@article{SchmittFeldeDoehringetal.2022, author = {Schmitt, Paul and Felde, Nadja and D{\"o}hring, Thorsten and Stollenwerk, Manfred and Uschmann, Ingo and Hanemann, Kevin and Siegler, Marie and Klemm, Georg and Gratzke, Nancy and T{\"u}nnermann, Andreas and Schwinde, Stefan and Schr{\"o}der, Sven and Szeghalmi, Adriana}, title = {Optical, structural, and functional properties of highly reflective and stable iridium mirror coatings for infrared applications}, series = {Optical Materials Express}, volume = {2022}, journal = {Optical Materials Express}, number = {12 / 2}, doi = {10.1364/OME.447306}, pages = {545 -- 559}, year = {2022}, abstract = {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.}, subject = {Iridium}, language = {en} } @article{SchmittFeldeDoehringetal.2022, author = {Schmitt, Paul and Felde, Nadja and D{\"o}hring, Thorsten and Stollenwerk, Manfred and Uschmann, Ingo and Hanemann, Kevin and Siegler, Marie and Klemm, Georg and Gratzke, Nancy and T{\"u}nnermann, Andreas and Schwinde, Stefan and Schr{\"o}der, Sven and Szeghalmi, Adriana}, title = {Optical, structural, and functional properties of highly reflective and stable iridium mirrorcoatings for infrared applications: supplement}, series = {Optical Materials Express}, volume = {2022}, journal = {Optical Materials Express}, number = {12/2}, doi = {10.6084/m9.figshare.17121509}, pages = {545 -- 559}, year = {2022}, abstract = {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.}, subject = {Iridium}, language = {en} } @inproceedings{DoehringStieglitzHudecetal.2022, author = {D{\"o}hring, Thorsten and Stieglitz, Veronika and Hudec, Rene and Sapsai, Iryna and Friedrich, Peter and Burwitz, Vadim}, title = {Characterization of a lobster-eye type X-ray telescope}, series = {EPJ Web of Conferences}, volume = {266 (2022)}, booktitle = {EPJ Web of Conferences}, doi = {10.1051/epjconf/202226613010}, pages = {1 -- 2}, year = {2022}, abstract = {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.}, subject = {R{\"o}ntgenteleskop}, language = {de} } @article{StieglitzBurwitzDoehringetal.2022, author = {Stieglitz, Veronika and Burwitz, Vadim and D{\"o}hring, Thorsten and Hudec, Rene and Vitek, Stanislav}, title = {Design and testing of a Kirkpatrick-Baez optics variation}, series = {EPJ Web of Conferences}, volume = {266 (2022)}, journal = {EPJ Web of Conferences}, doi = {10.1051/epjconf/202226603021}, pages = {1 -- 2}, year = {2022}, abstract = {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}, subject = {R{\"o}ntgenoptik}, language = {en} } @inproceedings{MannDoehringStollenwerketal.2024, author = {Mann, Michael and D{\"o}hring, Thorsten and Stollenwerk, Manfred and Priebsch, Alessandro and Pribulla, Theodor and Komž{\´i}k, Richard M. and Sivanic, Peter}, title = {Advanced power quality measurement techniques at the electric power grid of astronomical observatories}, series = {Observatory Operations: Strategies, Processes, and Systems X, Conference of SPIE 13098, 17 - 20 June 2024}, booktitle = {Observatory Operations: Strategies, Processes, and Systems X, Conference of SPIE 13098, 17 - 20 June 2024}, editor = {Storrie-Lombardi, Lisa J. and Benn, Chris R. and Chrysostomou, Antonio}, publisher = {SPIE}, doi = {10.1117/12.3016562}, year = {2024}, subject = {Sternwarte}, language = {en} } @inproceedings{ErmilovaHertwigDoehringetal.2024, author = {Ermilova, Elena and Hertwig, Andreas and D{\"o}hring, Thorsten and Stanik, Eva and Cotroneo, Vincenzo and Gibertini, Eugenio}, title = {Ellipsometrische Charakterisierung von Polydopamin f{\"u}r funktionelle technische Schichten}, series = {DGaO-Proceedings}, volume = {2024}, booktitle = {DGaO-Proceedings}, number = {125}, pages = {1 -- 2}, year = {2024}, abstract = {D{\"u}nne Schichten aus dem bionischen Material Polydopamin (PDA) sind heute zunehmend auch f{\"u}r innovative technische Anwendungen von Interesse. Mittels spektroskopischer Ellipsometrie wurde die dielektrische Funktion von PDA vom ultravioletten bis zum nahen infraroten Spektralbereich vermessen. {\"U}ber ein Modell wurde auch die Dicke dieser selbstorganisierenden Schichten bestimmt.}, subject = {D{\"u}nne Schicht}, language = {de} } @article{AmorimSperaNicoaraetal.2024, author = {Amorim, Isilda and Spera, Natalia C.M. and Nicoara, Nicoleta and Ramasamy, Devaraj and Alves, Diana F. and Stollenwerk, Manfred and Stadtm{\"u}ller, Johannes and D{\"o}hring, Thorsten and Sadewasser, Sascha and Kolen'ko, Yury V. and Sousa, Juliana P.S.}, title = {Overall alkaline water electrolysis over active, stable, low loading iridium catalysts sputtered on nickel foam}, series = {International Journal of Hydrogen Energy}, volume = {92}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier BV}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.10.306}, pages = {852 -- 864}, year = {2024}, subject = {Iridium}, language = {en} } @misc{StanikDoehringZeisingetal.2024, author = {Stanik, Eva and D{\"o}hring, Thorsten and Zeising, Sebastian and Meißner, Martin}, title = {An astronomy event at Aschaffenburg University to attract future engineering students}, series = {18th INTEGRAL/BART Workshop}, volume = {2024}, journal = {18th INTEGRAL/BART Workshop}, organization = {TH Aschaffenburg}, pages = {1 -- 1}, year = {2024}, abstract = {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.}, subject = {Astronomie}, language = {en} } @inproceedings{StanikDoehringPregleretal.2024, author = {Stanik, Eva and D{\"o}hring, Thorsten and Pregler, Jan and K{\"a}tker, Anna and Busch, Uwe and Friedrich, Peter}, title = {A visitor experiment on astronomical X-ray optics for the "Deutsches R{\"o}ntgen-Museum"}, series = {AXRO 2024 - 15th International Conference on Astronomical X-Ray Optics}, volume = {2024}, booktitle = {AXRO 2024 - 15th International Conference on Astronomical X-Ray Optics}, organization = {TH Aschaffenburg}, pages = {1 -- 1}, year = {2024}, abstract = {The "Deutsches R{\"o}ntgenmuseum" in Remscheid is the unique institution worldwide that researches and documents the life and work of the first Nobel Prize winner, Wilhelm Conrad R{\"o}ntgen, and the effects of his discovery of X-rays. As an integral part of the museum, the R{\"o}Lab 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 R{\"o}ntgenmuseum" intend to inspire young researchers for the fascinating world of X-ray optics and X-ray astronomy.}, subject = {Deutsches R{\"o}ntgen-Museum}, language = {en} } @incollection{WisselFreudenmannPerezetal.2025, author = {Wissel, Julian and Freudenmann, Dominic and Perez, Nicolas and D{\"o}hring, Thorsten and Stadtm{\"u}ller, Johannes and Stollenwerk, Manfred}, title = {Various highly effective sputtered layer structures as catalysts for H2O2 decomposition for use in satellite engines}, series = {MaterialsWeek 2025 - Book of Abstracts}, booktitle = {MaterialsWeek 2025 - Book of Abstracts}, publisher = {Deutsche Gesellschaft f{\"u}r Materialkunde e.V. (DGM)}, address = {Sankt Augustin}, isbn = {978-3-88355-446-4}, pages = {53 -- 53}, year = {2025}, abstract = {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.}, subject = {Satellitentechnik}, language = {en} } @inproceedings{CotroneoBruniCivitanietal.2022, author = {Cotroneo, Vincenzo and Bruni, Ricardo and Civitani, Marta Maria and D{\"o}hring, Thorsten and Gibertini, Eugenio and Magagnin, Luca and Pareschi, Giovanni and Rivolta, Giacomo and Romaine, Suzanne and Sethares, Leandra and Sironi, Giorgia and Tagliaferri, Gianpiero and Valsecchi, Giuseppe}, title = {Dopamine dip-liquid overcoatings for soft X-ray reflectivity enhancement}, series = {Proceedings of SPIE}, volume = {2022}, booktitle = {Proceedings of SPIE}, number = {12181}, doi = {10.1117/12.2630212}, pages = {1218117 -- 1218117}, year = {2022}, abstract = {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.}, subject = {R{\"o}ntgenspiegel}, language = {en} } @inproceedings{RivoltaBruniCivitanietal.2022, author = {Rivolta, Giacomo and Bruni, Ricardo and Civitani, Marta Maria and Cotroneo, Vincenzo and D{\"o}hring, Thorsten and Gibertini, Eugenio and Magagnin, Luca and Pareschi, Giovanni and Romaine, Suzanne and Sethares, Leandra and Sironi, Giorgia and Tagliaferri, Gianpiero and Valsecchi, Giuseppe}, title = {Development in carbon-based coatings for X-ray astronomy}, series = {IWXM 2022, 7th International Workshop on Metrology for X-ray Optics, Mirror Design and Fabrication, Berlin, 5th - 8th April 2022}, booktitle = {IWXM 2022, 7th International Workshop on Metrology for X-ray Optics, Mirror Design and Fabrication, Berlin, 5th - 8th April 2022}, year = {2022}, subject = {R{\"o}ntgenastronomie}, language = {en} }