A. Yu. Seregin

Determination of preferential molecular orientation in porphyrin-fullerene dyad ZnDHD6ee monolayers by the X-ray standing-wave method and X-ray reflectometry

Monolayers of porphyrin-fullerene dyad molecules with zinc atoms incorporated into the porphyrin ring (ZnDHD6ee) on the surface of aqueous subphase and on Si substrates have been investigated by the X-ray standing-wave method and X-ray reflectometry. The experiments have been performed under laboratory conditions and on synchrotron radiation sources (KMC-2 station of BESSY II (Berlin) and Langmuir station at the National Research Centre “Kurchatov Institute”). Depth distributions of Zn atoms and electron density in the monolayer film are calculated. On the basis of the analysis of these distributions, it is concluded that ZnDHD6ee dyad molecules in monolayers have preferential orientation. The data obtained indicate that the molecules in monolayer film retain their orientation when the monolayer is transferred from a liquid subphase surface onto a solid substrate.

Study of the structural quality of heteroepitaxial silicon-on-sapphire structures by high-resolution X-ray diffraction, X-ray reflectivity, and electron microscopy

Heteroepitaxial silicon-on-sapphire (SOS) structures have been studied by high-resolution X-ray diffraction, X-ray reflectivity, electron microscopy, and electron diffraction. These methods yielded a large amount of complementary data on the defect structure of both the sapphire substrate and the silicon film, including integral and local (at the atomic-resolution level) information about the substrate, film, and sapphire-silicon interface.

Modification of the Langmuir–Schaefer method for fabrication of ordered protein films

A modification of the Langmuir–Schaefer method for the fabrication of high-quality protein films on a solid substrate was proposed and applied to lysozyme. The procedure relies on the use of a pre-prepared protein solution, the parameters of which correspond to crystallization conditions. A lysozyme Langmuir monolayer was shown to be formed with the involvement of complexes, namely, dimers and octamers of protein molecules that are present in such protein solutions. These complexes apparently retain the structure after spreading a protein solution onto an aqueous subphase in a Langmuir trough. The thickness of the film after the transfer of the monolayer, which was formed by the proposed procedure, onto a solid substrate corresponds to the diameter of the octamer and this film is dense, continuous, and uniform, as was demonstrated by several methods: X-ray reflectivity, total external reflection X-ray standing wave, and atomic force microscopy. A layer of chloride ions that formed under the Langmuir monolayer was found at the air–protein film interface. This fact confirms an important role of the precipitating agent (chloride ions) in all steps of the formation of lysozyme films.

Integument structure in ornithischian dinosaurs (Hypsilophodontia, Ornithopoda) from the Late Jurassic of Transbaikalia

Integumentary structures of ornithischain dinosaurs of the taxon Hypsilophodontia (Ornithopoda) from the Ukureiskaya Formation (Upper Jurassic) of the Kulinda locality (Transbaikal Region, Russia) are described in detail. It is shown that members of this group had so-called bristle scales, integumentary appendages previously unknown in ornithischian dinosaurs. These are relatively small horn plates embedded in the skin, the distal margin of which has several long, flat, and probably constantly growing bristles. The monobristle variant of bristle scale is probably homologous to the protofeather of theropods; if this is the case, it is possible to reconstruct the protofeather as an elongated and constantly growing scale.

Comparison of the data of X-ray microtomography and fluorescence analysis in the study of bone-tissue structure

The possibility of localizing clusters of heavy atoms is substantiated by comparing the data of X-ray microtomography at different wavelengths, scanning electron microscopy, and X-ray fluorescence analysis. The proximal tail vertebrae of Turner’s thick-toed gecko (Chondrodactylus turneri) have been investigated for the first time by both histological and physical methods, including X-ray microtomography at different wavelengths and elemental analysis. This complex methodology of study made it possible to reveal the regions of accumulation of heavy elements in the aforementioned bones of Turner’s thick-toed gecko.

Investigation of the thermal diffusion during the formation of a quasicrystalline phase in thin Al-Pd-Re films

The layer mixing during the formation of the Al70Pd20Re10 icosahedral quasicrystalline phase in thin (55 nm) Al-Pd-Re layered film systems subjected to vacuum annealing has been studied. It is shown that a combined layer of Pd and Al atoms (with the Al3Pd2 phase dominating) is formed in the first stage (at 350°C), while the rhenium layer remains invariable. In the second annealing stage (at 450°C), the β′-AlPd phase is formed and the Re layer is diffused. In the third stage (700°C), Pd and Re atoms are uniformly distributed throughout the film with the formation of a quasicrystalline phase.

X-ray analysis of multilayer In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As HEMT heterostructures with InAs nanoinsert in quantum well

In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As HEMT heterostructures on InP substrates with elastically strained InAs insert in combined quantum well (QW) have been investigated using a combination of X-ray methods: double-crystal X-ray diffraction, X-ray reflectivity, and reciprocal space mapping. This approach has provided detailed complementary information about the layered and real crystal structures of the samples. The data obtained have made it possible to perform structural analysis of the multilayer systems and compare their characteristics with specified technological parameters, due to which the HEMT growth technology can be corrected and improved.

Thermal stability of organic layered systems based on lead stearate

The structural variation in multilayer Langmuir-Blodgett films of lead stearate caused by heat treatment under different conditions in the temperature range 20–100°C is investigated by X-ray reflectometry and high-resolution electron diffraction. Successive annealing of the samples is shown to not alter the initial layered structure at temperatures of 60, 80, and 100°C; partial disturbance of the layered structure occurs upon successive annealing at 80°C and 100°C. Significant disturbance of the structure is observed when the films are heated immediately to 100°C. In all these cases, the orthorhombic (pseudomonoclinic) lattice, with the lattice constants: a = 0.496, b = 0.738, c = 9.60 nm, α = β = γ = 90°, space group P2/1b, formed by transferring monolayers onto the substrate is retained in the crystalline domains of the film.

An Automatic Control System of the Synchrotron Station and Special Features of the Experiment Automation at the LANGMUIR Station of the Synchrotron Radiation Source of the RRC Kurchatov Institute

A universal software-hardware architecture of the automatic control system (ACS) of the X-ray experiment for synchrotron stations is designed. The designed ACS ensures the reliable long-time control of the station equipment from remote terminals located in safety zones. A hierarchical three-level architecture of the control system based on personal industrial computers and specialized microcontrollers is selected to realize the hardware part. Data channels are based on Ethernet, RS-485, and RS-232 interfaces. The ACS software embodies the functional-modular principle and contains monitor modules with parametric adjustment, group control modules of functional station blocks, and modules for individual control of mechanisms. Data exchange between the modules is supported by TCP/IP, DCON, and other standard communication protocols. When the control system was being designed, the possibility of expanding the system by embedding bought articles from leading manufacturers was without fail taken into account. The designed system allows its integration with automated experiment control systems. The work presents details of the designed ACS realization on the LANGMUIR multipurpose research technological system of the synchrotron radiation source of the Russian Research Centre (RRC) Kurchatov Institute, the Russian synchrotron station intended for studying interfaces of various nature by using a wide spectrum of precision surface-sensitive and spectrum-selective X-ray technologies, in particular, for studying organic and bioorganic nanosystems on liquid surfaces and various planar nanostructures on solid substrates. The specific character of the LANGMUIR station invited development of a unique software-hardware module for controlling optical elements deflecting the beam from the horizontal line (beam control module), and creation of a special software unit for integrating the fluorescence signal recording section into the ACS and synchronization of the X-ray and fluorescence sections.