Quantitative consistency between the intensity and phase-resolved sum frequency generation vibrational spectra of the air/neat-water interface

Abstract

We report the first sub-1 cm−1 resolution high-resolution broadband sum-frequency generation vibrational spectroscopy ssp intensity spectra of the air/neat-water interface across the 1500–3900 cm−1 spectral range. Utilizing a direct fitting approach, we reconstruct the phase-resolved spectra that quantitatively agree with previously reported phase-resolved measurements while revealing additional spectral features and phase information. This combined analysis advances molecular-level understanding of water’s vibrational dynamics and orientation at the interface. Our results establish a robust framework linking intensity and phase-resolved SFG data, providing a foundation for future polarization and experimental configuration dependent studies aimed at resolving ongoing debates regarding interfacial water structure.