Surface structure of sulfuric acid solution relevant to sulfate aerosol: Molecular dynamics simulation combined with sum frequency generation measurement

Tatsuya Ishiyama, Akihiro Morita, Takayuki Miyamae

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Surface structure of aqueous sulfuric acid solution at a typical atmospheric concentration (0.2x, x: mole fraction) is investigated by close collaboration of molecular dynamics (MD) simulation and sum frequency generation (SFG) measurement. The SFG spectra of both O-H and S-O stretching vibrations are provided with different sets of polarization combination. These sets of experimental spectra are consistently elucidated by the MD calculations. In modeling the surface structure, there exists a major uncertainty about local ion composition at the surface region. To address this uncertainty, we performed MD simulations with various assumptions on the local dissociation constants of sulfuric acid, and searched for the condition to be consistent with the experimental spectra. We have thereby concluded that the first acid dissociation of sulfuric acid is almost complete at the surface, while the second dissociation is more strongly suppressed than in the bulk liquid. The present MD simulation elucidates the ion distribution and molecular orientation at the sulfuric acid solution surface, and also the concentration dependence of the SFG spectrum.

Original languageEnglish
Pages (from-to)20965-20973
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume13
Issue number47
DOIs
Publication statusPublished - 2011 Dec 21

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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