title: Limits of metastability in amorphous ices: the neutron scattering Debye-Waller factor.
abstract: Recently, it became clear that relaxation effects in amorphous ices play a very important role that has previously been overlooked. The thermodynamic history of amorphous samples strongly affects their transition behavior. In particular, well-relaxed samples show higher thermal stability, thereby providing a larger window to investigate their glass transitions. We here present neutron scattering experiments using fixed elastic window scans on relaxed forms of amorphous ice, namely expanded high density amorphous ice (eHDA), a variant of low density amorphous ice (LDA-II) and hyperquenched glassy water (HGW). These amorphous ices are expected to be true glassy counterparts of deeply supercooled liquid water, therefore fast precursor dynamics of structural relaxation are expected to appear below the calorimetric glass transition temperature. The Debye-Waller factor shows a very weak sub-T(g) anomaly in some of the samples, which might be the signature of such fast precursor dynamics. However, we cannot find this behavior consistently in all samples at all reciprocal length scales of momentum transfer.
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria. katrin.winkel@uibk.ac.at
authors.forename: Katrin
authors.initials: K
authors.lastname: Amann-Winkel
authors.forename: Florian
authors.initials: F
authors.lastname: Löw
authors.forename: Philip H
authors.initials: PH
authors.lastname: Handle
authors.forename: Wiebke
authors.initials: W
authors.lastname: Knoll
authors.forename: Judith
authors.initials: J
authors.lastname: Peters
authors.forename: Burkhard
authors.initials: B
authors.lastname: Geil
authors.forename: Franz
authors.initials: F
authors.lastname: Fujara
authors.forename: Thomas
authors.initials: T
authors.lastname: Loerting
mesh_terms: D003460:Crystallization; D007053:Ice / Q000032:analysis*; D013816:Thermodynamics; D044366:Transition Temperature
chemical_list: D007053:Ice