Interaction of slow highly charged ions with a metal surface covered with a thin dielectric film. The role of the neutralization energy in the nanostructures formation

Effect of the cascade neutralization energy on the surface modification by the impact of slow highly charged ions

“…For the metal surface parameters, within the Sommerfeld model, we use the value of the work function φ = 5eV and for the potential depth U 0 = 15eV. The dielectric film is characterized by the width s 0 , and by the dielectric constants = 2, 4 and 8.We analyze the arbitrary collision geometry for the angles of incidence Φ in = π/2, 3π/8 and π/4.Due to the interaction of the HCI with solid surface the ionic charge decreases in time according to the cascade neutralization scenario Q = Z → Z − 1 → .... → Q fin , see The neutralization process in the MDV-system we treat within the framework of the TVM and micro-staircase model (Majkić et al, 2017(Majkić et al, , 2019. According to the TVM the state of the active electron e − is described by two state vectors |Ψ 1 (t) and |Ψ 2 (t) , which simultaneously evolve in two opposite directions of time.…”

“…The states of the active electron at the time t (at ion-surface distance R) between the initial time t in and the final time t f in are expressed via intermediate eigenstates |µ M (R) and |ν A (R) of the in-HamiltonianĤ 1 (R) and the out-HamiltonianĤ 2 (R), respectively (Nedeljković et al, 2012;Nedeljković et al, 2016). By the ap-propriate expressions of the HamiltoniansĤ 1 (R) andĤ 2 (R) we take into account the polarization of the metal surface and the polarization of the ionic core, respectively, as well as the effect of the dielectric film (Majkić et al, 2017). The corresponding eigenenergies are E M = −γ 2 M /2 (γ M is the continous energy parameter) and…”

“…During the ion-surface interaction, the electrons from the surface are captured into the intermediate ionic Rydberg states, which results in the neutralization cascade. The cascade neutralization energy has an important role in the surface modification, i.e., in the formation of different types of the surface nanostructures (Majkić et al, 2017). That is, the size of the created features is in a direct correlation with the ionic neutralization energy.…”

“…However, for moderate ionic velocities, the surface modification is governed by the ionic neutralization energy which is less than the potential energy due to the incomplete neutralization. In that case, both the neutralization and the deposited kinetic energy contribute to the surface modification (Majkić et al, 2017(Majkić et al, , 2019.…”

“…For the sake of simplicity, first we calculate the neutralization energy in the absence of dielectric film (metal-vacuum MV-system). The cascade neutralization energy, in the presence of dielectric film (metal-dielectric-vacuum, MDV-system), we calculate by using the principle of equivalence (Majkić et al, 2017), which correlates the quantities in the MVand the MDV-system via the concept of the effective core charge. The second aim is an analysis of the role of the cascade neutralization energy in the surface modification.…”