1 Answers
The inelastic mean free path is an index of how far an electron on average travels through a solid before losing energy.
If a monochromatic primary beam of electrons is incident on a solid surface, the majority of incident electrons lose their energy because they interact strongly with matter, leading to plasmon excitation, electron-hole pair formation, and vibrational excitation. The intensity of the primary electrons, I 0 {\displaystyle I_{0}} , is damped as a function of the distance, d, into the solid. The intensity decay can be expressed as follows:
where I {\displaystyle \textstyle I} is the intensity after the primary electron beam has traveled through the solid to a distance d {\displaystyle \textstyle d}. The parameter λ {\displaystyle \textstyle \lambda } , termed the inelastic mean free path , is defined as the distance an electron beam can travel before its intensity decays to 1 / e {\displaystyle \textstyle 1/e} of its initial value.
The inelastic mean free path of electrons can roughly be described by a universal curve that is the same for all materials.