No 5 (2023)

A brief description of the concept of a soft X-ray microscope for the Nanoscopy station is given, which is planned to be installed at the SKIF fourth-generation synchrotron. The microscope will be designed to study the structure of cells and dynamic processes in them with nanometer spatial resolution. It will use a unique absorption contrast of ~15 between carbon-containing structures and water in the spectral range of the “water transparency window”, λ = 2.3–4.3 nm, which eliminates the need for contrasting and the use of fluorophores and minimizes the doses of ionizing radiation absorbed in the samples to obtain high-quality 3D-images. The scanning and projection schemes of the microscope, their main technical characteristics, including the calculated spectra and parameters of the undulator source are presented, and an estimate of the absorbed doses depending on the resolution is obtained. The main advantage of the proposed concept lies in the use of an objective of high-aperture multilayer X-ray mirrors, which makes it possible to clearly visualize the focal section of the sample. Technically simple axial tomography will also be used to reconstruct the three-dimensional structure of frozen or dried samples. In the scanning scheme, due to the low dose of radiation, it will be possible to study living plant cells with a resolution of up to 10 nm, animals with a resolution of up to 80 nm, and cryofixed samples with a resolution of up to 5 nm. In the projection scheme, due to the simultaneous observation of the entire focal XY-section, the time for obtaining three-dimensional images is significantly reduced, but due to the large dose, it will be oriented mainly on the study of fixed samples.

The paper presents the results of a study of the effect of irradiation of the surface of a hypoeutectic silumin with a pulsed electron beam on the mechanical properties of the material. Silumin grade AK5M2 (Al–(4.0–6.0)Si–1.3Fe–0.5Mn–0.5Ni–0.2Ti–2.3Cu–0.8Mg–1.5Zn) was used as the research material. To carry out uniaxial tensile deformation, two-sided proportional samples with heads were made. The results of studying the evolution of deformation fields of layered composites silumin/CFRP for uniaxial tension based on irradiated silumin are also presented. The carbon fiber is made of a filler – carbon unidirectional fabric FibARM Tape-230 – and a binder – a two-component epoxy compound FibARM Resin 530. The fracture surface of the samples was studied using scanning electron microscopy techniques. The dependences of the maximum and minimum values of strains in the localizers on the sample surface on the averaged strains over the working area of the sample are plotted. An increase (relative to silumin in the initial state) in the strength and plastic properties of both samples of irradiated silumin and of the silumin/CFRP composite was determined. A sawtooth character of the deformation curve of uniaxial tension of the composite material silumin/carbon fiber with a pre-irradiated surface of the silumin plate is revealed.

The results of studies of the optical properties and structure of In₂O₃ films on Al₂O₃ (012) substrates deposited by dc-magnetron sputtering are summarized. The investigated films differ in the deposition time, substrate temperature, and the presence of additional heat treatment in air. According to X-ray diffraction measurements, these films show a reflex, which correspond to the (222) plane of the cubic modification of In₂O₃. Its exact position and half-width depend on the deposition time. The optical properties of the obtained films are explained by the microstructure, which is inhomogeneous in thickness and formed during the sputtering of a target with a relatively low mechanical strength. Thus, the refractive index of films deposited on substrates at room temperature increases in the direction from the substrate to the external interface. At a substrate temperature of more than 300°C, the refractive index of the films is uniform, except for a rough layer on the surface. Heat treatment reduces the number of defects in the crystal structure of the films, and leads to densification of the film material. As a result, the inhomogeneity of the refractive index disappears and the observed band gap for direct transitions decreases. The latter result from a change in the Burstein–Moss shift in consequence of the decrease of lattice defects concentration. The band gap for “indirect” transitions (that corresponds to the true value of the band gap) is insensitive to annealing.

The review of extension of fields of applications of hybrid mode of atomic-force microscope. This mode is the main for two-probes AFM-manipulator. Various methods of upgrades of the feed back system of the AFM whose essentially improve the signal-to-noise ratio in topography mapping are presented. Additionally, successful application of wide range of probes the flexible ones such as standard W probes and glass capillaries as well as rigid probes (sapphire probes with probe tips diameters of dozens of microns) are presented as well. We show the examples of wide application of such mode in measurements of conductivity and adhesion forces of the nanowhiskers on the Si substrate. Beside this, the application of hybrid mode in micro- and nanofluidics such as formation of drops of defined volumes, replacement of drops, their devision and merging are presented. The example of different techniques of manipulations are presented. The possibility of nanowhiskers replacement with liquid flow formed by AFM-probe, i.e. avoiding the direct tip-to-nanowhisker contact, are shown.

The operation of a scanning ion-conductance microscope is based on the assumption that the ion current I(z) flowing in an electrolyte solution through the narrow aperture of a probe in the form of a glass nanopipette has a maximum saturation value away from the sample under study and decreases as the probe approaches the surface. The value of the scanning ion-conductance microscope operating current is usually chosen near the saturation current I ~ 09I_sat. However, in some cases there is an unusual behavior of the I(z) approach curve near the surface when the ion current increases as the nanopipette approaches the sample surface. The appearance of a peak on the I(z) curve as the nanopipette approaches the sample surface is what we call the “peak effect”. It is obvious that the peak effect can lead to a failure in the operation of the scanning ion-conductance microscope servo system and noise at the images getting by scanning ion-conductance microscope. In this work the appearance of a peak on the approach curve have been studied experimentally. Considering the nanopipette near the sample surface as a microfluidic system in the form of a T – shaped channel the I(z) dependence using the finite element method and the СOMSOL software package have been calculated.

The development of modern technologies, including nanotechnology, is based on application of diagnostic methods of objects used in technologies processes. For this purpose most perspective are methods realized in a scanning electron microscope. Thus one of basic methods is the measurement of linear sizes of relief structures of micrometer and nanometer ranges used in micro- and nanoelectronic. In a basis of a scanning electron microscope job the secondary electronic issue of firm body lays. However, practically all researches were spent on surfaces, which relief was neglected. The review of theoretical and experimental materials to researches of a secondary electron emission is given. Practically all known laws are checked up in experiments and have received the physical explanation. However, the application of a secondary electronic emission in a scanning electron microscopy, used in micro- both nanoelectronic and nanotechnology, requires knowledge of laws, which are shown on relief surfaces. Is demonstrated, what laws can be applied in a scanning electron microscope to measurement of linear sizes of relief structures. Is judged necessity of an influence study of a surface relief on a secondary electron emission.

The article presents the results of the computational determination of the optimal design geometry of a certain type of quasi-neutral plasma source. The scheme of an ion source with an inductive plasma discharge formed and maintained by a radio-frequency electromagnetic field in a MHz frequency range is considered. The surface profiles optimization of the main design units – namely, gas discharge chamber and ion extraction system – was carried out via computational modelling. Calculations were carried out using the previously developed engineering model of inductive discharge in plasma. The optimization criteria are the thrust and the value of the ion current extracted from the source, determined from the calculated distributions of electron density and electron temperature within the discharge chamber. Optimization calculations were carried out for an ion source with a discharge chamber diameter of 16 cm on a type of surfaces that are segments of a spherical surface. The results of the thrust calculations are presented in relative values in comparison with the values calculated for the basic configuration of the ion source scheme with a hemispherical discharge chamber and a flat ion extraction system. A significant increase in the value of the extracted ion current and thrust in the determined optimal configuration of the ion source was obtained in comparison with the same values calculated for the basic configuration of the ion source with a hemispherical discharge chamber and flat grids of the ion extraction system.