 光学显微镜 透射电镜 扫描电镜 7
显微镜工作原理 7
LM Lamp TEM Electrons lllumination" Glass lens Electromagnetic lens Condenser lens Specimen Glass lens Electromagnetic lens Objective lens OM与TEM 相似性 First image Glass lens Projector lens Electromagnetic lens Eye Final image a858558 neg....m Eye Ocular Fluorescent screen 8
OM 与TEM 相似性 8
TEM成像原理 采用聚集电子束为照明源，照射试样，产生透 射电子信号 试样各区域的组织结构不同，透射电子的强度 不同，其与试样相应区域形貌、组织结构一一 对应 反映各微区组织结构特征的透射电子束，经多 级聚集放大，在荧光屏上，各微区电子强度分 布再现试样组织结构形貌 9
TEM成像原理 9 • 采用聚集电子束为照明源，照射试样，产生透 射电子信号 • 试样各区域的组织结构不同，透射电子的强度 不同，其与试样相应区域形貌、组织结构一一 对应 • 反映各微区组织结构特征的透射电子束，经多 级聚集放大，在荧光屏上，各微区电子强度分 布再现试样组织结构形貌
Electron beam Objective lens Objective aperture (back focal plane) Fixed diffraction pattern) SAD aperture Intermediate image 1 Strength→ Intermediate change lens TEM Intermediate Intermediate 衍射及成像 diffraction image 2 pattern Projector 模式 lens Fixed strength www.globalsino.com/EM/ Diffraction Final pattern Screen image (a) (b) 10
TEM 衍射及成像 模式 10