Interpreting Vibrational Sum-Frequency Spectra of Sulfur Dioxide at the Air/Water Interface: A Comprehensive Molecular Dynamics Study

<div> <div> <div> <p>The temperature dependence of the vibrational sum-frequency generation (vSFG) spectra of the the air/water interface is investigated using many-body molecular dynamics (MB-MD) simulations performed with the MB-pol potential energy function. The total vSFG spectra calculated for different polarization combinations are then analyzed in terms of molecular auto-correlation and cross-correlation contributions. To provide molecular-level insights into interfacial hydrogen-bonding topologies, which give rise to specific spectroscopic features, the vSFG spectra are further investigated by separating contributions associated with water molecules donating 0, 1, or 2 hydrogen bonds to neighboring water molecules. This analysis suggests that the low frequency shoulder of the free OH peak which appears at ∼3600 cm−1 is primarily due to intermolecular couplings between both singly and doubly hydrogen-bonded molecules. </p> </div> </div> </div>

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Sum Frequency Generation Spectroscopic Studies on Phase Transitions of Phospholipid Monolayers Containing Poly(ethylene oxide) Lipids at the Air−Water Interface

The Journal of Physical Chemistry B ◽

10.1021/jp064179x ◽

2007 ◽

Vol 111 (7) ◽

pp. 1693-1700 ◽

Cited By ~ 23

Author(s):

C. Ohe ◽

Y. Goto ◽

M. Noi ◽

M. Arai ◽

H. Kamijo ◽

...

Keyword(s):

Phase Transitions ◽

Ethylene Oxide ◽

Spectroscopic Studies ◽

Sum Frequency Generation ◽

Water Interface ◽

Sum Frequency ◽

Phospholipid Monolayers ◽

Air Water Interface ◽

Poly Ethylene Oxide ◽

Poly Ethylene

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Spectroscopic BIL-SFG Invariance Hides the Chaotropic Effect of Protons at the Air-Water Interface

Atmosphere ◽

10.3390/atmos9100396 ◽

2018 ◽

Vol 9 (10) ◽

pp. 396 ◽

Cited By ~ 7

Author(s):

Simone Pezzotti ◽

Marie-Pierre Gaigeot

Keyword(s):

Water Structure ◽

Md Simulations ◽

Interfacial Structure ◽

Water Interface ◽

Sum Frequency ◽

Hydronium Ion ◽

Sum Frequency Generation Spectroscopy ◽

Air Water Interface ◽

Ph Conditions ◽

Shed Light

The knowledge of the water structure at the interface with the air in acidic pH conditions is of utmost importance for chemistry in the atmosphere. We shed light on the acidic air-water (AW) interfacial structure by DFT-MD simulations of the interface containing one hydronium ion coupled with theoretical SFG (Sum Frequency Generation) spectroscopy. The interpretation of SFG spectra at charged interfaces requires a deconvolution of the signal into BIL (Binding Interfacial Layer) and DL (Diffuse Layer) SFG contributions, which is achieved here, and hence reveals that even though H 3 O + has a chaotropic effect on the BIL water structure (by weakening the 2D-HBond-Network observed at the neat air-water interface) it has no direct probing in SFG spectroscopy. The changes observed experimentally in the SFG of the acidic AW interface from the SFG at the neat AW are shown here to be solely due to the DL-SFG contribution to the spectroscopy. Such BIL-SFG and DL-SFG deconvolution rationalizes the experimental SFG data in the literature, while the hydronium chaotropic effect on the water 2D-HBond-Network in the BIL can be put in perspective of the decrease in surface tension at acidic AW interfaces.

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