X-ray Reflectivity Research Articles

Misfit Layered Compounds: Insights into Chemical, Kinetic, and Thermodynamic Stability of Nanophases.

ConspectusCompounds with layered structures (2D-materials), like transition metal-dichalcogenides (e.g., MoS2), attracted a great deal of interest in the scientific community in recent years. This interest can be attributed to their unique lamellar structure, which induces large anisotropy in their physicochemical properties. Furthermore, owing to the weak van der Waals interaction between the layers, they can be cleaved along the a-b plane, which allows fabricating single layers with physical properties entirely different from the bulk material. Moreover, stacking layers of different 2D-materials on top of each other has led to a wealth of new observations, for instance, by twisting two layers with respect to each other and producing Moiré lattice. Another outstanding property of inorganic layer compounds is their tendency to form nanotubes, reported first (for WS2) many years ago and subsequently from many other layered compounds.Among the 2D-materials, misfit layer compounds make a special class with an incommensurate and nonstoichiometric lattice made of an alternating layer with rocksalt structure, like LaS (O) and a layer with hexagonal structure, like TaS2 (T). The lack of lattice commensuration between the two slabs leads to a built-in strain, which can be relaxed via bending. Consequently, nanotubes have been produced from numerous MLC compounds over the past decade and their structure was elucidated.Owing to their large surface area, nanostructures are generally metastable and tend to recrystallize into microscopic crystallites via different mechanisms, like Ostwald ripening, or chemically decompose and then recrystallize. The stability of nanostructures at elevated temperatures has been investigated quite scarcely so far. In this perspective, electron microscopy as well as synchrotron-based X-ray absorption and reflection techniques were used to elucidate the chemical selectivity and decomposition routes of rare-earth based MLC nanotubes prepared at elevated temperatures (800-1200 °C).As for the chemical selectivity, entropic effects are expected to dictate the random distribution of the chalcogen atoms on the anion sites of the MLC nanotubes at elevated temperatures. Nonetheless, the sulfur atoms were found to bind exclusively to the rare-earth atom (Ln = La, Sm) of the rocksalt slab and the selenium to the tantalum of the hexagonal TX2 slab. This uncommon selectivity was not found in other kinds of nanotubes like WSe2xS2(1-x). In other series of experiments, the lack of utter symmetry in the multiwall nanotubes leads to exclusions of certain X-ray (0kl) reflections, which was used to distinguish them from the bulk crystallites. The transformation of Ln-based MLC nanotubes into microscopic flakes was followed as a function of the synthesis temperature (800-1200 °C) and the synthesis time (1-96 h). Furthermore, sequential high-temperature transformations of the (O-T) lattice into (O-T-T) and finally (O-T-T-T) phases via deintercalation of the LnS slab was observed. This autocatalytic process is reminiscent of the deintercalation of alkali atoms from different layered structure materials. Annealing at higher temperatures and for longer periods of time eventually leads to the decomposition of the ternary MLC into binary metal-sulfide phases, as well as partial oxidation of the product. This study sheds light on the complex mechanism of high-temperature chemical stability of the nanostructures.

Novel method for quantifying the ratios of sp3/sp2 hybridized carbon in diamond-like carbon films using soft X-ray emission spectroscopy

This study presents a pioneering method for quantifying the ratios of sp3/sp2 hybridized carbon in diamond-like carbon (DLC) films. The novelty lies in using soft X-ray emission spectroscopy (SXES), a technique not widely employed in this context. The DLC films, obtained through various deposition methods, were characterized for hydrogen content, film density, and sp3/sp2 ratio using Rutherford backscattering spectroscopy/Elastic recoil detection analysis (RBS/ERDA), X-ray reflectivity (XRR), and SXES, respectively. To ensure the reliability of the SXES method, it was validated through comparative analysis with near-edge X-ray absorption fine Structure (NEXAFS) spectroscopy, providing confidence in its accuracy. While NEXAFS provided consistent sp3/sp2 ratio measurements in hydrogen-free DLC films, its accuracy in hydrogenated DLC films was impacted due to poor accuracy when applied to this film group. In contrast, SXES demonstrated greater precision in hydrogenated and hydrogen-free DLC films, revealing sp3/sp2 ratios ranging from 36 % to 62 %, corresponding variations in hydrogen contents and film densities. These findings highlight the superior utilization of SXES in accurately determining the sp3- and sp2-hybridized carbon ratios, particularly in hydrogenated DLC films, offering a robust alternative to NEXAFS and paving the way for enhanced characterization and application in various industrial fields.

Multi-epoch UV–X-Ray Spectral Study of NGC 4151 with AstroSat

We present a multiwavelength spectral study of NGC 4151 based on five epochs of simultaneous AstroSat observations in the near-ultraviolet (NUV) to hard X-ray band (∼0.005–80 keV) during 2017–2018. We derived the intrinsic accretion disk continuum after correcting for internal and Galactic extinction, contributions from broad- and narrow-line regions, and emission from the host galaxy. We found a bluer continuum at brighter UV flux, possibly due to variations in the accretion disk continuum or the UV reddening. We estimated the intrinsic reddening, E(B − V) ∼ 0.4, using high-resolution Hubble Space Telescope (HST)/STIS spectrum acquired in 2000 March. We used thermal Comptonization, neutral and ionized absorption, and X-ray reflection to model the X-ray spectra. We obtained the X-ray absorbing neutral column varying between N H ∼1.2 and 3.4 × 1023 cm−2, which are ∼100 times larger than that estimated from UV extinction, assuming the Galactic dust-to-gas ratio. To reconcile this discrepancy, we propose two plausible configurations of the obscurer: (a) a two-zone obscurer consisting of dust-free and dusty regions, divided by the sublimation radius, or (b) a two-phase obscurer consisting of clumpy, dense clouds embedded in a low-density medium, resulting in a scenario where a few dense clouds obscure the compact X-ray source substantially, while the bulk of UV emission arising from the extended accretion disk passes through the low-density medium. Furthermore, we find a positive correlation between the X-ray absorption column and NUV − far-UV color and UV flux, indicative of enhanced winds possibly driven by the “bluer-when-brighter” UV continuum.

Artificial synapses based on HfOx/TiOy memristor devices for neuromorphic applications

As a result of enormous progress in nanoscale electronics, interest in artificial intelligence (AI) supported systems has also increased greatly. These systems are typically designed to process computationally intensive data. Parallel processing neural network architectures are particularly noteworthy for their ability to process dense data at high speeds, making them suitable candidates for AI algorithms. Due to their ability to combine processing and memory functions in a single device, memristors offer a significant advantage over other electronic platforms in terms of area scaling efficiency and energy savings. In this study, single-layer and bilayer metal-oxide HfOxand TiOymemristor devices inspired by biological synapses were fabricated by pulsed laser and magnetron sputtering deposition techniques in high vacuum with different oxide thicknesses. The structural and electrical properties of the fabricated devices were analysed using x-ray reflectivity, x-ray photoelectron spectroscopy, and standard two-probe electrical characterization measurements. The stoichiometry and degree of oxidation of the elements in the oxide material for each thin film were determined. Moreover, the switching characteristics of the metal oxide upper layer in bilayer devices indicated its potential as a selective layer for synapse. The devices successfully maintained the previous conductivity values, and the conductivity increased after each pulse and reached its maximum value. Furthermore, the study successfully observed synaptic behaviours with long-term potentiation, long-term depression (LTD), paired-pulse facilitation, and spike-timing-dependent plasticity, showcasing potential of the devices for neuromorphic computing applications.

Epitaxial growth of GaN on β-Ga2O3 via RF plasma nitridation

The lack of suitable p-type dopant for β-Ga2O3 remains a hurdle for vertical power device applications. Epitaxy of GaN on Ga2O3 substrates was demonstrated as an alternative. (–201)-oriented β-Ga2O3 was converted into (0001)-oriented hexagonal GaN via nitrogen plasma in a plasma-assisted molecular beam epitaxy chamber, as verified by XRD and RHEED. The resulting nitridated GaN layers were characterized by TEM, x-ray reflectivity, and AFM to relate the nitridation conditions to crystallinity, layer thickness, and surface roughness. The crystallinity of subsequently grown epitaxial GaN films was quantified via XRD rocking curves and related to the nitridation layer properties across varying nitridation conditions. Specifically, the effect of the grain size and nitridation layer thickness was investigated to determine their role in threading screw dislocation management.

Investigating Gold Deposition with High-Power Impulse Magnetron Sputtering and Direct-Current Magnetron Sputtering on Polystyrene, Poly-4-vinylpyridine, and Polystyrene Sulfonic Acid.

Fabricating thin metal layers and particularly observing their formation process in situ is of fundamental interest to tailor the quality of such a layer on polymers for organic electronics. In particular, the process of high power impulse magnetron sputtering (HiPIMS) for establishing thin metal layers has sparsely been explored in situ. Hence, in this study, we investigate the growth of thin gold (Au) layers with HiPIMS and compare their growth with thin Au layers prepared by conventional direct current magnetron sputtering (dcMS). Au was chosen because it is an inert noble metal and has a high scattering length density. This allows us to track the growing nanostructures via grazing incidence scattering. In particular, Au deposition on the polymer polystyrene (PS) with the respective structural analogues poly-4-vinlypyridine (P4VP) and polystyrene sulfonic acid (PSS) is studied. Additionally, the nanostructured layers on these different polymer films are further probed by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray reflectometry (XRR), and four-point probe measurements. We report that HiPIMS leads to smaller island-to-island distances throughout the whole sputter process. Moreover, an increased cluster density and an earlier percolation threshold are achieved compared to dcMS. Additionally, in the early stage, we observe a significant increase in coverage by HiPIMS, which is favorable for the improvement of the polymer-metal interface.

New insights into the Devonian sea spiders of the Hunsrück Slate (Arthropoda: Pycnogonida).

The sea spiders (Pycnogonida Latreille, 1810) of the Hunsrück Slate (Lower Devonian, ~400 million years ago) are iconic in their abundance, exquisite pyritic preservation, and in their distinctive body plan compared to extant sea spiders (Pantopoda Gerstäcker, 1863). Consequently, the Hunsrück sea spiders are important in understanding the deep evolutionary history of Pycnogonida, yet they remain poorly characterised, impacting upon attempts to establish a time-calibrated phylogeny of sea spiders. Here, we investigated previously described and new material representing four of the five Hunsrück pycnogonids: Flagellopantopus blocki Poschmann & Dunlop, 2006; Palaeoisopus problematicus Broili, 1928; Palaeopantopus maucheri Broili, 1929; and Pentapantopus vogteli Kühl, Poschmann & Rust, 2013; as well as a few unidentified specimens. Using X-ray microtomography and Reflectance Transformation Imaging, we describe new fossils, provide evidence for newly revealed anatomical features, and interpret these data in comparison to extant species. We also reinterpret the previously published illustration of the (probably lost) holotype of Palaeothea devonica Bergström, Stürmer & Winter, 1980. We provide the first detailed description of the cephalic appendages of Palaeoisopus problematicus and revise the interpretation of the organisation of its ocular tubercle. Furthermore, we provide new insights into the structure of the legs and the proboscis of Palaeopantopus maucheri, the first description of the body of Flagellopantopus blocki and describe a new specimen of Pentapantopus vogteli, demonstrating that it had eight legs, in contrast to previous interpretations. We argue that, contrary to previous suggestions, Palaeothea devonica probably had a different body plan from extant pantopods. We discuss the ecological traits of the Hunsrück pycnogonids based on their morphological adaptations, and conclude that there is no compelling evidence of Pantopoda in the Devonian. Through comparative interpretation of the legs as well as general morphology, we can divide the Hunsrück pycnogonids into two morphological groups, while Pantopoda constitutes a third morphological group.

Impact of plasma power on plasma enhanced atomic layer deposited TiO2 as a spacer

As the size of devices is scaled down, micro-patterning technology is increasing in importance. In micro-patterning, spacers require precise thickness and uniform deposition at low temperature. To meet these requirements, atomic layer deposition (ALD), which can be controlled to an accurate thickness, was introduced. Therefore, we investigated plasma-enhanced ALD using radicals for high reactivity. Optical emission spectroscopy and a Langmuir probe were used to evaluate plasma properties such as radical intensity and plasma density at different plasma powers. Regardless of plasma power, growth per cycle and compositions of Ti and O remained constant. X-ray photoelectron spectroscopy showed that application of 500 W decreased the area of Ti2O3 from 20.2 % to 4.5 % compared with 100 W due to the increased amount of oxygen radicals. X-ray reflectivity results showed a 4.09 g/cm3 density of TiO2 film at 100 W, which increased to 4.2 g/cm3 at 500 W, indicating a decrease of Ti2O3. Meanwhile, the wet etch rate of TiO2 film was 1.72 Å/min at 100 W and 0.8 Å/min at 500 W, and the denser film had superior etch resistance. Finally, transmission electron microscopy showed that step coverage of TiO2 films improved from 90.9 % to 99.9 % with increasing power. Thus, application of high power effectively improved the properties of TiO2 films.

Structural and Spectroscopic Characterization of Supported Sarcoplasmic Reticulum Membranes on Solid Substrates.

Sarcoplasmic reticulum (SR) membranes from rabbit muscle were deposited on silicon substrates and characterized by the combination of spectral ellipsometry (SE), high energy specular X-ray reflectivity (XRR), specular neutron reflectivity (NR), and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Following the optimization of the preparative conditions by SE, the detailed structures in the direction perpendicular to the membrane were probed by XRR. ATR-FTIR data showed strong signals from amide I and amide II bands of the native SR membranes containing a large amount of Ca2+-ATPase, which could not be achieved by the reconstitution in artificial lipid membranes. The treatment with protease led to a significant decrease in the amide peaks, and the XRR data confirmed the modulation of the membrane structures. The obtained data show the potential of the in situ combination of reflectivity and vibrational spectroscopy of native supported membranes in order to unravel both structure and dynamics of complex biological membranes.

Optical anisotropy and surface phases of cholesterol derivative monolayer at air–water interface

Cholesterol and its derivatives play crucial roles in regulating processes of biological membranes. Langmuir monolayer can mimic a bio-membrane which can be used to investigate the molecular interaction governing the important physical phenomena. The cholesterol derivative exhibiting mesophases (CHLC molecules) was synthesized and spread at the air–water (A/W) interface to investigate the surface behavior. The monolayer exhibited a variety of surface phases such as gas, liquid expanded (LE), low density liquid like (L1) and liquid condensed (L2) phases. Treating the CHLC molecules to be rod-like, the average tilt of the molecules with respect to the surface normal in these phases are found to be different. The tilt angle decreases systematically from LE to L2 phase. The optical anisotropy of the ultrathin Langmuir-Blodgett (LB) films of CHLC molecules in these phases was measured using the surface plasmon resonance (SPR) spectroscopy. The high tilted molecules in the ultrathin LB film displayed a high value of optical anisotropy. The ultrathin film of CHLC molecules at different interfaces was investigated using Brewster angle microscopy, X-ray reflectivity (XRR), SPR spectroscopy and atomic force microscopy. This study is useful for the systems where the physical phenomena are governed by tilt of the molecules.

Increased neutron reflectivity and polarization of neutron-optical engineered Fe/B411CTi multilayer optics

The concept of scattering length density tuning for improved polarization is investigated for Fe/B411CTi multilayers and compared to the commonly used Fe/Si system in polarizing multilayer neutron optics. X-ray and neutron reflectivity, magnetization, and neutron polarization were measured on such multilayers, highlighting differences from conventional Fe/Si multilayers. The multilayer systems were deposited with 25 Å period thickness, a layer thickness ratio of 0.35, and 20 periods using ion-assisted dc magnetron sputtering. Replacing Si with B411CTi for these multilayers showed an increase in reflectivity due to a reduction in interface width. Tuning the ratio between B411C and Ti in the nonmagnetic layers enabled a wide range of scattering length density contrasting and matching for spin-down neutrons, which in turn led to an improved polarization. These findings demonstrate the potential of Fe/B411CTi multilayers as a promising option for polarizing neutron optics and highlight the concept of scattering length density tuning in a large range using B411CTi. Published by the American Physical Society 2024

INFLUENCE OF THE RATIO OF GASE CONSUMPTION N<sub>2</sub>/Ar AND MAGNETRON POWER ON THE DENSITY AND STOICHIOMETRIC COMPOSITION OF TIN<sub>X</sub> FILMS SYNTHESIZED BY MAGNETRON SPUTTERING METHOD

The films of titanium nitride were deposited by direct current magnetron sputtering on the surface of singlecrystalline silicon samples in an Ar-N2 atmosphere for use as a diffusion barrier. The thickness and density of films were measured by X-ray reflectometry. The design of the MAGNA TM-200-01 installation has been changed to increase the supply of nitrogen into the chamber. The influences of sputtering conditions, including the flow rate of nitrogen and argon gases and their N2 /Ar ratios in the range of 1–60 in the chamber, magnetron power of 690–1400 W on the formation of TiNx films, their density and stoichiometric composition, were studied. It is shown that the value of x is affected not only by the N2 /Ar gas flow rate ratio, but also by the magnetron power. At the sputtering parameters 1200 W, N2 /Ar = 30, 0.8 Pa, 320 s and 100°C, a maximum density of 5.247 g/cm3 of a film was achieved, which corresponds to the composition TiN0.786 = Ti56N44. The presence of nanocrystalline film of titanium nitride and the absence of a nanocrystalline titanium phase were confirmed by photographic X-ray diffraction. It was found that for the synthesis of titanium nitride as close as possible to the stoichiometric composition TiN0.770 - TiN0.786, it is necessary to use magnetron power in the range of 900–1200 W, nitrogen rate of 30 cm3 /min with low argon flows of 1–5 cm3 /min.

Investigating the consistency of the shape and flux of X-ray reflection spectra in the hard state with an accretion disk reaching close to the black hole

The observed spectra from black hole (BH) X-ray binaries (XRBs) typically consist of two primary components. A multitemperature blackbody originating from the accretion disk in the soft X-ray, and a power law-like component in the hard X-ray, due to the Comptonization of soft photons by the hot corona. The illumination of the disk by the corona gives rise to another key component known as reflection. A fraction of the incident hard X-ray radiation is naturally absorbed and re-emitted as a blackbody at lower energies and referred to as the ``reprocessed blackbody''. For densities relevant to XRBs and typical ionization values, the reprocessed blackbody may become significant in the soft X-ray region (approximately 0.1-1.0 keV) and should be noticeable in the observed spectra as a consequence of reflection. The absence of any blackbody component in the low/hard state of a BH XRB may not be consistent with the reflection of highly irradiating flux, observed as a power law from an appropriately dense disk of XRB. We focus on the low/hard state of the BH XRB MAXI J1820+070. In contrast to previous works, we simultaneously fit the shape and flux of the reflection spectra. This allowed us to estimate the correct density and ionization of the slab as well as the corresponding reprocessed blackbody. Our fitting of the representative observation of the BH XRB low/hard state suggests that the disk may, in principle, extend very close to the BH, even though the reprocessed thermal emission (due to disk illumination) remains cold (and thus low) enough to be consistent with the data in contrast to the results of a previous study. The inner reflection component is highly ionized and its fit is primarily driven by its contribution to the continuum, rather than by the shape of the relativistic iron line. The reprocessed blackbody cannot help determine whether the disk extends close to the BH or not in the hard state. For this specific observation, the flux in inner reflection component turns out to be quite low with respect to the outer reflection or power law. The outflowing slab corona covering the inner region of the disk could be the plausible geometry of the source, with the underlying disk approaching near to the BH.

Improving the Lithography Sensitivity of Atomically Precise Tin‐Oxo Nanoclusters via Heterometal Strategy

Tin‐oxo clusters are increasingly recognized as promising materials for nanolithography technology due to their unique properties, yet their structural impacts on lithography performance remain underexplored. This work explores the structural impacts of heterometal strategies on the performance of tin‐oxo clusters in nanolithography, focusing on various metal dopants and their coordination geometries. Specifically, SnOC‐1(In), SnOC‐1(Al), SnOC‐1(Fe), and SnOC‐2 were synthesized and characterized. These clusters demonstrate excellent solubility, dispersibility, and stability, facilitating the preparation of high‐quality films via spin‐coating for lithographic applications. Notably, this work innovatively employs nano‐infrared (nano‐IR), neutron reflectivity (NR), and X‐ray reflectivity (XRR) measurements to confirm film homogeneity. Upon electron beam lithography (EBL), all four materials achieve 50 nm line patterns, with SnOC‐1(In) demonstrating the highest lithography sensitivity. This enhanced sensitivity is attributed to indium dopants, which possess superior EUV absorption capabilities and unsaturated coordination environments. Further studies on exposure mechanisms indicated that Sn–C bond cleavage generates butyl free radicals, promoting network formations that induce solubility‐switching behaviors for lithography. These findings underscore the efficacy of tailored structural design and modulation of cluster materials through heterometal strategies in enhancing lithography performance, offering valuable insights for future material design and applications.

Improving the Lithography Sensitivity of Atomically Precise Tin-Oxo Nanoclusters via Heterometal Strategy.

Tin-oxo clusters are increasingly recognized as promising materials for nanolithography technology due to their unique properties, yet their structural impacts on lithography performance remain underexplored. This work explores the structural impacts of heterometal strategies on the performance of tin-oxo clusters in nanolithography, focusing on various metal dopants and their coordination geometries. Specifically, SnOC-1(In), SnOC-1(Al), SnOC-1(Fe), and SnOC-2 were synthesized and characterized. These clusters demonstrate excellent solubility, dispersibility, and stability, facilitating the preparation of high-quality films via spin-coating for lithographic applications. Notably, this work innovatively employs nano-infrared (nano-IR), neutron reflectivity (NR), and X-ray reflectivity (XRR) measurements to confirm film homogeneity. Upon electron beam lithography (EBL), all four materials achieve 50 nm line patterns, with SnOC-1(In) demonstrating the highest lithography sensitivity. This enhanced sensitivity is attributed to indium dopants, which possess superior EUV absorption capabilities and unsaturated coordination environments. Further studies on exposure mechanisms indicated that Sn-C bond cleavage generates butyl free radicals, promoting network formations that induce solubility-switching behaviors for lithography. These findings underscore the efficacy of tailored structural design and modulation of cluster materials through heterometal strategies in enhancing lithography performance, offering valuable insights for future material design and applications.

Influence of nitrogen and niobium incorporation in bcc-chromium coatings on microstructure and mechanical properties

Stoichiometric CrN and Cr:N with different nitrogen (N) content are of interest for hard coating applications. In the Cr-N material system, bcc-Cr rich coatings, containing a few percent of diluted N, provide tunability in microstructure and mechanical properties. Additionally, the incorporation of Nb into the CrNx coatings may further tailor the materials properties. In this work, bcc-CrNx and CrNbNx coatings were deposited by reactive magnetron sputtering, and their mechanical and microstructural characteristics were investigated as a function of N content. Depending on the N content, the phases observed by X-ray diffractometry (XRD) varied from metallic bcc-Cr, mixed bcc-Cr/h-Cr2N, to h-Cr2N/CrN. X-ray reflectivity (XRR), and scanning electron microscopy (SEM) measurements show that a dense and nearly columnar-free bcc-CrNx coatings was obtained at ~13–25 at.% of N, while CrNbNx coatings composed of dense, column-free, and featureless microstructure at a N content of ~10–20 at.%. The dense and nearly column-free microstructure composed of dispersion of Cr2N grains into the bcc-Cr matrix for both CrNx and CrNbNx coatings, as shown by high resolution transmission electron microscope analysis (HRTEM). Nanoindentation revealed a hardening of the coatings due to the grain refinement, solid solution strengthening, and variation in phase content.

Next-generation Accretion Disk Reflection Model: High-density Plasma Effects

Luminous accretion disks around black holes are expected to have densities of ∼1015−1022 cm−3, which are high enough that plasma physics effects become important. Many of these effects have been traditionally neglected in the calculation of atomic parameters, and therefore in photoionization models and ultimately also in X-ray reflection models. In this paper, we describe updates to the atomic rates used by the xstar code, which is in turn part of the xillver disk reflection model. We discuss the effect of adding necessary high-density corrections into the xillver code. Specifically, we find that the change of recombination rates plays an important role, dominating the differences between model versions. With synthetic spectra, we show that, even in a highly ionized state, high-density slabs can produce strong iron (∼6.5–9 keV) and oxygen (∼0.6–0.8 keV) resonance features. The significant iron emission could address the problem of the supersolar iron abundances found in some sources.

Selective regulation of macrophage lipid metabolism via nanomaterials’ surface chemistry

Understanding the interface between nanomaterials and lipoproteins is crucial for gaining insights into their impact on lipoprotein structure and lipid metabolism. Here, we use graphene oxide (GOs) nanosheets as a controlled carbon nanomaterial model to study how surface properties influence lipoprotein corona formation and show that GOs have strong binding affinity with low-density lipoprotein (LDL). We use advanced techniques including X-ray reflectivity, circular dichroism, and molecular simulations to explore the interfacial interactions between GOs and LDL. Specifically, hydrophobic GOs preferentially associate with LDL’s lipid components, whereas hydrophilic GOs tend to bind with apolipoproteins. Furthermore, these GOs distinctly modulate a variety of lipid metabolism pathways, including LDL recognition, uptake, hydrolysis, efflux, and lipid droplet formation. This study underscores the importance of structure analysis at the nano-biomolecule interface, emphasizing how nanomaterials’ surface properties critically influence cellular lipid metabolism. These insights will inspire the design and application of future biocompatible nanomaterials and nanomedicines.

Complex Diagnostics of Silicon-on-Insulator Layers after Ion Implantation and Annealing

A technology was developed for activating ion-implanted dopants in silicon-on-insulator layers at a low annealing temperature (600°C) using the pre-amorphization technique of a silicon device layer. In the case of phosphorus implantation, silicon was amorphized directly by dopant ions. In the case of boron implantation for pre-amorphization, the layers were preliminary irradiated with argon or fluorine ions. Complex diagnostics of the implanted layers was carried out using secondary ion mass spectrometry, X-ray diffractometry and small-angle X-ray reflectometry. The combination of methods made it possible to characterize the impurity distribution, the degree of silicon crystallinity, the layer thicknesses, and the interface widths in structures. The results of diagnostics of the structure and composition correlate well with calculations in the SRIM software package and the electrophysical characteristics of the layers after annealing. It was shown that the use of argon for pre-amorphization of silicon interfered with the recrystallization process and did not make it possible to achieve acceptable electrical characteristics of the doped layer. Amorphization with phosphorus and pre-amorphization with fluorine during boron implantation allowed obtaining the required values of the resistance of the doped layers after annealing at a temperature of 600°C. The use of a complex approach made it possible to optimize the modes of amorphization, ion doping, and annealing of silicon-on-insulator structures at low temperatures, necessary for the creation of light-emitting device structures based on silicon-germanium nanoislands.

On the Multi-Layered Adsorption of Alcanols in the Vicinity of Liquid–Vapor Transition at the Saturated Hydrocarbon–Water Interface

Structure of adsorption layer of long-chain monoatomic alcohols: 1-dodecanol and 1-tetracosanol at the interfaces n-hexane – water and n-hexadecane – water in the vicinity of “liquid – vapor” thermotropic phase transition is investigated by the method of X-ray reflectometry at synchrotron source. Model-independent structural data obtained on the adsorption layers under investigation deviate considerably from the structural parameters which have been proposed previously within a model-based representation and discussed in previous publications on said systems. It is shown that in the low-temperature mesophase the adsorption film consists of a Gibbs monolayer, a transitional liquid region with thickness of two to three monolayers ~50 Å and an extended (wide up to 200 Å) layer of micelles. Presence of a plane of the closest approach of micellar layer to the adsorption film at the interface is established. Transition to the high-temperature mesophase is followed by liquefying and partial evaporation of alcanol film along with observed depletion of micellar layer down to its complete disappearance.