title: Highly compressed two-dimensional form of water at ambient conditions.
abstract: The structure of thin-film water on a BaF(2)(111) surface under ambient conditions was studied using x-ray absorption spectroscopy from ambient to supercooled temperatures at relative humidity up to 95%. No hexagonal ice-like structure was observed in spite of the expected templating effect of the lattice-matched (111) surface. The oxygen K-edge x-ray absorption spectrum of liquid thin-film water on BaF(2) exhibits, at all temperatures, a strong resemblance to that of high-density phases for which the observed spectroscopic features correlate linearly with the density. Surprisingly, the highly compressed, high-density thin-film liquid water is found to be stable from ambient (300 K) to supercooled (259 K) temperatures, although a lower-density liquid would be expected at supercooled conditions. Molecular dynamics simulations indicate that the first layer water on BaF(2)(111) is indeed in a unique local structure that resembles high-density water, with a strongly collapsed second coordination shell.
authors: SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
authors: Sarp
authors: S
authors: Kaya
authors: Daniel
authors: D
authors: Schlesinger
authors: Susumu
authors: S
authors: Yamamoto
authors: John T
authors: JT
authors: Newberg
authors: Hendrik
authors: H
authors: Bluhm
authors: Hirohito
authors: H
authors: Ogasawara
authors: Tom
authors: T
authors: Kendelewicz
authors: Gordon E
authors: GE
authors: Brown
authors: Lars G M
authors: LG
authors: Pettersson
authors: Anders
authors: A
authors: Nilsson