title: Calculation of transition probability for neutralization process of +1 ion based on the Noziéres and Dominicis theory.
abstract: We investigate the neutralization probability of a +1 ion moving parallel to a metal surface, mainly using the Noziéres and Dominicis theory (ND theory), which was applied to the edge singularities in x-ray absorption and emission spectra in metals. In particular, we focus on the effects due to the sudden disappearance of the image potential in the neutralization process. From the analysis, we found that the neutralization probability is given by [Formula: see text], where D and Γ are the band width and the gamma function. The factor α = 2δ/π-(δ/π)(2) is given by the phase shift (δ: phase shift on Fermi surface), and the energy difference between the initial and final states, Δ, includes the kinetic energy of the ion and various other phenomenological factors. The singularity caused from the sudden disappearance of the image potential enhances or reduces the neutralization probability depending on the symmetry of atomic orbital of the ion. When the ion velocity is too fast to form an image potential, the neutralization process would proceed without the creation of an image potential, accompanying an excitation of a surface plasmon; as a result of plasmon excitation the ion velocity becomes slower than the plasma frequency because of screening effects. In this paper, we apply the ND theory to the case of slow ion motion and discuss the dynamics.
authors.affiliation: Department of Materials Science and Engineering, Nagasaki University, Nagasaki, Japan.
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Kondo
authors.forename: Kosaku
authors.initials: K
authors.lastname: Yamada