Nearest-neighbor oxygen distances in liquid water and ice observed by x-ray Raman based extended x-ray absorption fine structure

J Chem Phys. 2007 Nov 7;127(17):174504. doi: 10.1063/1.2784123.

Abstract

We report the nearest-neighbor oxygen-oxygen radial distribution function (NN O-O RDF) of room temperature liquid water and polycrystalline ice Ih (-16.8 degrees C) obtained by x-ray Raman based extended x-ray absorption fine structure (EXAFS) spectroscopy. The spectra of the two systems were taken under identical experimental conditions using the same procedures to obtain the NN O-O RDFs. This protocol ensured a measurement of the relative distance distribution with very small systematic errors. The NN O-O RDF of water is found to be more asymmetric (tail extending to longer distances) with longer average distance (2.81 A for water and 2.76 A for ice) but a slightly shorter peak position (2.70 A for water and 2.71 A for ice). The refinement also showed a small but significant contribution from the linear O-H-O multiple scattering signal. The high sensitivity to short range distances of the EXAFS probe will set further restrictions to the range of possible models of liquid water.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Chemistry, Physical / methods
  • Hydrogen / chemistry
  • Hydrogen Bonding
  • Ice
  • Molecular Structure
  • Oxygen / chemistry
  • Phase Transition
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Spectrum Analysis, Raman / methods*
  • Water / chemistry*
  • X-Ray Diffraction
  • X-Rays

Substances

  • Ice
  • Water
  • Hydrogen
  • Oxygen