Dresden 2026 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: Focus Session: Water – from Atmosphere to Space IV (joint session CPP/DY)

CPP 32.1: Topical Talk

Wednesday, March 11, 2026, 09:30–10:00, ZEU/0260

Synchrotron X-Ray Studies on Structural Transitions in Water and Alcohol containing Ice Analogues — •Christina M. Tonauer — Institute of Physical Chemistry, University of Innsbruck, Austria — Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany

To this date, 21 different crystalline and at least 3 distinct amorphous forms of water ice have been discovered. In addition to the structural versatility of pure water ice phases, water forms solid guest-host systems, so-called 'clathrate hydrates' where water builds cage-like structures around guest molecules of various sizes (e.g., Ar, CO2, methane, ethanol).

Ices in space are exposed to various forms of (external) stress, e.g., impacts, cosmic rays, UV/Vis radiation as well as endogenous thermal fluctuations, thereby undergoing structural changes. By studying such structural transitions in ice analogues upon heating (and/or radiation), conclusions can be drawn about the conditions at various extraterrestrial environments.

Therefore, we here present temperature-resolved wide- and small-angle synchrotron X-ray scattering data of vapor-deposited water-ethanol mixtures of various concentrations, collected at PETRA 3/DESY. While the SAXS data allows for monitoring of changes of the morphology of the microporous sample, the WAXS data reveals the formation sequence of two different hydrates, offering new insights into the crystallisation of astrophysical ices.

Keywords: Ice; phase transitions; WAXS; SAXS; Hydrates