No 1 (2023)

For the first time, binary and ternary complexes of fullerenes and diphthalocyanines of europium with detonation nanodiamonds have been obtained, which can serve as platforms for the delivery of these hydrophobic molecules into aqueous biological media for the tasks to improve magnetic resonance imaging, photodynamic therapy, and diagnostics using luminescent labels. Detonation nanodiamonds (size ~4–5 nm) had a positive potential (30–70 mV) in an aqueous medium due to groups (CH, COH) grafted onto the surface as a result of heat treatment in a hydrogen atmosphere. During the interaction of positively charged diamonds with electronegative hydrated fullerenes in an aqueous medium, the initial aggregates of each of the components were destroyed, and their electrostatic bonding led to the formation of stable compact complexes ~20 nm in size according to the data of dynamic light scattering and small-angle neutron scattering in colloids under normal conditions (20°С). Binary complexes included, on average, two fullerene molecules per 30–40 diamond particles. The introduction of diphthalocyanine molecules into a binary colloid resulted in the formation of stable ternary structures. The obtained complexes of diamonds, fullerenes, and diphthalocyanine molecules are promising for biomedical applications due to the luminescent and magnetic properties of the components.

The features of the electronic and local atomic structure of erbium metalloporphyrins Er(acac)TPPBr₈, Er(acac)TPP and precursor tetraphenylporphyrins (TPP and TPPBr₈) have been studied by X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. Using photoelectron spectroscopy, the structure parameters of the Er4d, N1s, C1s, O1s, Br3d core levels and the valence band have been determined. The nature of the change in the electronic structure of tetraphenylporphyrins upon the introduction of the central erbium atom has been established – a uniform redistribution of the electron density between the nitrogen atoms of the pyrrole and aza groups. From the analysis of the X-ray absorption spectra, the effect of bromine addition in the meso-position of the macrocycle on the parameters of the local atomic structure of the erbium porphyrin complex has been established, and the integer trivalent state of the metal (Er³⁺) in rare-earth metalloporphyrins has been confirmed.

Radiation physics of the 21st century, which combines the special physical properties of materials and objects (nanoobjects, fractals, and others) with strong non-equilibrium, demonstrates many unusual nonlinear effects and their interpretation. This is especially evident in the case of high-intensity irradiation of various natures with a wide energy spectrum. Taking into account five different channels for the transfer of radiation energy to matter (elastic scattering, ionization, heat release, elastic and shock waves) makes it difficult to see the number of new unusual combinations of the radiation responses, the study of which at the present stage, apparently, is possible using the concept of “complexity”. Among the various characteristics of irradiated objects, a special role is played by the hierarchy of their structure, which is fundamentally important for objects of both inanimate and living nature. The peculiarity of including objects of a hierarchical structure in the analysis of radiation effects leads to a new situation – the involvement of the ideas of cybernetics in radiation physics. Questions of a new type arise concerning the relationship between radiation and information, in particular, the influence of the entire variety of radiation parameters (energy, intensity, and dose) on the transfer of information from the lower platform of hierarchical structures to higher ones and its compression at the same time. The solution of these problems requires the use of both new theoretical approaches and the modification of traditional schemes in relation to the elementary acts of atomic rearrangements, such as kinetics and approaches to revealing the mechanisms of radiation effects. This range of questions has been formulated, and a certain solution has been obtained in relation to objects of inanimate and living nature.

The influence of high-field electron injection modes on the charge state and defectiveness of metal–oxide–semiconductor (MOS) structures after irradiation is studied. It is shown that to erase the radiation-induced positive charge accumulated in the SiO₂ film of MOS structures, it is necessary to apply high-field Fowler–Nordheim tunnel injection of electrons in electric field that do not cause the hole generation. It has been established that erasure of the radiation-induced positive charge in the SiO₂ film of MOS structure and the generation of new interface traps are mainly determined by the magnitude of the charge injected into the dielectric. It has been found that, upon annihilation of the holes trapped in SiO₂ as a result of the interaction with the injected electrons, a significant increase in the number of the interface traps is observed, which significantly exceeds the number of interface traps arising upon annealing of a radiation-induced positive charge at room temperature. A model is proposed that describes the annihilation of a radiation-induced positive charge upon interaction with injected electrons.

The effect of high-power pulsed laser irradiation generated in a GOS 1001 installation in the Q-switched mode (power density q = 1.2 × 10¹² W/m², pulse duration τ₀ = 50 ns, number of pulses N = 1–4) in vacuum on a porous structure of the vanadium sample surface is studied, as well as on its hardness determined in two ways based on the recovered print method and on the kinetic indentation method. The porous structure is formed during implantation of helium ions (energy 30 keV, dose 2.0 × 10²³ m^–2, ion flux density 4.8 × 10¹⁸ m^–2 · s^–1, temperature ~500 K). It is shown that irradiation with helium ions causes vanadium hardening by about a factor of two, and the microhardness values determined by the recovered print method are slightly lower than the kinetic hardness values. It is found that in both cases, as a result of the target destruction under the laser radiation, a crater appears, surrounded by a breastwork, behind which there is a zone of thermal influence. Erosion is observed in this zone, caused by the destruction of the domes of bubbles-blisters filled with implanted helium and impurity atoms (C, O, N) present in the liquid metal. It is found that with an increase in the number of laser pulses, the microhardness in the crater decreases, while the narrow area around it hardens, and with further distance from the crater, the microhardness approaches values corresponding to that of vanadium implanted with helium ions.

The electronic exchange between an atomic particle (a charged ion or a neutral atom) and a metal surface containing a defect in the form of an atomic step has been studied. The research tool is three-dimensional computer modeling. A model static problem is considered when the particle is fixed above the surface. Calculated data are obtained on the dependence on the distance to the surface and the lateral position of the particle of the main parameters of charge exchange: the energy position and the width of the particle level (which determines the efficiency of the electronic exchange).

A model of glow gas discharge in the presence of a thin insulating film on the cathode is formulated. It takes into account that under discharge current flow, due to the bombardment of the cathode by ions, positive charges accumulate on the film and generate strong electric field in it. As a result, field emission of electrons from the cathode metal substrate into the film starts, which, with an increase in its temperature, transforms into thermal-field emission. Electrons move in the film, being accelerated by the electric field and decelerated in collisions with phonons, and some of them leave the film into the discharge, increasing the effective ion-electron emission yield of the cathode. The electric field strength in the film is determined from the condition that the density of the discharge current and the density of the emission current from the cathode metal substrate into the film are equal. The dependences of the film emission efficiency, the effective ion-electron emission yield of the cathode, and the discharge characteristics on the cathode temperature are calculated. It is shown that already at a temperature exceeding room temperature by several hundred degrees, the temperature enhancement of field electron emission from the metal substrate into the film can noticeably influence the cathode emission properties and the discharge voltage-current characteristic.

Some features of the charge transfer between ions and the metal surface, which are due to its atomic structure, were numerically investigated. The simulation was based on a three-dimensional implementation of the wave packet propagation method. The studied system consisted of an Al(110) metal surface and an excited hydrogen atom with an electron in the p-state, which does not have spherical symmetry. When considering a model static problem, it was shown that electron exchange is more efficient when the symmetry axis of the p-orbital was oriented perpendicular to the Al surface, rather than parallel. Also, analysis of the obtained data showed that the time dependence of the atomic population function has an exponential decay. The solution of the “dynamic” problem showed that for an excited hydrogen atom moving along the metal surface, the electron exchange does not depend on the orientation of the p-orbital symmetry axis with respect to the direction of motion of the atom. The study of the dynamics of the charge transfer with a metal surface made it possible to observe for p-orbitals, the symmetry axis of which was directed parallel to the metal surface, the separation of the electron density passing to the surface into two parts, which diverge relative to the p-orbital symmetry plane.