It was proposed by August and Wernisch  that backscattering coefficient (η) of electrons can be given by,
This analytical expression was derived with good fit to experimental data, especially with regard to low electron energies. Figure 4564a shows the comparison of backscattering coefficient between experimentally fitted Equation and Monte Carlo (MC) simulation for C, Si, and Cu. Good agreement is
obtained to within 10% of the analytical expression. η can be further classified to
coefficients of elastic backscattering electrons and coefficients of inelastic backscattering electrons.
Figure 4564a. Comparison of backscattering coefficient between experimentally fitted Equation
and Monte Carlo (MC) simulation for C, Si, and Cu .
 H. J. August and J. Wernisch, Phys. Status Solidi 114, 629 (1 989).
 C. L. Lee and C. K. Ong, Bethe Ionization Cross-sections: a Quantitative Survey on Calculating the Backscattering Factor in AES, Surface and Interface Analysis, 19, 227-231 (1992).