Computational analysis of interfacial sum frequency generation spectrosopy

COMP 68

Akihiro Morita and Tatsuya Ishiyama. Department of Computational Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, 444-8585, Japan
While vibrational sum frequency generation (SFG) spectroscopy yields rich microscopic information on interfacial structure, interpretation of experimental spectra is often not straightforward. In this talk we summarize our recent progress on theoretical analysis of SFG spectroscopy, using ab initio molecular modeling and molecular dynamics simulation, and application to electrolyte aqueous solutions. The present analysis revealed a crucial role of intermolecular vibrational correlation, which significantly distorts the general relationship χ~N<β> between macroscopic susceptibility χ and molecular hyperpolarizability β. Experimental SFG spectra of different polarization combinations are consistently eludicated from the molecular dynamics results of electrolyte solutions, including NaCl, NaI, HCl and HI, which show quite different local structures at the interfaces.