Secondary electron coefficient δ = # SE / # incident beam electrons Dependent on atomic number if λ = mean free path maximum emission depth ~ 5λ For metals:λ ~ 1nm abundant conduction band electrons lots of inelastic scattering of SE Insulators: λ ~ 10 nm Information depth for SE ~ 1/100 of BSE About 1% of primary beam electron range (Kanaya-Okayama range)
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