(Figure Presented) Phase-sensitive sum-frequency vibrational spectroscopy (PS-SFVS) has been used to probe the isotopically diluted water/vapor interfaces in the spectral regions of OD (2200-2800 cm -1) and OH (3000-3800 cm -1) stretches. The experimentally measured Im X S (2) spectra, where X S (2) is the surface nonlinear susceptibility, permit direct characterization of resonances of the interfaces. The X S (2) spectrum of the HDO/vapor interface that is intrinsically simpler to analyze can be deduced from the result of isotopic dilution. It exhibits in the bonded-OH region a broad band comprising two parts with opposite signs, in contrast to those deduced earlier from fitting of the |X S (2)| 2 spectra and those calculated by MD simulation, but consistent with that obtained for the H 2O/vapor interface.
传山 田;元壤 沈
Journal of the American Chemical Society