The Malter effect is named after Zachary Malter, who first described the effect. Following exposure to ionizing radiation

Ionizing radiation

Ionizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...

 (e.g., electrons, ions, X-rays, extreme ultraviolet

Extreme ultraviolet

Extreme Ultraviolet radiation is high-energy ultraviolet radiation, generally defined to be electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths from 120 nm down to 10 nm, and therefore having photons with energies from 10 eV up to 124 eV...

, vacuum ultraviolet), secondary electron emission from the surface of a thin insulating layer results in the establishment of a positive charge on the surface. This positive charge produces a high electric field

Electric field

In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...

in the insulator, resulting in the emission of electrons through the surface. This tends to pull more electrons from further beneath the surface. Eventually the sample replenishes the lost electrons, by picking up the collected secondary electrons through the ground loop.