A novel approach to derive absorption coefficient of secondary electrons as applied to Ti and TiO2

A novel approach is proposed to derive a theoretical curve, S(Ep), from the equation S(Ep) = k∫ ∞ 0 [dE/dz] Ep × e -αz dz for construction of a database of the secondary electron emission (k, a), where S(Ep) and [dE/dz] EP are the secondary yield and energy dissipation in depth, respectively, for incident electrons of primary energy, Ep. a is the absorption coefficient of the secondary electron and k the secondary emission coefficient of the specimen. This approach is based on the use of the theoretical energy dissipation in depth [dE/dz] EP , which is to be obtained from Monte Carlo calculation, and the experimental δ ex (E P ) or a set of δ m and E m to be measured in experiment, where δ m is the maximum secondary yield obtained at primary electron energy E m . Comparing the theoretical S(Ep) with the experimental δ ex (E P ) or a set of δ m and E m one can obtain the best-fit value of a and, then, k. Since data-sets of δ m and E m have been reported for a wide variety of materials so far, the proposed approach enables us to derive the a and k values for the materials of practical interest, filling up the deficiency of reliable data on the secondary emission. This approach was verified by applying it to Be, Ag, Pt and Bi, of which δ m and E m have been published, leading to the confirmation that α-values derived by the present approach agree very well with the experimental ones. Experiments was also performed to measure S(Ep) for Ti and TiO 2 to obtain a and k-values. The results are a -1 ≅ 0.5 nm and k ≅ 0.046, for Ti, α -1 ≅ 0.7 nm and k ≅ 0.028 for TiO 2 .