Secondary electrons

They develop due to inelastic primary electron (PE) distribution and are present immediately at the surface area of the impacting primary electron beam. They have an energy value of

Additional references:

Electron microscope
Electron microscopy
Electron probe micro analysis
Energy dispersive x-ray spectrometry
Scanning electron microscopy
Back-scattered electrons
Wave-length dispersive x-ray spectrometry

Literature:

Schröttner H. : Die Elektronenmikroskopie in der Materialforschung / Electron Microscopy in Materials Research.