Each imaging system operates on different principles:
- SEM: An electron beam scans the sample surface, and secondary electrons emitted from the sample are collected to form an image. The interaction of the beam with the sample provides information about its surface morphology and composition. - TEM: A high-energy electron beam passes through a very thin sample. The transmitted electrons are collected to form an image, revealing internal structures at atomic resolutions. - AFM: A sharp tip attached to a cantilever scans the sample surface. The deflection of the cantilever due to forces between the tip and the sample is measured, providing topographical data. - STM: A voltage is applied between a sharp tip and the sample, causing electrons to tunnel through the vacuum gap. The resulting tunneling current is measured to construct an image with atomic precision.
