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Interaction potentials were obtained by the density functional theory (DFT) and nuclear stopping powers (NSP) were calculated for 48 systems in the energy range above 10 eV. It was shown that NSP calculated using the DFT potentials in the collision energy range of 10–1000 eV give more accurate values comparing with the SRIM data, obtained data differs from SRIM data by 15–70%. The presence of a potential well leads to the emergence of an additional NSP peak at low energies. Comparison of classical calculations of the transport cross section with semiclassical ones showed their identity at energies of up to 1 eV. The criterion for the applicability of classical calculations for the transport cross section and NSP cross sections is the condition l>1 (l is the angular momentum). The importance of including multichannel scattering in NSP calculations was demonstrated, for the case of energies below 20 eV.

A universal dependence (scaling) is proposed for estimating the cross sections for the production of K-vacancies in collisions of keV ions and atoms. The scaling is based on the studies of the spectra of inelastic losses, emission cross sections of characteristic Auger electrons, and radiation in the decay of K-vacancies. A formula is suggested for collisions of atoms with $$Z > 10$$ , which explains the ionization of the K-shell by the transitions due to the superpromotion of terms. The scaling phenomenon makes it possible to estimate the cross sections for the production of K-vacancies for as yet unexplored cases of atomic collisions and to approximately find in this way possible electron stopping powers in passage of ions through a solid body. It can also be used to determine the composition of matter under ion irradiation.

The electronic stopping losses for p–He and p–Ar systems are compared with independent measurements of cross sections for elementary processes. It is shown that quantitative agreement can be reached if the fact that significant energy losses are carried away by knocked-out electrons is taken into account. The dependence of the average energy of knocked-out electrons on the impact velocity for velocities that are smaller than 1.5 a.u. can be described within the framework of dynamic ionization theory. It is established that the equilibrium charge of beam particles depends on the ratio of the stripping and charge-exchange cross sections, and the use of frequently applied universal models for description of the equilibrium charge in the case under consideration is not justified. It is shown that the contribution of excitation processes for the studied cases does not exceed 7–12%, which differs from traditional concepts of equality between the contributions of ionization and excitation processes. The inclusion of multiple ionization processes, which increases the electronic stopping power by 6% in the case of p–He and by 23% in the case of p–Ar, turns out to be important.

The exponential component of the electron spectrum during Ne–Ne collisions is shown to be associated with the electron transitions from the autoionization term to the continuum. The characteristics of this term have been determined. The exponential shape of the spectrum is explained by the absence of interference between the transition amplitudes as the particles come close together and fly apart due to a high transition probability. For Auger transitions in the quasi-molecule we have determined the dependence of the mean Auger transition energy on the reached internuclear distance, which agrees well with the results of energy level calculations for the Ne–Ne system, and the dependence of the weighted mean Auger transition probability on the observed electron energy Ee. We show that the transition probability decreases significantly with increasing Ee as the internuclear distance decreases, apparently, due to a decrease in the overlap integrals of the wave functions for the interacting electrons. Our analysis allows a coherent picture of ionization in collisions of intermediate-mass ions with keV energies to be formed.

It is shown that the excitation of autoionization states during the collisions of keV-energy ions with a solid plays a determining role in the formation of inelastic energy losses and, accordingly, the electronic-stopping cross section Se. It is proposed to estimate the Se values using the relationship between the cross section for autoionization-state excitation and the ionization cross section. For cases where the ionization cross sections are unknown, scaling is used to calculate the ionization cross sections when the L and M shells are excited. The threshold dependence of Se versus the energy of bombarding ions is predicted.

A model for estimating the contribution of autoionization state formation to inelastic energy losses in collisions of keV-energy ions with solids is proposed. Using the suggested scaling for L and M shell excitation it is possible to estimate the ionization cross sections and the contribution of the ionization processes to the electronic stopping power dE/dx. The model predicts a threshold behavior of dE/dx. In the cases studied the formation of autoionization states gives important contribution to the value of dE/dx.

Multiple scattering at grazing angles of incidence is shown to affect the value of inelastic energy loss determined from the position of the quasi-single scattering peak on the energy scale.

The paper suggests a scaling for calculating cross-sections of L-vacancy formation due to atomic collisions in the keV range of collision energies. A technique for estimating the probability of inelastic transition by differentiating its cross-section dependence on the collision energy is also proposed.

We have performed a theoretical investigation of the possibility of laser action on the innershell 0–1 (2s–2p) transition of Ne-like ions. The plasma conditions for the effective lasing are found. Here we present atomic-kinetic calculations for gain values along the Ne-like sequence; the regularities along the sequence are drawn. These data are important for the experimental observations of X-ray laser effects.

The probability of single-photon decay of highly excited double hole state of atoms is considered. The concrete calculations are performed in the lowest order of perturbation theory in interelectron interaction for states (2s)-2 in Ne, (2s)-2 and (2p)-2 in double ionized Ar−Ar++ and (4d)-2 in Xe.