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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 15: Poster Session I
CPP 15.60: Poster
Monday, March 17, 2025, 19:00–21:00, P4
Intermolecular bonds - connecting structure and dynamics — •Martin Tress1, Friedrich Kremer1, and Jan Philipp Gabriel2 — 1Peter-Debye-Institute for Soft Matter Research, Leipzig University, Leipzig, Germany — 2Institute of Materials Physics in Space, German Aerospace Center, Köln, Germany
Descriptions of the glass transition often consider temperature dependent changes in the specific volume to explain the tremendous increase in relaxation time, and empricial data confirm the general role of thermal expansion [Nat Phys 19 (2023) 694]. However, since glassy dynamics happens on molecular scale, macroscopic thermal expansion might be too coarse. Here we use infrared spectroscopy data to extract inter-molecular hydrogen (H)-bond lengths in wide temperature ranges. For water, the H-bond expansion coefficient differs strongly from the macroscopic one, which is easily assigned to considerable structural reorganization in the water network [JCP 160 (2024) 234502]. Their comparison reveals that the most compact molecular arrangement is formed in the range ~316-331 K (i.e. well above the density maximum). This coincides with several pressure-related anomalies which confirms this characteristic point in the supra-molecular arrangement. These results confirm our earlier approach to deduce inter-molecular H-bond lengths in polyalcohols [JCP 154 (2021) 024503] and open a new alley to investigate the role of inter-molecular expansion as a precursor to structural relaxation on a bond-specific level.
Keywords: inter-molecular hydrogen bond expansion; Infrared Spectroscopy; structural relaxation; water anomalies; glycerol