Auger Neutralization of Slow Protons at Solid Surfaces

Auger neutralization of slow protons (⪅ a few keV) scattered from solid surfaces is considered. The neutralïzation probability per unit time P(s) is calculated as a function of the proton distance s from the surface to P(s) = A{e^−2xs + (Bs + C) e −(x+a 0 −1)s + (Ds² + Es + F) e −2a 0 −1s}, where a₀ is the Bohr radius and A, B, C, D, E, F, and x proper constants depending on the target. At large distances from the surface, the second and third terms of P(s) can be neglected. As the proton approaches the surface, however, P(s) deviates from the simple exponential dependence of s. The neutral fraction φ⁰ is also calculated. From the obtained φ⁰, it is shown that Auger neutralization is important, at least in the low energy region.