Dietmar Kopp
The deposition of different low friction multi-component systems by the Atmospheric Pressure Plasma Deposition (APPD) technique on engineering thermoplastics will be investigated. In terms of low friction coating, MoS2 represents a well-known as well as an established benchmark material in diverse industrial applications on the market. A large variety of unfilled thermoplastics such as polyamides (PAs) are technically easy to process and do not require high temperature processes. However, uncoated PAs exhibit a relatively low wear resistance and high coefficient of friction (COF) values in contact with another counterpart and their field of applications is significantly limited over a wide temperature range. State of the art techniques such as PVD have been already developed for DLC or composite surfaces. However, those coatings tend to be only feasible for generating a very thin coating thickness in the range of <5 µm. In addition, the applied coating can easily crack, abrasive wear particles arise, and the low friction properties transform into the opposite (e.g. delamination phenomenon). An alternative to PVD for producing thicker layers >20 µm is APPD and higher deposition rates under ambient conditions instead of a cost intensive vacuum chamber. Finally, the plasma-process-structure relationship of the multi-component coating system based on the atmospheric plasma spraying process, especially understanding the impact from the plasma and the atmospherically occurring conditions will be investigated as benchmark for the commercial market.
Anna Werkovits
The arrangement of organic molecules at organic-metal interfaces is a key factor determining their electronic, mechanical, and other functional properties. The range of the system’s properties depends on the polymorphs accessible during growth. For conjugated organic molecules, that have more than one functional group with a strong affinity to the substrate, the accessible polymorphs of the wetting layer are typically in a flat-lying orientation. But as reported for, e.g., TCNE/Cu(111), HATCN/Ag(111), and NO2-Pyt/Ag(111), the first layer can reorient from flat-lying to an upright-standing phase upon deposition of additional molecules. For the examples mentioned, the phase transition is accompanied by a change in the interface work function of at least 1 eV. Although such coverage-dependent reorientations are only occasionally documented, theoretical considerations lead us to expect them to be more common from a thermodynamic standpoint.
To test this hypothesis, we studied TCNE/Cu(111) to reveal how kinetic factors drive the deviation from thermodynamic expectations focusing on the relationship between coverage, molecular orientation, and phase stability. First, we explore the kinetic pathways of individual molecules and find that for deposition rates typical in physical vapor deposition experiments, ordered lying structures are expected to be kinetically trapped between 110 and 160 K. Furthermore, we gain experimental insights from our collaborators via X-ray photoelectron and infrared reflection absorption spectroscopy, as well as from our advanced microkinetic growth simulations that include sorption processes and steric effects. Under realistic growth conditions, simulation suggests that the reorientation is primarily constrained by the availability of additional molecules for adsorption. Moreover, trapping of lying structures occurs in the simulations for realistic deposition rates even up to room temperature. These findings are corroborated at 200 K in the experiment. In turn, there is an indication of the existence of mixed phases at room temperature, which suggests that the real system is more complex than our approximated theoretical models. To create expectations of how plausible the kinetic trapping of lying structures is for other systems, we vary the parameters of the energy landscape in our microkinetic simulations. Increasing reorientation and diffusion barriers do not qualitatively impact our findings, whereas for lying molecules that are weaker bound to the substrate kinetic trapping is reduced.
Alexander Eber
The combination of short acquisition times, high spectral resolution, and an inherently broad bandwidth makes dual-comb spectroscopy (DCS) an ideal tool for field sensing in the planetary boundary layer. Due to these advantages and the ready availability of laser sources, DCS has become a standard technique for field sensing in the infrared spectral region. Here, a dual-comb spectrometer is implemented in the visible spectral region for field sensing. A compact, mobile dual-comb setup was developed, tested, and successfully implemented, allowing measurements at different locations and different beam geometries.
We employ different laser systems with different parameters, alter beam geometries, and sender/receiver and reflector set-ups for the measurements and compare them to further optimize the experiments.
Lukas Fürst
Ultraviolet (UV) dual-comb spectroscopy (DCS) has been realized by several research groups most recently. The advantages of broad spectral coverage, fast acquisition time, and high spectral resolution enable the detailed investigation of the electronic energy structure of matter as well as the rovibronic properties of all molecular species. Among these, species like formaldehyde (HCHO) and nitrogen dioxide (NO2) are particularly interesting due to their interaction with solar UV photons in the atmosphere. To perform sensitive and specific atmospheric monitoring and modelling of photochemical processes induced by solar UV light, high-resolution absolute absorption cross section spectra are required. So far, the near-ultraviolet absorption cross section of formaldehyde has not been extensively studied, indicating the need for further investigation.
In this talk, the first broadband dual-comb spectrometer in the UV spectral region will be presented. It enables to investigate three major vibronic branches of HCHO and to track changes of the HCHO concentration suitable for environmental monitoring. Furthermore, results of a free-running DCS system with high spectral resolution are presented. The setup empowers to test fundamental constants, determining the absorption cross section of new absorption lines in HCHO and to detect perturbations of quantum mechanical systems.
Johannes Krondorfer: Optical nuclear electric resonance - selective adressing of nuclear spins through pulsed laser excitation
Matthias Diez: Molecular magnetism induced by rotational and vibrarional motion
Siegfried Kaidisch: Momentum-space signatures of charge-transfer excitations in donor-acceptor dimers from GW/BSE calculations
Georg Grassler: Parameter study of neoclassical toroidal viscous torque for 3D coils in EU-DEMO
Philipp Christ: Advanced Nanoscale Characterization of Organic Photovoltaic Materials
Anmol Androta: Symmetry Breaking and Chirality: A Journey through molecular Crystals
Verena Reisecker: Advanced Plasmonic Nanostructures: FEBID as a Tool for Free-Standing Designs
Anton Nrecaj
Driven by active materials research, there are constantly new introductions of innovative materials. This results in higher requirements for, e.g., the instrumentation for thermomechanical analysis (TMA), considering all the different materials ranging from metals to polymers. The aim is therefore the development of highly accurate and reliable devices, which are capable of measuring a broad range of materials and geometric shapes to fully capture all thermo- mechanical events occurring in the material. This trend of measuring increasingly small changes under different conditions justifies this research work for an adapted thermomechanical measuring cell with a focus on the investigation on new materials.
Hybrid drives consist of a coarse and a fine stage, actuated simultaneously and controlled by the same positioning system. While other configurations for thermomechanical analyzers exist, they generally have to cope with drawbacks like limited displacement range or the need for a complex cooling system on moving parts. This present work introduces a high-precision hybrid drive capable for TMA with long travel ranges that are only restricted by the length of the linear guide and eliminating the need for a complex cooling system and the need for manual operations for different initial sample sizes. The setup consists of a combination of a fine positioning element, e.g., a piezo stage, and a coarse positioning element, e.g., a motor spindle. Both actuators are controlled by a loadcell, with a resolution of less than 1 mN, which passes a signal to both actuators to ensure simultaneous operation to keep the force constant during the expansion or shrinkage of the sample. The length measurement is performed by a frictionless optical encoder with a resolution smaller than 2 nm after interpolation.
First, different suitable systems are evaluated for the required functions for TMA. Thereafter, different concepts have been derived suitable to perform the desired task. Then, the performance is demonstrated first with a piezo walking leg simulation drive as a sample simulator, providing the required expansion rates. Finally, a measurement on a CuZn39Pb3 sample, that exhibits an additional length change effect, associated with the melting of lead inside the brass matrix upon heating, has been carried out to demonstrate the feasibility of the approach. The presented high-precision hybrid drive TMA significantly extends the measurement range and reduces the complexity of the design.
Anas Alatrash
The scientific questions to be addressed in QualiTool focus on the role and interaction of the binder material in cemented carbides. The CVD diamond coating of cemented carbide tools leads to complex changes in the microstructure. These changes affect the tool cutting edges depending on the parameters of the cemented carbide production and/or the parameters applied during the grinding of the tools. Thus, this change in the material’s microstructure properties influences the process limits of the machining. The goal of increasing the performance of CVD-diamond coated can only be achieved if the microstructure of these tool’s cutting edges can be specifically influenced. This requires fundamental investigations of the microstructural changes through the entire process chain (sintering, grinding, etching, coating). First TEM investigations carried out at ZFE Graz proved the existence of microcrystalline areas in the cobalt before coating in the case of industrially produced cemented carbide. Through our investigations, these changes can be predicted by the magnetic saturation (MS) of the sample. Furthermore, EBSD analyses proved that proportions of hexagonal and face-centred cubic cobalt phases change depending on the MS value; this is directly related to the proportion of elements dissolved in the cobalt and on the allotropic transformations of the binder induced in the grinding process (grinding-induced phase transformations). All in all, this hinders the ability to obtain an optimal diamond layer.
Lukas Seewald
While miniaturization in semiconductor industry has reached levels causing debates about the end of Moore’s law, reaching ever smaller dimensions is an ongoing trend in many fields of science driving the development of microscopy at such scales. Amongst electron and fluorescence microscopy, atomic force microscopy (AFM) is a high-resolution technique able to access the nanoscale. AFM is applicable in different atmospheres and operating conditions ranging from liquid environments to ultra-high vacuum. In addition to topography images with lateral resolution in the nanoscale, advanced operation modes in conjunction with functionalized probes enable access to material’s and surface properties, e.g. thermal, magnetic, electronic, optical etc. at the same or similar resolution. The common approach to probe functionalization via coating of standard probes with functional materials reduces achievable resolution by increasing the probe apex. Moreover, the coating can be worn off or delaminate rendering such probe inoperable. An approach to circumvent both problems are probes fabricated entirely from a functional material. Amongst few other techniques, 3D Nanoprinting via Focused Electron Beam Induced Deposition (FEBID) is very well suited to fabricate fully functional probes with apex radii below 10 nm [1], demonstrated by recent publications. [2,3,4]
An ongoing research is the design and integration of probes with multiple combined functionalities to access several materials properties, potentially even within a single scan. Such probes could drastically improve correlative microscopy avoiding the requirement to change probes between different operation modes. Along suitable materials properties the integration on a fitting microelectromechanical cantilever is equally important, governing operational stability and probe wear. This talk will encompass an introduction to FEBID based 3D Nanoprinting and AFM with an emphasis on fabrication of advanced AFM nanoprobes. Based on this introduction, the development of a nanoprobe combining magnetic and conductive properties is discussed, comprising probe functionality and integration on a suitable cantilever. Images of different samples and spectroscopic data highlight both the magnetic and the conductive properties of these probes and thereby underline the applicability of FEBID based 3D Nanoprinting towards fabrication of advanced AFM nanoprobes.
[1] H. Plank et al. Focused Electron Beam-Based 3D Nanoprinting for Scanning Probe Microscopy: A Review, Micromachines 11(1), 48 (2020)
[2] M. Jaafar et al. Customized MFM probes based on magnetic nanorods, Nanoscale 12, (2020) 10090
[3] J. Sattelkow & L.M. Seewald et al., 3D Nanoprinting of All-Metal Nanoprobes for Electric AFM Modes, Nanomaterials 12(24), (2022) 4477
[4] R. Winkler & M. Brugger-Hatzl et al., Additive Manufacturing of Co3Fe Nano-Probes for Magnetic Force Microscopy