The dark areas in the image are due to which phenomenon?

• A. Deflected electrons
• B. Absorbed photons
• C. Scattered light
• D. Phase shifts

Answer: (A)

In electron imaging, image contrast comes from how many electrons actually reach the detector. Dark areas appear where the beam is removed from the detected signal, usually because the electrons are scattered out of the transmitted beam by denser or heavier regions. When electrons are deflected away, fewer of them contribute to the image, so that region looks darker. This is a primary reason for contrast in many electron microscopy images—the more scattering or deflection a region causes, the darker it appears. Absorbed photons or scattered light relate to light-based imaging and wouldn’t explain dark areas in an electron image, and phase shifts influence contrast in specific phase-contrast techniques rather than producing dark regions by themselves.