Berlin 2015 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 11: Colloids and Complex Liquids II (joint session CPP/ DY)

DY 11.10: Vortrag

Montag, 16. März 2015, 17:30–17:45, C 130

Supramolecular structure of pure and mixed monohydroxy alcohols — •Thomas Büning¹, Christian Sternemann¹, Sebastian Peter Bierwirth¹, Catalin Gainaru¹, Jennifer Bolle¹, Michael Paulus¹, Christoph J. Sahle², Roland Böhmer¹, and Metin Tolan¹ — ¹Fakultät Physik / DELTA, Technische Universität Dortmund, D-44221 Dortmund, Germany — ²European Synchrotron Radiation Facility (ESRF), F-38000 Grenoble, France

Hydrogen bonds are essential for the structure and dynamics of alcohols, aqueous solutions, and water. Due to their low tendency of crystallization and large variability in molecular configuration, monohydroxy alcohols (MAs) are often studied as model systems for hydrogen-bonded fluids in general [1]. MAs are supposed to form supramolecular structures such as chains and rings via hydrogen bonding in the liquid phase. Based on their small dielectric absorption, ringlike arrangements were suggested for neat MAs with a sterically hindered polar hydroxyl group [1], e.g., for 4-methyl-3-heptanol and 2-hexyl-1-decanol. Mixtures of these MAs show a significantly enhanced dielectric absorption which hints at a change of supramolecular topology [2]. We present combined X-ray diffraction and X-ray Raman measurements of MA mixtures. Here, the first X-ray diffraction peak and the shape of the oxygen K-edge, respectively, are sensitive to the local arrangement of MAs. The results are interpreted with respect to a transformation from ringlike to chainlike structures upon mixing. [1] R. Böhmer et al. Phys. Reports 545 125-195 (2014) and references therein; [2] S. P. Bierwirth, et al. Phys. Rev. E 90, 052807 (2014).