@inproceedings{DoehringStadtmuellerStollenwerketal.2021, author = {D{\"o}hring, Thorsten and Stadtm{\"u}ller, Johannes and Stollenwerk, Manfred and Cotroneo, Vincenzo and Pareschi, Giovanni and Gibertini, Eugenio and Magagnin, Luca}, title = {Low-density coatings for enhanced X-ray reflectivity of astronomical telescope mirrors}, series = {DGaO Proceedings}, volume = {2021}, booktitle = {DGaO Proceedings}, number = {122}, publisher = {DGaO}, organization = {TH Aschaffenburg}, issn = {1614-8436}, pages = {1 -- 2}, year = {2021}, abstract = {High reflectivity grazing incidence mirrors of astronomical X-ray telescopes are usually coated with thin layers of iridium, gold, or platinum. Due to a series of absorption edges, these noble metals have low reflectivity in the 2 - 4 keV band. We present the development of innovative material combinations using chromium and an additional layer of polydopamine for enhanced reflectivity X-ray coatings.}, subject = {R{\"o}ntgenteleskop}, language = {en} } @misc{DoehringStadtmuellerStollenwerketal.2021, author = {D{\"o}hring, Thorsten and Stadtm{\"u}ller, Johannes and Stollenwerk, Manfred and Cotroneo, Vincenzo and Pareschi, Giovanni and Gibertini, Eugenio and Magagnin, Luca}, title = {Low-density coatings for enhanced X-ray reflectivity of astronomical telescope mirrors}, series = {DGaO Jahrestagung}, volume = {2021}, journal = {DGaO Jahrestagung}, organization = {TH Aschaffenburg}, pages = {1 -- 1}, year = {2021}, abstract = {X-ray telescopes usually operate in space and are quite different from astronomical telescopes for visible light. For normal angles of incidence, optical light is reflected on the mirror surface, whereas X-rays are either transmitted or absorbed. However, also high reflectivity X-rays mirrors are possible, when the incident rays direction is almost parallel to the mirror surface. Such grazing incidence mirrors are usually coated with thin layers of precious metals like iridium, gold or platinum, as this result in high X-ray reflectivity. These noble metals offer a wide range of reflection up to high photon energies, but, due to a series of absorption edges, have low reflectivity in the 2 - 4 keV band and below. This contribution presents the development of innovative material combinations based on thin layers of iridium and chromium, followed by an additional layer of carbon-based materials. We also discuss corresponding production methods (like dip coating) for enhanced reflectivity mirror coatings of future X-ray telescopes.}, subject = {R{\"o}ntgenstrahlung}, language = {en} } @inproceedings{CotroneoBruniDoehringetal.2021, author = {Cotroneo, Vincenzo and Bruni, Ricardo and D{\"o}hring, Thorsten and Ferreira, Desiree and Gibertini, Eugenio and Henriksen, Peter and Magagnin, Luca and Massahi, Sonny and Pareschi, Giovanni and Romaine, Suzanne and Sethares, Leandra and Sironi, Giorgia and Spiga, Daniele and Tagliaferri, Gianpiero and Valsecchi, Giuseppe}, title = {Development of low-density coatings for soft x-ray reflectivity enhancement for ATHENA and other missions}, series = {Proceedings of SPIE}, volume = {2021}, booktitle = {Proceedings of SPIE}, number = {11852}, publisher = {SPIE}, organization = {Osservatorio Astronomico di Brera}, doi = {https://doi.org/10.1117/12.2599803}, pages = {118524P-1 -- 118524P-13}, year = {2021}, abstract = {Metallic coatings made of precious metals (e.g. Ir, Pt or Au) with high atomic number Z have been traditionally employed at grazing incidence for X-rays reflection and focalization. These materials offer a range of reflection extended to higher energies, but also present a series of absorption edges, which limit the reflectivity in the 2-4 keV band and below. Therefore the search for alternative coatings, able to improve the reflection in the soft energy range, is particularly relevant for the development of future telescopes, like ATHENA (ESA), Lynx (NASA) and eXTP (CAS). Low-Z overcoatings (e.g. carbon or B4C), applied on top of the high-Z metallic layer, can enhance the reflectivity in the softer band (mainly below 2 keV), but conventional deposition methods for these materials are not easily compatible with some of the mainstream technologies for mirror fabrication (notably, the silicon pore optics that will be used for the ATHENA X-ray mission which is being implemented by ESA). In this work we discuss novel solutions (carbon-like overcoatings realized by dip coating or vapor phase deposition), which can be particularly convenient for the application to ATHENA and to future telescopes.}, subject = {R{\"o}ntgenteleskop}, language = {en} } @misc{GiovanniDoehringValsecchietal.2019, author = {Giovanni, Pareschi and D{\"o}hring, Thorsten and Valsecchi, Guiseppe and Magagnin, Luca and Bradshaw, Miranda and Burwitz, Vadim and Civitani, Marta Maria and Cotroneo, Vincenzo and Gibertini, Eugenio and Pelliciari, Carlo and Sironi, Giorgia and Yang, Yang}, title = {Enhancing the ATHENA effective area at low x-ray energies with unconventional overcoatings}, series = {Proceedings of the X-RAY ASTRONOMY 2019 conference}, volume = {2019}, journal = {Proceedings of the X-RAY ASTRONOMY 2019 conference}, organization = {Istituto Nazionale di Astrofisica}, pages = {1 -- 1}, year = {2019}, abstract = {Low density overcoatings (mainly based on materials containing Carbon) onto usual hi Z materials (like Ir, Au or Pt) have been proposed more than 10 years ago for enhancing the X-ray reflectivity at low energy (between 0.5 and 4 keV) in X-ray astronomical optics. The hack is to use the total reflection from the low density material (which do not suffer much the photoelectric absorption) at low energy, while the photons at high energy are reflected by the high density material. Now for several future projects like e.g. ATHENA and eXTP it is foreseen the use of low density overcoatings that will importantly increase the effective area at low energy. In this poster we will discuss about the use of materials different from the ones considered so far, in particular based on a thin layer of Chromium followed by another layer of a Carbon-like material, and of novel approaches for their application.}, subject = {R{\"o}ntgenteleskop}, language = {en} } @misc{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}, organization = {Bundesanstalt f{\"u}r Materialforschung und -pr{\"u}fung}, year = {2024}, abstract = {Obwohl das organische Molek{\"u}l Dopamin (3,4-Dihydroxyphenethylamin) allgemein eher als „Gl{\"u}ckshormon" bekannt ist, sind d{\"u}nne Schichten aus Polydopamin heute zunehmend auch f{\"u}r innovative technische Anwendungen von Interesse. Ein Beispiel sind reflexionsverst{\"a}rkende Beschichtungen f{\"u}r astronomische R{\"o}ntgenspiegel. Bei der Herstellung durch eine Tauchbeschichtung wachsen die selbstorganisierenden Polydopamin-Schichten in Einzel- oder Mehrfach-Molek{\"u}llagen mit reproduzierbaren Dicken von wenigen Nanometern auf. Mit der Methode der spektroskopischen Ellipsometrie wurde die dielektrische Funktion von Polydopamin vom ultravioletten bis zum nahen infraroten Spektralbereich zun{\"a}chst bei Modellschichten ausreichender Dicke vermessen. {\"U}ber ein optisches Modell wurden diese Daten dann zur Bestimmung der Schichtdicken deutlich d{\"u}nnerer Polydopamin-Schichten verwendet. Das Ergebnis dieser Studie erm{\"o}glicht ein besseres Verst{\"a}ndnis des Zusammenhangs von Schichtdicken und Schichteigenschaften in Abh{\"a}ngigkeit von den gew{\"a}hlten Prozessparametern. Dar{\"u}ber hinaus wird ein Ausblick auf potentielle weitere technische Anwendungen des interessanten bionischen Materials Polydopamin gegeben.}, subject = {D{\"u}nne Schicht}, language = {de} } @inproceedings{ErmilovaHertwigDoehringetal.2024, author = {Ermilova, Elena and Hertwig, Andreas and D{\"o}hring, Thorsten and Stanik, Eva and Cotroneo, Vincenzo and Gibertini, Eugenio}, title = {Ellipsometrical characterization of poly-dopamine layers considered for technical applications}, series = {Proceedings of SPIE}, volume = {2024}, booktitle = {Proceedings of SPIE}, number = {13013}, doi = {https://doi.org/10.1117/12.3015281}, pages = {1301309-1 -- 1301309-8}, year = {2024}, abstract = {Although the organic molecule dopamine (3,4-dihydroxyphenethylamine) is commonly known as the "hormone of happiness", thin films of poly-dopamine also have interesting technical properties. When produced by dip coating, the self-organizing layers grow in a reproducible thickness of single or multiple molecule monolayers of a few nanometer thickness only. In this work, we introduce a method of determining the layer thickness of poly-dopamine on mirrors for astronomical X-ray telescopes. This work is based on spectroscopic ellipsometry measurements and involves the development of an optical model for the poly-dopamine layers including the dielectric function. Thereby the complex refractive index of the produced layers was determined, covering the range from the ultraviolet to the near infrared spectral region. These measurement results and the corresponding technical challenges are presented in this contribution. Furthermore, an outlook to potential technical applications of this interesting material is given and poly-dopamine layers will make scientist and engineers hopefully happy as an innovative and fascinating technical solution for the future.}, subject = {D{\"u}nne Schicht}, 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} } @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} } @article{CotroneoBassoCivitanietal.2025, author = {Cotroneo, Vicenzo and Basso, Stefano and Civitani, Marta and D{\"o}hring, Thorsten and Gibertini, Eugenio and Iovenitti, Simone and Magagnin, Luca and Pareschi, Giovanni and Sironi, Giorgia and Spiga, Daniele and Tagliaferri, Gianpiero and Valsecchi, Giuseppe}, title = {Polydopamine Coatings for Enhanced Soft X-Ray Reflectivity in Space Telescope Mirrors}, series = {ECS Meeting Abstracts}, volume = {MA2025-02}, journal = {ECS Meeting Abstracts}, number = {67}, publisher = {The Electrochemical Society}, issn = {2151-2043}, doi = {10.1149/MA2025-02673247mtgabs}, pages = {3247 -- 3247}, year = {2025}, abstract = {It has been known for years that sputtered low-density coatings deposited under vacuum (e.g. carbon or B4C), applied on top of high-density metallic coatings, can enhance their reflectivity in the soft X-ray band (below ~5 keV). However, the physical deposition techniques, as vacuum-based sputtering, to produce B4C or amorphous coatings are usually difficult and highly costing. Polydopamine (PDA), a bio-polymer inspired by mussels, exhibits exceptional surface binding and it's nowadays a popular material used in surface engineering for multipurpose applications (Ryu, 2018). PDA thin film are typically produced in aqueous solution by the oxidative polymerization of dopamine, commonly known as one of the "hormones of happiness", resulting in nanometric PDA coating with tunable thickness and morphology. In recent years, we have introduced and investigated a novel and scalable strategy for enhancing the soft X-ray reflectivity of telescope mirrors used in space missions based on dip-liquid deposition of PDA thin films as carbon-rich coating (carbon 62.7 \%wt. in DA monomer) (Cotroneo, 2022). This method is very versatile and quick and offers a low-cost alternative to conventional carbon-like coating, while maintaining or even exceeding performance in the energy range below ~5 keV. Experimental tests across three X-ray beamlines—including two synchrotron facilities—demonstrated consistent reflectivity enhancement, especially in the 1-4 keV energy range and with a good match between theoretical predictions and experimental reflectivity profiles. When applied over traditional coatings (e.g Au, Ir), the dip-liquid overcoats produced improvements of up to 100\% in effective area for some specific X-ray bands compared to conventional single-metal films. These results are particularly compelling for nickel-replicated mirrors with gold coatings, a common architecture in cost-sensitive space missions. Bibliography Cotroneo, V., 2022. Dopamine dip-liquid overcoatings for soft x-ray reflectivity enhancement. SPIE Proceedings. Ryu, J. H., 2018. Polydopamine Surface Chemistry: A Decade of Discovery. ACS Applied Materials \& Interfaces.}, subject = {R{\"o}ntgenteleskop}, language = {en} } @inproceedings{KhropostRiethmuellerDoehringetal.2025, author = {Khropost, Diana and Riethm{\"u}ller, Franziska and D{\"o}hring, Thorsten and Flachs, Dennis and H{\"u}lag{\"u}, Deniz and Hertwig, Andreas and Cotroneo, Vincenzo and Gibertini, Eugenio}, title = {Polydopamine: a bio-inspired polymer for X-ray mirror coatings and other technical applications}, series = {EUV and X-ray Optics: Synergy between Laboratory and Space IX}, volume = {2025}, booktitle = {EUV and X-ray Optics: Synergy between Laboratory and Space IX}, number = {13531}, editor = {Hudec, Ren{\´e} and Pina, Ladislav}, publisher = {SPIE}, doi = {10.1117/12.3056298}, pages = {135310H-1 -- 135310H-11}, year = {2025}, abstract = {Although the organic molecule dopamine (3,4-dihydroxyphenethylamine) is commonly known as one of the "hormones of happiness", thin polymer films of polydopamine (PDA) also have interesting technical properties. PDA is a very strong glue that sticks on almost everything, even under water. In nature, PDA is found in the byssal thread cuticles of mussels. When produced by dip-coating, the self-organizing PDA layers grow in a reproducible thickness of single or multiple molecule monolayers of a few nanometres thickness only. Here we present an optimized preparation regime as derived from polymerization analysis through absorption spectroscopy. One application is the use of thin PDA overcoatings to increase the soft X-ray reflectivity of astronomical X-ray mirrors. Furthermore, we give an outlook to other technical applications for this interesting material, presenting this bio-inspired organic polymer as an innovative technical solution for the future, with applications such as PDA-based super-capacitors and its promising role in enhancing separator materials for batteries.}, subject = {R{\"o}ntgenspiegel}, language = {en} }