A time correlation function (TCF) description of vibrational sum-frequency generation (vSFG) spectroscopy was applied to theoretically describing the spectroscopy of the ambient water/vapor interface. The theoretical spectra compare favorably in shape and relative magnitude to extant experimental results in the O-H stretching region of water for all polarization geometries. The intermolecular spectrum of bulk water shows relatively little structure. However, the interfacial spectra for polarizations that are sensitive to dipole derivatives normal to the interface SSP and PPP and show a well-defined intermolecular mode at 875 cm−1 that is comparable in intensity to the rest of the intermolecular structure. Using instantaneous normal mode methods, the resonance is shown to be due to a wagging mode localized on a single water molecule, almost parallel to the interface, with two hydrogens displaced normal to the interface, and the oxygen anchored in the interface. We have also discussed the origin of another intermolecular mode at 95 cm−1 for the SSP and PPP spectra, and at 220 cm−1 for the SPS spectra. These resonances are due to hindered translations perpendicular to the interface for the SSP and PPP spectra, and translations parallel to the interface for the SPS spectra. Further, by examining the real and imaginary parts of the SFG signal, several resonances are shown to be due to a single spectroscopic species while the “donor” O-H region is shown to consist of three distinct species. These findings are consistent with recent experimental findings.

Theoretical description of the polarization dependence of vibrational sum frequency generation spectroscopy at the water/vapor interface

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.