SEKCE E - POKROČILÉ METODY PŘÍPRAVY A CHARAKTERIZACE NANOSYSTÉMŮ

The international length metrology community has identified the need for novel standards for length metrology that are not based on lithographically produced artefacts calibrated using optical microscopy or devices fitted with optical interferometers. When the International System of Units (the SI) was updated in 2018, the lattice parameter of silicon was adopted as a secondary standard of length for dimensional nanometrology. Its use is described in the Mise en Pratique for the metre [1] - the formal document from the International Bureau of Weights and Measures that describes how the SI unit of length should be realized in practice. The talk will cover the three prescribed methods using the silicon lattice for length metrology: monoatomic height standards for calibration of atomic force microscopes (AFMs) together with the processing of associated AFM data [2]; counting atoms in transmission electron microscope images to measure the linewidth structures used in semiconductor metrology [3]; and X-ray interferometry for sub-nanometre nanopositioning and error measurement in displacement sensors [4].
The last decade has seen a growth high-speed AFMs, however, many applications have been without metrology. In some cases, the high-speed of the scanning stage is at the expense of motion accuracy affecting both the image quality and the ability to extract reliable quantitative data from the image. The talk will show how metrology can be applied to high speed-AFM to make it a quantitative technique [5], how quantitative large area images can be obtained without the need for image stitching, and how errors in stage motion can be measured and their effect removed from measurement data [6].
REFERENCES: [1] https://www.bipm.org/en/publications/mises-en-pratique/ accessed August 2026; [2] Garnaes J et al. 2020 Algorithms for using silicon steps for scanning probe microscope evaluation Metrologia 57 064002; [3] Dai G et al. 2017 Comparison of line width calibration using critical dimension atomic force microscopes between PTB and NIST Meas. Sci. Technol. 28 065010; [4] Pisani M, et al. 2012 Comparison of the performance of the next generation of optical interferometers, Metrologia 49 455-467; [5] Heaps E et al. 2020 Bringing real-time traceability to high-speed atomic force microscopy Meas. Sci. Technol. 31 074005 (11pp); [6] Heaps E et al. 2025 Large area high-speed atomic force microscopy with arbitrary scan path playback Meas. Sci. Technol. 36 066213 (8pp).

Two-dimensional materials exhibit unique surface, electrical, and mechanical properties, making them promising candidates for nanoscale coatings and functional interfaces. However, establishing a direct relationship between atomic-scale chemical modifications and local mechanical interactions remains a challenge for graphene oxide (GO)-based systems.
In this work, atomic force microscopy (AFM) was employed to investigate the influence of controlled thermal reduction of single-layer graphene oxide flakes on their nanoscale properties. Thermal treatment up to 150 °C, associated with the removal of oxygen-containing functional groups, resulted in a decrease in GO flake thickness and an increase in nanoscale electrical conductivity measured by conductive AFM.
AFM force spectroscopy revealed the dependence of tip-GO adhesion on the applied normal load. For pristine GO, increasing the applied load resulted in enhanced adhesion, which is attributed to an increase in the real contact area, allowing more oxygen-containing surface functional groups to interact with the AFM tip . With increasing reduction degree, the adhesion force dependence on the applied load reaches a plateau, indicating a stabilization of the tip-GO contact area.
Friction force microscopy measurements demonstrated velocity-dependent friction behavior with several distinct regimes associated with different nanoscale dissipation mechanisms. Molecular dynamics simulations complemented experimental results by extending the accessible sliding velocity range and providing atomistic insight into friction mechanisms, including stick-slip behavior at the AFM tip-GO interface.
The combination of AFM-based characterization and molecular dynamics simulations establishes a direct correlation between chemical modification of graphene oxide, nanoscale surface interactions, and friction mechanisms, highlighting AFM as a powerful approach for understanding the functional properties of two-dimensional materials.
ACKNOWLEDGEMENTS: This work was supported by the National Science Centre in Poland under Project No. 2020/37/B/ST8/02023.
REFERENCES: [1] Weiss, M., Majchrzycki, Ł., Borkowska, E., Cichomski, M., Ptak, A. (2021), Tribology International, 162, 107133; [2] Weiss, M., Majchrzycki, Ł., Skonieczny, R., Florjan, D., Ptak, A. (2025), Tribology International, 201, 110203.

The relevance of ultrathin films and 2D materials in modern devices is continuously increasing, prompting a growing interest in the chemical analysis of these multilayer systems and their surfaces. A thorough characterization of stoichiometries, composition, and depth distribution of elements is crucial. The novel EnviroMETROS series revolutionizes the field of surface hybrid metrology and serves as an ideal tool for routine analysis in this research and development field. It is a unique metrology platform for the chemical analysis of ultrathin films and 2D materials that allows for a detailed characterization of stoichiometries‚ composition and depth distribution of elements. In combination with optical and other analytical techniques it enables depth dependent composition analysis of unsurpassed precision‚ reliability and repeatability.
The new EnviroMETROS series consists of fully automated XPS/HAXPES metrology systems consequently designed for depth dependent chemical analysis of samples, utilizing multi-wavelength X-ray excitations and parallel angle detection (PARXPS). Furthermore, it can work in variable atmospheres from UHV to NAP-conditions. The (NAP)-XPS/ HAXPES analysis is accompanied by several measurement techniques on the same spot, like UPS/IPES/REELS for electronic structure studies, small spot XPS and SEM/SAM for chemical mapping correlated to morphology, LEISS for ultimate surface sensitivity, Raman as well as IRRAS as optical methods for structural information. It can be used for large samples (EnviroMETROS LAB) as well as wafer handling (EnviroMETROS FAB).
The presentation will highlight the details of the EnviroMETROS series, as an ideal tool for routine analysis of ultrathin films and 2D materials for modern devices and give an insight into the large field of applications.

Aluminum Nitride (AlN) is a critical material for nanodevices, next-generation electronics and particularly optoelectronics, where AlN-based piezoelectric microelectromechanical systems (MEMS) mirrors provide the rapid, low-power beam steering essential for modern LiDAR applications. However, device efficiency is heavily influenced by nanoscale defect interactions. Our work utilizes molecular statics and dynamics simulations to investigate the structural properties of the AlN epitaxial layer on a Si substrate, applying an innovative empirical model that consistently describes covalent bonding. A primary focus is the analysis of the complex interfaces between AlN and silicon substrates, which is essential for integrating these nanostructured semiconductors with existing technologies and optimizing epitaxial growth.
Accurately simulating these interfaces requires highly reliable interatomic potentials. To this end, we have developed a robust Tersoff-style potential for the Al-N-Si subsystem, parameterized using Density Functional Theory (DFT) calculations. We validate this potential on the silicon (111) surface, encompassing 1x1, 2x1, √3x√3 and 7x7 reconstructions. To investigate early-stage nanomaterial epitaxy, we initially simulate the deposition of a single Aluminum atom, evaluating surface placement and substitutional doping, before modeling a complete Al layer to observe its effect on surface reconstruction. Because epitaxial growth typically follows an alternating deposition pattern initiated by Aluminum, therefore, understanding this initial substrate-adatom interaction is critical for minimizing dislocation densities and enhancing device efficiency. Furthermore, we benchmark our potential against established models, specifically the Jelinek (2012) MEAM and Starikov (2020) ADP potentials, to evaluate its comparative accuracy in capturing nanoscale interfacial behavior.

The selective semihydrogenation of alkynes to alkenes is an important transformation for the production of fine chemicals and polymer intermediates yet achieving high activity while suppressing over-hydrogenation remains a persistent challenge. Single-atom catalysts (SACs) provide an attractive platform for addressing this limitation because their isolated metal centers offer well-defined coordination environments and tunable electronic structures. In this work, we discuss how electronic structure modulation at single-atomic sites can be used to control the adsorption and activation of alkynes and hydrogen while steering the reaction toward the desired alkene products. In particular, heteroatom coordination and metal-support interactions provide an effective means of tuning the electronic structure of the active centers and promoting selective hydrogenation pathways while suppressing excessive hydrogenation of the resulting alkene. The isolated nature of the active sites further limits ensembles responsible for consecutive hydrogenation, providing an additional strategy for improving alkene selectivity. Combining catalyst synthesis, advanced structural characterization, catalytic evaluation, and theoretical calculations, we establish relationships between the local electronic structure of single-atomic sites and their catalytic behavior. This work demonstrates that rational electronic and spatial engineering of isolated metal centers can provide a promising route toward efficient and highly selective semihydrogenation of alkynes, while offering opportunities to reduce the reliance on conventional noble-metal nanoparticle catalysts.

Cardiovascular diseases remain a leading cause of mortality worldwide, and vascular grafts are widely used for the treatment of damaged or occluded blood vessels. However, thrombosis at the graft surface remains a major clinical challenge, particularly for small-diameter vascular grafts, thereby limiting their long-term success. Therefore, the development of innovative graft materials with improved hemocompatibility is needed. In this study, bicomponent fibrous surfaces composed of polycaprolactone (PCL) and polyvinyl alcohol (PVA) were fabricated for small-diameter vascular graft applications, combining the mechanical strength of PCL with the hydrophilic, drug-carrying capacity of PVA, and heparin was loaded into the fibers to provide antithrombotic activity and prevent clot formation on the graft surface. Neat and heparin-loaded PCL/PVA surfaces exhibited uniform fibers with diameters within the range of 1.3-1.5 µm, and heparin loading did not have a significant effect on surface morphology. Moreover, pore diameter and porosity were evaluated, with porosity exceeding 75% for all samples, supporting cell infiltration. Contact angle measurements revealed a hydrophobic character predominantly reflecting the properties of PCL, regardless of heparin incorporation. Cytocompatibility was assessed by seeding human umbilical vein endothelial cells (HUVECs) on the fibrous surfaces and monitoring viability via the MTS assay on days 3, 7, and 14. An increase in viability was observed across all surfaces, indicating that the fabricated PCL/PVA bicomponent fibers support cellular activity from day 3 to day 14. These findings suggest that heparin-loaded PCL/PVA bicomponent fibrous surfaces possess favorable morphological and biological properties for small-diameter vascular graft applications.

Positron annihilation spectroscopy (PAS) is a nondestructive technique used to characterize open volume defects in solids, such as vacancies, vacancy clusters, dislocations, and grain boundaries. Delocalized positrons probe the interstitial sites of the crystalline lattice. When a material contains open volume defects, positrons can be trapped there, allowing them to examine the local electron density and chemical environment of these defects. There are two key observables related to the positron annihilation process: the positron lifetime in the sample and the Doppler shift in the energy of annihilation gamma rays. Positron lifetime spectroscopy can identify the types and concentrations of defects present in a sample, while coincidence Doppler broadening provides information about the local chemical environment of those defects.
Hydrogen absorbed in solids occupies interstitial sites within the crystalline lattice, which are the same regions analyzed by delocalized positrons. Additionally, hydrogen is attracted to open volume defects and tends to segregate at the inner surfaces of these defects. Not only does hydrogen bind to existing open volume defects in the material, but its absorption also introduces new defects. The interaction between hydrogen and various defects, along with the defects created by hydrogen, can significantly impact physical properties of materials. This phenomenon can be thoroughly investigated using PAS, and it will be illustrated in the talk.

Understanding the physical mechanisms governing dry friction at the nanoscale is essential for improving the reliability of micro- and nanoelectromechanical systems and for developing strategies to control friction and wear. Although numerous studies have demonstrated the influence of sliding velocity, normal load, and temperature on friction, a consistent physical interpretation of these dependencies remains challenging.
In this work, we present a unified physical interpretation of dry nanoscale friction based on quantitative atomic force microscopy experiments and nonequilibrium molecular dynamics simulations. Friction measured over broad ranges of sliding velocity, normal load, and temperature is analysed using the Prandtl-Tomlinson and Dudko-Hummer-Szabo models for thermally activated processes.
Our results show that sliding velocity, normal load, and temperature shift the operating point on the interaction potential between the contacting surfaces, thereby changing the dominant energy dissipation mechanism. As a consequence, the system undergoes transitions between stick-slip-, smooth-sliding-, and adhesive-friction-dominated regimes. Rebinding effects additionally influence the friction force, particularly at low loads and low sliding velocities. Experimental friction data can be represented using a unified velocity-to-load parameter, revealing a characteristic friction minimum associated with these transitions. Molecular dynamics simulations reproduce the experimentally observed behavior and provide atomistic insight into the underlying mechanisms.
The proposed framework establishes a consistent physical basis for understanding and predicting dry nanoscale friction by linking operating conditions to the interaction potential and the resulting energy dissipation mechanisms. It also provides practical guidelines for tailoring operating conditions to minimize friction and wear.

High-entropy materials, particularly oxides, have attracted significant attention recently due to their multicomponent composition enabling broad control over electronic structure, surface properties, and defect chemistry, including mixed-valence centres and oxygen vacancies that influence charge generation, accumulation, transfer, and the functional properties. In this work, a combined Rietveld structure refinement (RSR) and the Maximum Entropy Method (MEM) was used as a helpful tool to gain insight into the crystal and electronic structures and electron-density distribution of a type of these materials from X-ray powder diffraction data. Mg(Mn0.2Cr0.2Co0.2Fe0.2Ni0.2)2O4 has been used as a model high-entropy spinel oxide (HEO) for the investigation. The HEO was initially synthesised using the co-precipitation method, followed by analysis through X-ray diffraction (XRD), and subsequently refined using RSR. The results from the theoretical RSR calculations and the experimental XRD data were nearly identical. The phase was accurately identified, and a structural model was established, characterised by a cubic form with the space group Fd3m and lattice parameters of A = 8.40 Å. The atomic positions, cation-site occupancies, oxygen positional parameter, and unit-cell volume were also provided. The MEM electron-density map constructed reveals electron-density accumulation between the metal cations and oxygen anions, suggesting partial covalent character in the metal-oxygen bonds. The diffuse electron-density distribution observed on the crystallographic planes indicates substantial disorder at the spinel B-sites. Rietveld-MEM combined analysis has proven to be a suitable tool for providing a detailed representation of the material's structure and offers insight into the relationship between its structural disorder and functional properties.

Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) is a scanning probe approach to optical microscopy and spectroscopy bypassing the ubiquitous diffraction limit of light to achieve a spatial resolution below 10 nanometer. New possibilities emerging with new correlative system attocube Ira-SCOPE, which allows comprehensive spectroscopic material analysis and chemical identification with micro- to nanometer resolution by seam¬lessly merging modern Laser-Direct Infrared (LDIR) reflection absorption spectroscopy, state-of-the-art confocal Raman micro-spectroscopy, and high-sensitivity nano-IR technologies such as nano-FTIR and AFM-IR imaging & spectroscopy. Combining these micro and nano mapping options in one instrument will be described via examples from microbiology, polymer, graphene transistor and Metal Organic Framework (MOF) research.

Conventional Voronoi tessellation methods often produce overly idealized grain boundaries in atomistic simulations of nanocrystalline materials, artificially inflating mechanical properties and leading to discrepancies with experimental measurements. To address this, we introduce a cylindrical sintering method to construct nanocrystalline aluminum thin-film samples with wider, more disordered grain boundaries than conventional Voronoi models, while preserving deterministic control over grain size, shape, and orientation. Molecular dynamics simulations using the Modified Embedded-Atom Method (MEAM) potential developed by Pascuet et al. (2015) show that the cylindrical sintered samples consistently exhibit lower mechanical properties than conventional hexagonal Voronoi structures owing to their heightened structural disorder at the boundaries. Common neighbor analysis and dislocation extraction analysis confirm that deformation is dominated by grain-boundary-mediated plasticity. Consequently, both sample types exhibit an inverse Hall-Petch relationship under uniaxial tension, where overall mechanical strength decreases with reducing grain size. Overall, this cylindrical sintering approach offers a physically realistic, geometrically controlled framework that bridges the gap between idealized Voronoi models and complex experimental microstructures.

Optical properties were measured using photocurrent and frequency resolved photoluminescence spectroscopy (f-resolved PL). In our previous papers [Z. Remeš et al, J. Phys. Conf. Ser. 2712 (2024) 012004, Z. Remeš et al, J. Phys. Conf. Ser. 2931 (2024) 012011, and Z. Remeš et al, Phys._Scr. 100 (2025) 115910] we presented an upgrade of our spectrofluorometer optimize to measure the phase shift between sinusoidal UV excitation and PL emission at low temperature (4 K) using lock-in amplifier. Here we apply this method to evaluate the mean PL decay time of Co-doped ZnO thin films grown by pulsed lased deposition (PLD). The work was supported by the Czech Science Foundation projects 24-10607J and by Operational Programm Jan Amos Komensky (OP JAK) financed by ESIF and the MEYS (Project No. LASCIMAT - CZ.02.01.01/00/23_020/0008525).

Electron microscopy is evolving beyond conventional imaging, opening new possibilities for high-resolution observation, precise manipulation and advanced analytical characterization. This presentation will introduce selected new technologies that push the capabilities of modern electron microscopy in these directions.
A particular focus will be placed on CIQTEK electron microscopy and its SuperTunnel electron optics column technology, designed to enable high-resolution imaging at low accelerating voltages. The second part will introduce Imina nanorobotic solutions for precise manipulation, probing and positioning at the micro- and nanoscale, enabling manipulation and in-situ experiments across different microscopy and characterization techniques.
The final part will focus on the latest developments in Bruker analytical detectors, including the new XFlash 7200 FIRE four-segment EDS detector with unique 200 mm2 active area, XFlash FlatQUAD 2Lcombining highly efficient EDS with simultaneous BSE imaging, and the eWARP TKD detector for fast, high-resolution nanoscale crystallographic characterization.
Together, these technologies demonstrate how modern microscopy is moving beyond simply seeing a sample towards correlated imaging, manipulation and analytical insight.

Heterogeneous catalysis plays an indispensable tool in modern industrial processes. When supported nanoparticles are downsized to the single-atom limit, the resulting single-atom catalysts (SACs) have proven special value1. These individually dispersed metal sites possess defined coordination structures and enabled reaction pathways that differ from traditional heterogeneous catalysis. While offering high stability even in harsh environments, and maximum utilization of catalytic metals, SACs also satisfy the key goals of a sustainable chemistry. Nevertheless, limited reproducibility and scalability of SAC preparation hinder their further practical applications, and efficient methods of SAC synthesis are urgently needed. A major challenge is to prepare single-atom sites on the catalyst support with high density while avoiding aggregation of metal atoms. This challenge can be traced to the trade-off between diffusion and stabilization of metal atoms during the pyrolysis process. In this talk, several approaches will be presented2,3. These methods will discuss how the metal resources including ions, organometallic complexes, and particles are transformed into single atoms and their possible mechanisms. This work is a critical step forward toward a scalable synthesis and widespread application of dense SACs and pavs the way for the development of further economically feasible catalyst systems

Random-bit generation is essential for numerical simulations, statistical sampling, optimization, and cryptography. In this work, we compare binary sequences produced by a classical pseudorandom-number generator and a present-day quantum-computer processor. We place a particular emphasis on small samples in which an approximately equal proportion of the two possible measurement outputs (zeros and ones) is desirable. We aim at solid-state physics applications where random displacement of atoms are important for computing materials properties of crystals, such as phonons. In particular, considering positive and negative random displacements of atoms in the computational cell, we generated the random data by both classical pseudorandom-number generator and IBM quantum computer. These data are divided into small blocks and evaluated using the mean and variance of the fraction of ones, bit-string frequencies, Shannon entropy, inter-qubit correlations, temporal autocorrelation, chi-square tests, and the Fano factor. Preliminary results suggest that, under certain conditions, quantum-hardware outputs may exhibit smaller fluctuations in the block-wise fraction of zeros and ones than classical pseudorandom sequences. Such sub-binomial behavior may originate from hardware noise, readout errors, or correlations between qubits and successive measurements. Although reduced variance does not imply higher randomness or better cryptographic quality, it may be advantageous in applications requiring balanced small binary samples, such as displacement of atoms in solid-state physics calculations.

Metal-organic polyhedra (MOPs) represent a unique class of discrete, zero-dimensional porous materials that serve as molecular cages for constructing hierarchical porous architectures. Unlike extended frameworks, MOPs offer tunable solubility, rich surface chemistries, and modular functionalities, making them highly versatile for applications in gas storage and separation, catalysis, and energy harvesting. However, their broader utilization has been limited by challenges such as moisture sensitivity, inadequate mechanical stability, and the presence of complex, often inaccessible pore structures. To address these limitations, strategies have been explored to enhance hydrolytic stability, including the incorporation of hydrophobic functional groups and integration with polymer matrices.
Our group has advanced this field by designing MOP-based materials with improved robustness and functionality through both covalent and coordinative functionalization. These modifications are achieved either by introducing pre-functionalized linkers during synthesis or via post-synthetic modifications, enabling fine-tuned control over MOP surface chemistry. Such tailored MOPs have been successfully employed in heterogeneous catalysis, electrochemical CO₂ reduction reactions (CO₂RR), energy storage, and triboelectric nanogenerator-based energy harvesting. This talk will highlight our recent progress in engineering MOPs as multifunctional platforms, emphasizing how structural design and surface chemistry together drive stability, reactivity, and application potential in sustainable energy and environmental technologies.
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