Accurate description of surface ionization in electron probe microanalysis: An improved formulation

A new analytical expression of the surface ionization Φ(0) is derived in terms of atomic number and overvoltage. This expression is obtained by means of an analytical description of the energy distribution of backscattered electrons. The Φ(0) data for Pt, W, Sb, InSb, Ni, Co and Mg have been measured using the tracer technique. The Φ(0) values obtained by using the new expression compare more favourably with experimental results, Monte Carlo simulation and backscattering data from the literature than those obtained with the previous analytical models.