Figure 2.

Attenuation lengths of electrons in solids as a function of their energy. An early compilation (17) of a variety of experimental data are given by the dots. An interpolation formula is shown by the solid line. At the time that these data were compiled, the attenuation lengths were regarded as identical to the inelastic collision mean free paths, although later it was realized (18) that these quantities could differ by roughly 50%. [Adapted from Seah and Dench (17) with permission.]