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SEM & TEM - Coggle Diagram
SEM & TEM
Scanning Electron Microscope (SEM)
Sample Preparation:
Function of the vacuum
: remove moisture in scanning the image accurately and preventing any impurities/gas decomposition forming in the chamber.
Working Principle;
Secondary Electron imaging (SEI)
Inelastic scattering
Step 1: Electron Gun emits electrons
Step 2: Inelastic collision is observed. Evident by the primary electron knocking onto the electrons
Step 3: Vacancy is formed and is occupied by the higher energy electron
Step 4: Knocked electrons (Secondary) goes to the detector and image is formed.
Backscatter Electron Imaging (BEI)
Step 2: Elastic Collision is observed. Evident by the primary electrons being unable to knock onto the eixting
Step 3: This backscattered electron gets attracted to the nucleus and moves about the atomic radius
Step 1: Electron Gun emits electrons
Step 4: Backscattered electrons (Primary) goes to the detector and the image is formed
Observed result: Morphology, Topography & Composition
Background of Materials
Topographical imaging
non-conductive
carbon evaporator
gold/platinum coating
Compositional imaging
non-conductive
carbon coating
Tranmission Electron Microscope (TEM)
Working Principle:
diffracted beam
Dark field
transmitted beam
High Resolution
Bright field
