Time Correlation Function Modeling of Third-Order Sum Frequency Vibrational Spectroscopy of a Charged Surface/Water...

Area of Science:

• Interface science
• Spectroscopy
• Computational chemistry

Background:

• Sum frequency vibrational spectroscopy (SFVS) is an interface-specific technique.
• Charged interfaces exhibit both second-order (enhanced) and third-order (static-field-induced) SFVS signals.
• Separating these contributions at a molecular level is challenging.

Purpose of the Study:

• To develop and apply a molecular dynamics (MD)-based theory for calculating third-order contributions to SFVS spectra at charged interfaces.
• To investigate the spectral features of an idealized silica/water interface.
• To compare computational results with experimental data for water at fused quartz.

Main Methods:

• Utilized a novel MD-based theory to calculate third-order SFVS contributions.
• Developed a hyperpolarizability model for water.
• Applied these methods to an abstracted silica/water interface model.

Main Results:

• Successfully calculated third-order contributions to SFVS spectra.
• Identified general spectral features for the silica/water interface.
• Computational results showed good agreement with experimental data for water at fused quartz.

Conclusions:

• The developed MD-based theory provides a direct method for calculating third-order SFVS contributions at charged interfaces.
• The study highlights general spectral characteristics applicable to silica/water systems.
• This approach advances the molecular-level understanding of interfacial phenomena through SFVS.