The (excess) electrons present in a specimen under electron bombardment which are led to ground and measured as specimen current. The number of absorbed electrons per unit time (or the specimen current) equals the number of primary electrons minus the number of back scattered, secondary and transmitted electrons per unit time. Therefore the fraction of electrons being absorbed depends on many parameters, including the composition and thickness of the specimen, the primary electron energy, the electron incidence angle and local electrostatic fields when present.