TY - JOUR A1 - Schmitt, Paul A1 - Felde, Nadja A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Uschmann, Ingo A1 - Hanemann, Kevin A1 - Siegler, Marie A1 - Klemm, Georg A1 - Gratzke, Nancy A1 - Tünnermann, Andreas A1 - Schwinde, Stefan A1 - Schröder, Sven A1 - Szeghalmi, Adriana T1 - Optical, structural, and functional properties of highly reflective and stable iridium mirror coatings for infrared applications JF - Optical Materials Express N2 - Metallic coatings are essential for numerous optical systems due to their high and broadband refl ectivity in the infrared spectral range. In contrast to well-established (protected)silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally,the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI,AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings diff er due to their topography and microstructure. KW - Iridium KW - mirror KW - Sputter KW - ALD KW - Iridium KW - Beschichtung Y1 - 2022 U6 - https://doi.org/10.1364/OME.447306 VL - 2022 IS - 12 / 2 SP - 545 EP - 559 ER - TY - JOUR A1 - Schmitt, Paul A1 - Felde, Nadja A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Uschmann, Ingo A1 - Hanemann, Kevin A1 - Siegler, Marie A1 - Klemm, Georg A1 - Gratzke, Nancy A1 - Tünnermann, Andreas A1 - Schwinde, Stefan A1 - Schröder, Sven A1 - Szeghalmi, Adriana T1 - Optical, structural, and functional properties of highly reflective and stable iridium mirrorcoatings for infrared applications: supplement JF - Optical Materials Express N2 - Metallic coatings are essential for numerous optical systems due to their high and broadband refl ectivity in the infrared spectral range. In contrast to well-established (protected)silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally,the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI, AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings diff er due to their topography and microstructure. KW - Iridium KW - mirror KW - ALD KW - Sputter KW - Iridium KW - Beschichtung Y1 - 2022 U6 - https://doi.org/10.6084/m9.figshare.17121509 VL - 2022 IS - 12/2 SP - 545 EP - 559 ER - TY - CHAP A1 - Döhring, Thorsten A1 - Stieglitz, Veronika A1 - Hudec, Rene A1 - Sapsai, Iryna A1 - Friedrich, Peter A1 - Burwitz, Vadim T1 - Characterization of a lobster-eye type X-ray telescope T2 - EPJ Web of Conferences N2 - Lobster-eye type X-ray telescopes use reflecting plano mirrors under grazing incidence and can observe a large field of view. As part of a Bavarian-Czech cooperation, two telescopes were build, equipped with mirrors coated with gold and iridium. Their X-ray characterization was carried out at the PANTER test facility, which simulates parallel starlight incident on the telescopes. The telescopes have an angular resolution of about 4 arc minutes in X-rays and a focal length of about 2 meters. The used X-ray mirrors reflect and focus visible light as well; their functionality in the optical regime was checked in laboratory tests. Now another test campaign will be carried out to examine the telescope resolution for real objects of the visible night sky and the imaging properties for star constellations. KW - X-ray telescopes KW - Lobster-eye KW - Grazing incidence KW - Large field of view KW - Röntgenteleskop KW - Röntgenspiegel Y1 - 2022 UR - https://doi.org/10.1051/epjconf/202226613010 U6 - https://doi.org/10.1051/epjconf/202226613010 VL - 266 (2022) SP - 1 EP - 2 ER - TY - JOUR A1 - Stieglitz, Veronika A1 - Burwitz, Vadim A1 - Döhring, Thorsten A1 - Hudec, Rene A1 - Vitek, Stanislav T1 - Design and testing of a Kirkpatrick-Baez optics variation JF - EPJ Web of Conferences N2 - Beside Wolter I X-ray optics, which are used at most in currently operating X-ray space telescopes, there exist also other optical designs and their usability for space observations is still the matter of studies. This article covers preliminary testing results of an optical module which is based on a modified Kirkpatrick-Baez optics. This X-ray optics, consisting of four sub-modules, was assembled in Prague and tested at the PANTER test facility of MPE afterward. The sub-modules use different reflective coatings, in part developed by our research group, on complementary flat mirrors, which approximate the shape of a Kirkpatrick-Baez optical design. In this contribution we summarise the design of the optical modules, the details of applied coating layers, and the X-ray characterisation results at the PANTER test facility KW - Kirkpatrick-Baez optics KW - X-ray telescopes KW - Reflective coatings KW - Röntgenoptik KW - Spiegelteleskop Y1 - 2022 UR - https://www.epj-conferences.org/articles/epjconf/abs/2022/10/epjconf_eosam2022_03021/epjconf_eosam2022_03021.html U6 - https://doi.org/10.1051/epjconf/202226603021 VL - 266 (2022) SP - 1 EP - 2 ER - TY - CHAP A1 - Mann, Michael A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Priebsch, Alessandro A1 - Pribulla, Theodor A1 - Komžík, Richard M. A1 - Sivanic, Peter ED - Storrie-Lombardi, Lisa J. ED - Benn, Chris R. ED - Chrysostomou, Antonio T1 - Advanced power quality measurement techniques at the electric power grid of astronomical observatories T2 - Observatory Operations: Strategies, Processes, and Systems X, Conference of SPIE 13098, 17 - 20 June 2024 KW - Sternwarte KW - Elektrizitätsversorgung Y1 - 2024 U6 - https://doi.org/10.1117/12.3016562 PB - SPIE ER - TY - CHAP A1 - Ermilova, Elena A1 - Hertwig, Andreas A1 - Döhring, Thorsten A1 - Stanik, Eva A1 - Cotroneo, Vincenzo A1 - Gibertini, Eugenio T1 - Ellipsometrische Charakterisierung von Polydopamin für funktionelle technische Schichten T2 - DGaO-Proceedings N2 - Dünne Schichten aus dem bionischen Material Polydopamin (PDA) sind heute zunehmend auch für innovative technische Anwendungen von Interesse. Mittels spektroskopischer Ellipsometrie wurde die dielektrische Funktion von PDA vom ultravioletten bis zum nahen infraroten Spektralbereich vermessen. Über ein Modell wurde auch die Dicke dieser selbstorganisierenden Schichten bestimmt. KW - Polydopamin KW - PDA KW - Ellipsometrie KW - Röntgenspiegeln KW - Astronomie KW - Dünne Schicht KW - Röntgenastronomie Y1 - 2024 UR - https://www.dgao-proceedings.de/download/125/125_b6.pdf VL - 2024 IS - 125 SP - 1 EP - 2 ER - TY - JOUR A1 - Amorim, Isilda A1 - Spera, Natalia C.M. A1 - Nicoara, Nicoleta A1 - Ramasamy, Devaraj A1 - Alves, Diana F. A1 - Stollenwerk, Manfred A1 - Stadtmüller, Johannes A1 - Döhring, Thorsten A1 - Sadewasser, Sascha A1 - Kolen'ko, Yury V. A1 - Sousa, Juliana P.S. T1 - Overall alkaline water electrolysis over active, stable, low loading iridium catalysts sputtered on nickel foam JF - International Journal of Hydrogen Energy KW - Iridium KW - Katalysator KW - Wasserstoffelektrolyse KW - Wasser KW - Elektrolyse KW - Wasserstofferzeugung Y1 - 2024 U6 - https://doi.org/10.1016/j.ijhydene.2024.10.306 SN - 0360-3199 VL - 92 SP - 852 EP - 864 PB - Elsevier BV ER - TY - GEN A1 - Stanik, Eva A1 - Döhring, Thorsten A1 - Zeising, Sebastian A1 - Meißner, Martin T1 - An astronomy event at Aschaffenburg University to attract future engineering students T2 - 18th INTEGRAL/BART Workshop N2 - In 2023 the German Federal Ministry of Education and Research (BMBF) and the German organization for science communication “Wissenschaft im Dialog” (German for: Science in dialogue) jointly proclaimed a "Science Year" with the motto “Our Universe”. One of the numerous events that have been supported thereby has been that of the project "Zirkus UNI-versum" (in English: "Circus UNI-verse"), which took place in summer 2023 at Aschaffenburg University of Applied Sciences. Two school classes from the local high school “Kronberg-Gymnasium” first experienced an interactive astronomy lecture including a planetarium star show in a tent. Another highlight was the rocket car race in front of the cafeteria and the exclusive launch of a water rocket on the campus green. After the collective countdown, it reached a height of around eighty meters and thus rose higher than all the trees and buildings on the campus site. For their own exploration of the night sky the pupils obtained small cardboard star maps to assemble themselves as a homework. On the summer evenings of the following school holidays, they certainly observed the sky with a different point of view and, above all, with expert knowledge. The event has given them interesting impressions of Aschaffenburg Technical University as an attractive local education facility. The project "Zirkus UNI-versum" – and other activities for schools – intend to stimulate the interest of pupils in STEM subjects and to attract future engineering students. N2 - Poster KW - astronomy event KW - MINT KW - engineering students KW - STEM KW - Astronomie KW - Vorlesung Y1 - 2024 VL - 2024 SP - 1 EP - 1 ER - TY - CHAP A1 - Stanik, Eva A1 - Döhring, Thorsten A1 - Pregler, Jan A1 - Kätker, Anna A1 - Busch, Uwe A1 - Friedrich, Peter T1 - A visitor experiment on astronomical X-ray optics for the "Deutsches Röntgen-Museum" T2 - AXRO 2024 - 15th International Conference on Astronomical X-Ray Optics N2 - The “Deutsches Röntgenmuseum” in Remscheid is the unique institution worldwide that researches and documents the life and work of the first Nobel Prize winner, Wilhelm Conrad Röntgen, and the effects of his discovery of X-rays. As an integral part of the museum, the RöLab laboratory offers visitors the opportunity to gain practical experience in X-rays, optics and technology through own experiments. As part of a joint development project, students from Aschaffenburg University of Applied Sciences are currently designing a visitor experiment on astronomical X-ray optics for the museum laboratory. An optical set-up with visible light illustrate the focusing principle of X-ray telescopes, e.g. for wide-angle optics based on the lobster-eye principle. Display boards explain the optics of various types of telescopes with accompanying text and corresponding illustrations. Modern X-ray observatories such as CHANDRA, XMM-Newton and eROSITA are presented clearly. Once implemented, the new visitor experiment inside the “Deutsches Röntgenmuseum” intend to inspire young researchers for the fascinating world of X-ray optics and X-ray astronomy. KW - X-ray astronomy KW - X-ray optics KW - X-ray telescope KW - Deutsches Röntgen-Museum KW - Deutsches Röntgen-Museum KW - Röntgen, Wilhelm Conrad, 1845-1923 KW - Röntgenstrahlung Y1 - 2024 VL - 2024 SP - 1 EP - 1 ER - TY - CHAP A1 - Wissel, Julian A1 - Freudenmann, Dominic A1 - Perez, Nicolas A1 - Döhring, Thorsten A1 - Stadtmüller, Johannes A1 - Stollenwerk, Manfred T1 - Various highly effective sputtered layer structures as catalysts for H2O2 decomposition for use in satellite engines T2 - MaterialsWeek 2025 – Book of Abstracts N2 - Catalysts are frequently employed in both research and industrial applications to facilitate or accelerate chemical reactions. One such application is in monopropellant thrusters for space propulsion systems, where hydrogen peroxide (H2O2) is used as a liquid propellant. The decomposition of liquid hydrogen peroxide into water and oxygen gas, which ultimately generates thrust, can be achieved using noble metal catalysts from the platinoid group, such as platinum and iridium. This promotes the use of more environmentally friendly and less toxic propellants, such as H2O2, instead of hydrazine and nitrogen tetroxide (NTO). The optimization of coating structures with these catalytic materials is essential for future space applications, as it aims to extend the lifespan of catalyst materials and results in a better utilization of H2O2 in satellite engines. Therefore, different layer structures were deposited onto Duranit D99 pellets using a controlled magnetron sputtering process. Previous studies have shown that the used sputtering pressure has a strong influence on the structure of the deposited coatings [2][3]. Certain parameter combinations produce catalytic layers with rough textures and a highly porous microstructure, see figure 1 [1]. To improve the thermal and mechanical stability of the sputtered layers, thin adhesive layers of Titanium and Zirconium were applied beneath the catalytic layer. The pellets were then heated in an oven at 640°C for one minute to simulate the thermal effects experienced in a satellite engine during ignition. Following this, the catalytic performance of the pellets was tested in laboratory experiments using 30% H2O2. Pellets with sputtered platinum as the catalytic coating delivered the best results. These coatings will be further evaluated in an engine test conducted at the German Aerospace Centre (DLR). Hydrogen peroxide is also expected to play a crucial role in future lunar and Martian colonization efforts. In this context, catalytic coatings would be used to decompose H2O2 to supply astronauts with water and oxygen, rather than to generate thrust in satellite engines. KW - catalyst KW - satellite propulsion KW - sputtered layers KW - iridium KW - platinum KW - Satellitentechnik KW - Katalysator Y1 - 2025 SN - 978-3-88355-446-4 SP - 53 EP - 53 PB - Deutsche Gesellschaft für Materialkunde e.V. (DGM) CY - Sankt Augustin ER - TY - CHAP A1 - Cotroneo, Vincenzo A1 - Bruni, Ricardo A1 - Civitani, Marta Maria A1 - Döhring, Thorsten A1 - Gibertini, Eugenio A1 - Magagnin, Luca A1 - Pareschi, Giovanni A1 - Rivolta, Giacomo A1 - Romaine, Suzanne A1 - Sethares, Leandra A1 - Sironi, Giorgia A1 - Tagliaferri, Gianpiero A1 - Valsecchi, Giuseppe T1 - Dopamine dip-liquid overcoatings for soft X-ray reflectivity enhancement T2 - Proceedings of SPIE N2 - It has been known for some time that sputtered low-density coatings deposited under vacuum (e.g. carbon or B4C), applied on top of high-density metallic coatings, can enhance the reflectivity in the soft x-ray band (below ~5 keV). In the last years, we experimented with novel carbonated coatings obtained by dip-liquid deposition, in which a thin film is formed on the surface of a mirror by immersion in a suitable precursor solution. After several attempts with different chemical compounds, we found an optimal candidate both for the reflectivity performance and for the convenience of the deposition process, which is much simpler and inexpensive compared to conventional processes. In particular, such coatings can enhance the soft x-ray response at the reflection angles employed in future telescopes, like ATHENA (ESA), Lynx (NASA) and eXTP (CAS). In this paper we consider the application of dip-liquid overcoatings on conventional coatings (Au, Ir) or in combination with recently proposed chromium overcoatings and their possible uses to enhance the reflectivity of x-ray mirrors at low, medium or higher energies, presenting the first experimental results of x-ray tests on these coatings. KW - astronomical telescopes KW - soft x-ray KW - reflectivity enhancement KW - dopamine overcoatings KW - Röntgenspiegel KW - Röntgenteleskop Y1 - 2022 UR - https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12181/2630212/Dopamine-dip-liquid-overcoatings-for-soft-x-ray-reflectivity-enhancement/10.1117/12.2630212.short U6 - https://doi.org/10.1117/12.2630212 VL - 2022 IS - 12181 SP - 1218117 EP - 1218117 ER - TY - CHAP A1 - Rivolta, Giacomo A1 - Bruni, Ricardo A1 - Civitani, Marta Maria A1 - Cotroneo, Vincenzo A1 - Döhring, Thorsten A1 - Gibertini, Eugenio A1 - Magagnin, Luca A1 - Pareschi, Giovanni A1 - Romaine, Suzanne A1 - Sethares, Leandra A1 - Sironi, Giorgia A1 - Tagliaferri, Gianpiero A1 - Valsecchi, Giuseppe T1 - Development in carbon-based coatings for X-ray astronomy T2 - IWXM 2022, 7th International Workshop on Metrology for X-ray Optics, Mirror Design and Fabrication, Berlin, 5th - 8th April 2022 KW - x-ray astronomy KW - carbon-based coatings KW - x-ray telescopes KW - Röntgenastronomie KW - Röntgenteleskop Y1 - 2022 ER - TY - JOUR A1 - Wissel, Julian A1 - Freudenmann, Dominic A1 - Cichocka, Magdalena Ola A1 - Pöhl, Almut A1 - Stephan-Hofmann, Iris A1 - Röcke, Nicole A1 - Pérez, Nicolás A1 - Döhring, Thorsten A1 - Stadtmüller, Johannes A1 - Stollenwerk, Manfred T1 - Microstructure of highly effective platinum–iridium alloys as catalysts for hydrogen peroxide decomposition JF - Research on Chemical Intermediates KW - Iridium KW - Katalysator KW - Raumfahrttechnik KW - Antrieb, Technik KW - Wasserstoffperoxyd Y1 - 2024 U6 - https://doi.org/10.1007/s11164-024-05412-4 SN - 0922-6168 VL - 50 IS - 11 SP - 5385 EP - 5397 PB - Springer Science and Business Media LLC ER - TY - CHAP A1 - Stanik, Eva A1 - Stollenwerk, Manfred A1 - Hübner, Sophie A1 - Stadtmüller, Johannes A1 - Döhring, Thorsten T1 - Experimental studies on iridium catalysts for water PEM electrolysis T2 - MaterialsWeek 2025 – Book of Abstracts N2 - The enhanced use of sustainable energy sources entails strong fluctuations in the availability of electric power. As we need new approaches for energy distribution and energy storage systems, hydrogen is often discussed as a promising energy carrier. PEM electrolysis can be used to transform electrical energy from renewable sources into hydrogen. One challenge in this context is the need for catalysts, as these contribute significantly to the performance of the electrolysis cell. The commonly used platinum group metal (PGM) catalysts like Iridium are quite scarce and therefore expensive. A possible approach to reduce the Ir content is the application of magnetron sputtering for catalyst generation. By selecting the right process parameters, the desired layer properties can be set very precisely during sputtering. This ensures a large surface area with reduced material usage. The introduction of carbon can increase the surface area of the catalyst further and enhance its effectiveness. First results of investigations on the catalytic effect of sputtered Ir catalyst layers will be presented. KW - catalyst KW - iridium KW - PEM electrolysis KW - hydrogen KW - magnetron sputtering KW - Iridium KW - Katalysator KW - Wasserstoffenergietechnik Y1 - 2025 SN - 978-3-88355-446-4 SP - 62 EP - 62 PB - Deutsche Gesellschaft für Materialkunde e.V. (DGM) CY - Sankt Augustin ER -