title: Raman spectroscopic evidence for the most stable water/ethanol dimer and for the negative mixing energy in cold water/ethanol trimers.
abstract: Spontaneous Raman scattering in supersonic jet expansions is used to prove that the mixed dimer of ethanol and water (corresponding to a volume fraction of 79% ethanol in the liquid) prefers ethanol in a gauche conformation as the hydrogen bond acceptor. This represents a particularly simple case of adaptive aggregation. Furthermore, it is shown experimentally that the isolated cold trimer built from one ethanol and two waters (corresponding to 64% ethanol in the liquid) has a significantly negative excess enthalpy, in line with the thermodynamic bulk observation at room temperature.
authors.affiliation: Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, Göttingen, Germany.
authors.forename: Marija
authors.initials: M
authors.lastname: Nedić
authors.forename: Tobias N
authors.initials: TN
authors.lastname: Wassermann
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Xue
authors.forename: Philipp
authors.initials: P
authors.lastname: Zielke
authors.forename: Martin A
authors.initials: MA
authors.lastname: Suhm
mesh_terms: D019281:Dimerization; D000431:Ethanol / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D000431:Ethanol