secondary ionization

chemistry and physics

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July 13, 2026

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Secondary ionization is a process in chemistry and physics where energetic particles, such as electrons or ions, cause further ionization of atoms or molecules. This occurs after an initial ionization event. For instance, when charged particles or X rays pass through matter, they can eject electrons. These ejected electrons, if they possess sufficient energy, can then collide with other neutral atoms or molecules, knocking out additional electrons and thus creating more ions. This cascading effect is crucial in phenomena like the operation of photomultiplier tubes and image intensifiers, where a small initial current is amplified. Secondary ionization is also a key process in plasma formation and is utilized in techniques like secondary ion mass spectrometry for surface analysis.1234

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delta ray
…the energetic electrons that cause secondary ionization and are referred to as delta rays. On a developed photographic emulsion, in which strongly ionizing particles have left dense tracks, delta rays appear as thin wavy spurs or branches. The term delta ray, first used by the British physicist J.J. Thomson, is…
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…the energetic electrons that cause secondary ionization and are referred to as delta rays. On a developed photographic emulsion, in which strongly ionizing particles have left dense tracks, delta rays appear as thin wavy spurs or branches. The term delta ray, first used by the British physicist J.J. Thomson, is…
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radiation measurement
Proportional counters
…energy between collisions to cause secondary ionization in the gas. After such an ionizing collision, two free electrons exist in place of the original one. In a uniform electric field under these conditions, the number of electrons will grow exponentially as they are drawn in a direction opposite to that…
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…energy between collisions to cause secondary ionization in the gas. After such an ionizing collision, two free electrons exist in place of the original one. In a uniform electric field under these conditions, the number of electrons will grow exponentially as they are drawn in a direction opposite to that…
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spectroscopy
Sputter atomization
…a solid, neutral atoms and secondary charged particles are ejected from the target in a process called sputtering. In the secondary ion mass spectrometry (SIMS) method, these secondary ions are used to gain information about the target material (see mass spectrometry: Secondary-ion emission). In contrast, the sputter-initiated RIS (SIRIS) method
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…a solid, neutral atoms and secondary charged particles are ejected from the target in a process called sputtering. In the secondary ion mass spectrometry (SIMS) method, these secondary ions are used to gain information about the target material (see mass spectrometry: Secondary-ion emission). In contrast, the sputter-initiated RIS (SIRIS) method
Read More