Compatibility of quantitative X-ray spectroscopy with continuous distribution models of water at ambient conditions



: Johannes Niskanen, Mattis Fondell, Christoph J. Sahle, Sebastian Eckert, Raphael M. Jay, Keith Gilmore, Annette Pietzsch, Marcus Dantz, Xingye Lu, Daniel E. McNally, Thorsten Schmitt, Vinicius Vaz da Cruz, Victor Kimberg, Faris Gel’mukhanov, Alexander Föhlisch

Publisher: NATL ACAD SCIENCES

: 2019

: Proceedings of the National Academy of Sciences of the United States of America

: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA

: P NATL ACAD SCI USA

: 116

: 10

: 4058

: 4063

: 6

: 0027-8424

DOI: https://doi.org/10.1073/pnas.1815701116

: https://research.utu.fi/converis/portal/detail/Publication/39918592


The phase diagram of water harbors controversial views on underlying structural properties of its constituting molecular moieties, its fluctuating hydrogen-bonding network, as well as pair-correlation functions. In this work, long energy-range detection of the X-ray absorption allows us to unambiguously calibrate the spectra for water gas, liquid, and ice by the experimental atomic ionization cross-section. In liquid water, we extract the mean value of 1.74 +/- 2.1% donated and accepted hydrogen bonds per molecule, pointing to a continuous-distribution model. In addition, resonant inelastic X-ray scattering with unprecedented energy resolution also supports continuous distribution of molecular neighborhoods within liquid water, as do X-ray emission spectra once the femtosecond scattering duration and proton dynamics in resonant X-ray-matter interaction are taken into account. Thus, X-ray spectra of liquid water in ambient conditions can be understood without a two-structure model, whereas the occurrence of nanoscale-length correlations within the continuous distribution remains open.

Last updated on 2024-26-11 at 21:29