Comparison of Electron- and Ion-induced Electron Yields and Emission Spectra

Incident charged particle beams of electrons or ions can produce electron emission from materials. Indeed, any stimulus that deposits energy in the material—including electromagnetic radiation, heat, magnetic or electric fields—can elevate electrons within the material to higher energies, sometimes ejecting them from constituent atoms and even emitting them from the material. The secondary electron yield is the ratio of the emitted electrons to incident electrons or ions. Note that there can also be quasielatically scattered particles that are backscattered. The resulting electron yield curves and electron emission spectra depend on the incident particle species, their incident energies, the impacted materials, and energy transfer processes between the incident particles and the material. This presentation compares and contrasts electron yield curves and electron emission spectra for incident electrons to those for Nobel ions of different masses and charge-to-mass ratios. Data for conducting materials are modeled with simple Bethe/Sternglass theories dominated by more elastic collisions for ion scattering and with semi-empirical reduced power law models for electron scattering dominated by more inelastic collisions. Scaling laws are considered based on incident masses and penetration depths. The effects of contamination and surface roughness are also compared.