Image Contrast Mechanisms and Topology of Polyethylene Single Crystals: Low-Voltage, High-Resolution Scanning Electron Microscopy and Atomic Force Microscopy
Polyethylene (PE) single crystals were chosen to study the interaction of low energy (0.8 – 5 keV) electron beams with polymeric materials using a low-voltage, high-resolution scanning electron microscope (LVHRSEM). The charge contrast mechanism was investigated as a function of the conductivity of the substrates, the accelerating voltage, and the sample thickness (from monolayer to multilayers). Comparison of a series of substrates from insulators (such as mica) to conductors (such as aluminum) showed a wide range of image contrast. The best contrast case was PE on carbon film on copper grids (normally used for transmission electron microscopy (TEM)) at an accelerating voltage of 1 kV. The effect of the incident voltage on sample contamination and radiation damage of PE samples was also studied. In addition, topological features of PE single crystals as observed by atomic force microscope (AFM) were compared with the results from LVHRSEM.
KeywordsAtomic Force Microscopy Atomic Force Microscopy Image Electron Yield Contrast Mechanism Conventional Electron Microscopy
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