Decoding Oxyanion Aqueous Solvation Structure: A Potassium Nitrate Example at Saturation

Hsiu Wen Wang, Lukas Vlcek, Joerg C. Neuefeind, Katharine Page, Stephan Irle, J. Michael Simonson, Andrew G. Stack

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The ability to probe the structure of a salt solution at the atomic scale is fundamentally important for our understanding of many chemical reactions and their mechanisms. The capability of neutron diffraction to "see" hydrogen (or deuterium) and other light isotopes is exceptional for resolving the structural complexity around the dissolved solutes in aqueous electrolytes. We have made measurements using oxygen isotopes on aqueous nitrate to reveal a small hydrogen-bonded water coordination number (3.9 ± 1.2) around a nitrate oxyanion. This is compared to estimates made using the existing method of nitrogen isotope substitution and those of computational simulations (>5-6 water molecules). The low water coordination number, combined with a comparison to classical molecular dynamics simulations, suggests that ion-pair formation is significant. This insight demonstrates the utility of experimental diffraction data for benchmarking atomistic computer simulations, enabling the development of more accurate intermolecular potentials.

Original languageEnglish
Pages (from-to)7584-7589
Number of pages6
JournalJournal of Physical Chemistry B
Volume122
Issue number30
DOIs
StatePublished - Aug 2 2018

Funding

This material is based upon work supported by the U.S. Department of Energy (DOE), Office of Science (SC), Office of Basic Energy Sciences (BES), Chemical Sciences, Geosciences, and Biosciences Division. The NOMAD instrument at ORNL's SNS is sponsored by the DOE, SC, BES, Scientific User Facilities Division. This material is based upon work supported by the U.S. Department of Energy (DOE), Office of Science (SC), Office of Basic Energy Sciences (BES), Chemical Sciences, Geosciences, and Biosciences Division. The NOMAD instrument at ORNL’s SNS is sponsored by the DOE, SC, BES, Scientific User Facilities Division.

FundersFunder number
Office of Basic Energy Sciences
U.S. Department of Energy
Office of Science
Basic Energy Sciences
Chemical Sciences, Geosciences, and Biosciences Division

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