Berlin 2024 – scientific programme
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DS: Fachverband Dünne Schichten
DS 18: Optical Analysis of Organic Thin Films
DS 18.2: Talk
Thursday, March 21, 2024, 17:15–17:30, A 060
Characterisation of thin layers of Polydopamine used as functional coatings in X-Ray optics. — •Andreas Hertwig1, Elena Ermilova1, Vincenzo Cotroneo2, Eugenio Gibertini3, Eva Stanik4, and Thorsten Döhring4 — 1Bundesanstalt für Materialforschung und -prüfung (BAM) — 2INAF - Osservatorio Astronomico di Brera — 3Politecnico di Milano — 4TH Aschaffenburg
Polydopamine (PDA) is a biological / biomimetic polymer which has spiked considerable interest in recent years. Its monomer is an important neurotransmitter and it is one of the strongest glues produced by biological organisms. Polydopamine is a candidate for several applications, mainly in the field of biology and medicine, but also - recently - for layer coatings with optical, electrical, and mechanical function.
In this work, we investigate PDA layers intended as reflectivity enhancers for mirror surfaces in X-ray astronomical observatories. It has previously been shown, that such X-ray telescopes can be improved by a coating of PDA in the thickness range of several nm. Accurate thickness determination is required to monitor and optimise the coating process. We use spectroscopic ellipsometry to determine first the dielectric function of the polydopamine layers using model coatings of sufficient thickness. This data is then used to accurately determine the layer thickness of much thinner PDA layers. This study resulted in data on the thickness and dielectric function of PDA layers that could lead to a better understanding of the correlation of layer thickness and layer properties depending on the process parameters.
Keywords: Spectroscopic Ellipsometry; X-Ray Optics; Poly-Dopamine; Layer Metrology; Optical functional surfaces