Collisions of electrons with atoms
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Quantised energy transfer

Quantised energy transfer

Energy-level diagram showing a free electron with 6.7 eV exciting an atom to a level 4.9 eV above ground, leaving 1.8 eV kinetic energy and emitting a photon on de-excitation

Atoms have discrete energy levels, so a free electron cannot give an atom just any amount of energy in a collision. Energy is transferred in fixed amounts that match the gaps between allowed levels.

Collisions of electrons with atoms Lesson

  1. A Level
  2. /Physics
  3. /Collisions of electrons with atoms