Real-time probing of hydrogen-bond exchange dynamics in aqueous NaPF 6 solutions by two-dimensional infrared spectroscopy

Hyewon Son, Dayoung Nam, Sungnam Park

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Ultrafast two-dimensional infrared (2DIR) spectroscopy was used to study H-bond exchange dynamics in aqueous NaPF6 solutions. Interestingly, there are two spectrally distinct hydrogen-bond (H-bond) configurations in aqueous NaPF6 solutions: water molecules that are H-bonded to PF 6- (ODA) or other water molecules (OD W). These two spectrally distinct subsets of water in aqueous NaPF6 solutions provide an opportunity to study the individual dynamics of water in two H-bond configurations as well as interconversion dynamics between them. Most significantly, we have successfully measured H-bond exchange dynamics between two spectrally distinct H-bond configurations in real time by ultrafast 2DIR spectroscopy. In aqueous 5.0 M NaPF6 solution, water molecules switch their H-bond partners from PF6- to water molecule (ODA → ODW) with a time constant of 12.0 ps and from water molecule to PF6- (ODW → ODA) with a time constant of 21.6 ps at room temperature. H-bond exchange dynamics in aqueous NaPF6 solution were found to be relatively slower than those in aqueous NaBF4 and NaClO4 solutions which were studied previously, which was attributed to the asymmetric potential energy curve for the H-bond exchange process based on the orientational jump mechanism.

Original languageEnglish
Pages (from-to)13604-13613
Number of pages10
JournalJournal of Physical Chemistry B
Volume117
Issue number43
DOIs
Publication statusPublished - 2013 Oct 31

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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