SECONDARY-ELECTRON EMISSION FROM MAGNESIUM-OXIDE

Investigations of secondary-electron (SE) emission from magnesium oxid e smoke cubes have been made in coincidence with different primary-ele ctron beam losses and geometrical configurations. For aloof-beam situa tions at distances of up to 10 nm outside the cube, SEs are observed i n coincidence with surface excitations of the valence electrons. For b eams which penetrate the cube, additional SEs arise following either a tomic core excitation or, with somewhat lower probability, bulk valenc e excitation.