  We propose a simple formula for fitting the electron mean free paths in
solids both at high and at low electron energies. The free-electron-gas
approximation used for predicting electron mean free paths is no longer valid
at low energies (E < 50 eV), as the band structure effects become significant
at those energies. Therefore we include the results of the band structure
calculations in our fit. Finally, we apply the fit to 9 elements and 2
compounds.
