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Title: Hydration structure of the barite (001)–water interface: Comparison of x-ray reflectivity with molecular dynamics simulations

Abstract

The three-dimensional structure of the barite (001)-water interface was studied using in situ specular and non-specular X-ray reflectivity (XR). Displacements of the barium and sulfate ions in the surface of a barite crystal and the interfacial water structure were defined in the analyses. The largest relaxations (0.13 Å lateral and 0.08 Å vertical) were observed for the barium and sulfate ions in the topmost unit cell layer, which diminished rapidly with depth. The best fit structure identified four distinct adsorbed species, which in comparison with molecular dynamics (MD) simulations, reveals that they are associated with positions of adsorbed water, each of which coordinates one or two surface ions (either barium, sulfate, or both). These water molecules also adsorb in positions consistent with those of bariums and sulfates in the bulk crystal lattice. These results demonstrate the importance of combining high resolution XR with MD simulations to fully describe the atomic structure of the hydrated mineral surface. As a result, the agreement between the results indicates both the uniqueness of the structural model obtained from the XR analysis and the accuracy of the force field used in the simulations.

Authors:
ORCiD logo [1];  [1];  [2];  [2]; ORCiD logo [3]; ORCiD logo [1]; ORCiD logo [4]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Univ. of Chicago, Chicago, IL (United States)
  3. Karlsruher Institute fur Technologie, Karlsruhe (Germany)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1364403
Alternate Identifier(s):
OSTI ID: 1376531
Grant/Contract Number:  
AC02-06CH11357; AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 22; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; barite; interface; molecular dynamics simulations; x-ray reflectivity

Citation Formats

Bracco, Jacquelyn N., Lee, Sang Soo, Stubbs, Joanne E., Eng, Peter J., Heberling, Frank, Fenter, Paul, and Stack, Andrew G. Hydration structure of the barite (001)–water interface: Comparison of x-ray reflectivity with molecular dynamics simulations. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.7b02943.
Bracco, Jacquelyn N., Lee, Sang Soo, Stubbs, Joanne E., Eng, Peter J., Heberling, Frank, Fenter, Paul, & Stack, Andrew G. Hydration structure of the barite (001)–water interface: Comparison of x-ray reflectivity with molecular dynamics simulations. United States. doi:10.1021/acs.jpcc.7b02943.
Bracco, Jacquelyn N., Lee, Sang Soo, Stubbs, Joanne E., Eng, Peter J., Heberling, Frank, Fenter, Paul, and Stack, Andrew G. Thu . "Hydration structure of the barite (001)–water interface: Comparison of x-ray reflectivity with molecular dynamics simulations". United States. doi:10.1021/acs.jpcc.7b02943. https://www.osti.gov/servlets/purl/1364403.
@article{osti_1364403,
title = {Hydration structure of the barite (001)–water interface: Comparison of x-ray reflectivity with molecular dynamics simulations},
author = {Bracco, Jacquelyn N. and Lee, Sang Soo and Stubbs, Joanne E. and Eng, Peter J. and Heberling, Frank and Fenter, Paul and Stack, Andrew G.},
abstractNote = {The three-dimensional structure of the barite (001)-water interface was studied using in situ specular and non-specular X-ray reflectivity (XR). Displacements of the barium and sulfate ions in the surface of a barite crystal and the interfacial water structure were defined in the analyses. The largest relaxations (0.13 Å lateral and 0.08 Å vertical) were observed for the barium and sulfate ions in the topmost unit cell layer, which diminished rapidly with depth. The best fit structure identified four distinct adsorbed species, which in comparison with molecular dynamics (MD) simulations, reveals that they are associated with positions of adsorbed water, each of which coordinates one or two surface ions (either barium, sulfate, or both). These water molecules also adsorb in positions consistent with those of bariums and sulfates in the bulk crystal lattice. These results demonstrate the importance of combining high resolution XR with MD simulations to fully describe the atomic structure of the hydrated mineral surface. As a result, the agreement between the results indicates both the uniqueness of the structural model obtained from the XR analysis and the accuracy of the force field used in the simulations.},
doi = {10.1021/acs.jpcc.7b02943},
journal = {Journal of Physical Chemistry. C},
number = 22,
volume = 121,
place = {United States},
year = {Thu May 11 00:00:00 EDT 2017},
month = {Thu May 11 00:00:00 EDT 2017}
}

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