Comparing vibrational sum frequency generation responses at fused silica and fluorite/liquid ethanol interfaces

Hou, Jian; Zhang, Xianyi; Lu, Zhou

doi:10.1016/j.chemphys.2020.110814

Cited by 3 publications

(5 citation statements)

References 79 publications

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“…stretching mode. 33 For the interface of the water−ethanol mixtures, the 2876 cm −1 Fermi resonance and the 2924 cm −1 symmetric C−H stretching mode of the CH 3 group govern the SFG spectra in the C−H range, 36 while the 2970 cm −1 antisymmetric C−H stretching mode and the C−H stretching mode of the CH 2 groups are weakin line with a previous study. 20 At the interface of the aqueous binary mixture of formic acid with air, a single peak is observed at 2930 cm −1 , which arises from the C−H stretching mode of formic acid.…”

Section: IIsupporting

confidence: 87%

“…The SFG spectra at the air–aqueous binary mixture of the methanol interface show peaks at 2840 and 2960 cm –1 and a shoulder at 2930 cm –1 , which are assigned to the symmetric C–H stretching mode, the antisymmetric C–H stretching mode, and the Fermi resonance of the C–H stretching and C–H bending modes, respectively. − Despite earlier assignments to the Fermi resonance, a recent study provides evidence for the ∼2960 cm –1 band to be due to the antisymmetric CH 3 stretching mode . For the interface of the water–ethanol mixtures, the 2876 cm –1 Fermi resonance and the 2924 cm –1 symmetric C–H stretching mode of the CH 3 group govern the SFG spectra in the C–H range, while the 2970 cm –1 antisymmetric C–H stretching mode and the C–H stretching mode of the CH 2 groups are weakin line with a previous study . At the interface of the aqueous binary mixture of formic acid with air, a single peak is observed at 2930 cm –1 , which arises from the C–H stretching mode of formic acid .…”

Section: Results and Discussionmentioning

confidence: 99%

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Interfacial Water Structure of Binary Liquid Mixtures Reflects Nonideal Behavior

Seki

et al. 2021

J. Phys. Chem. B

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The evaporation of molecules from water–organic solute binary mixtures is key for both atmospheric and industrial processes such as aerosol formation and distillation. Deviations from ideal evaporation energetics can be assigned to intermolecular interactions in solution, yet evaporation occurs from the interface, and the poorly understood interfacial, rather than the bulk, structure of binary mixtures affects evaporation kinetics. Here we determine the interfacial structure of nonideal binary mixtures of water with methanol, ethanol, and formic acid, by combining surface-specific vibrational spectroscopy with molecular dynamics simulations. We find that the free, dangling OH groups at the interfaces of these differently behaving nonideal mixtures are essentially indistinguishable. In contrast, the ordering of hydrogen-bonded interfacial water molecules differs substantially at these three interfaces. Specifically, the interfacial water molecules become more disordered (ordered) in mixtures with methanol and ethanol (formic acid), showing higher (lower) vapor pressure than that predicted by Raoult’s law.

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Section: IIsupporting

confidence: 87%

Section: Results and Discussionmentioning

confidence: 99%

Interfacial Water Structure of Binary Liquid Mixtures Reflects Nonideal Behavior

Seki

et al. 2021

J. Phys. Chem. B

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“…The Fermi resonance coupling coefficient quantifies the coupling strength of two nearly degenerate states. Hou et al have applied this model to support their results that the Fermi resonance mode is more suppressed at the SiO 2 /CH 3 CD 2 OH ( W = 25 ± 2 cm –1 ) interface than at the CaF 2 /CH 3 CD 2 OH interface ( W = 30 ± 1 cm –1 ) Figure c displays our calculated Fermi resonance coupling coefficients plotted as a function of the increasing MeOH mole fraction for MeOH/MeCN- d 3 mixtures.…”

supporting

confidence: 63%

“…Recent reports have shown that the intermolecular interactions of neighboring molecules at the interface may be quantified by the SFG intensity ratio of the Fermi resonance and the methyl symmetric stretch. − For instance, Tian et al have established a method to deduce the total intermolecular interactions of phospholipids in a monolayer by relating it to the second-order Fermi resonant signal . A relationship between the intensity ratio, R , of the Fermi resonant mode and the methyl stretching mode established an effective method to relate increasing neighboring phospholipid interactions to the Fermi coupling strength with increasing surface pressure.…”

mentioning

confidence: 99%

“…To further deduce the Fermi resonance coupling effect observed at an interface for MeOH/MeCN- d 3 , we use the well-established two-level model to help quantify the effects of varying the methanol concentration on the Fermi resonance coupling coefficient, W . ,− The theory for the model has been described in previous reports for liquid methanol, ,, and it is summarized in the Supporting Information along with the calculated W for various mole fractions using the higher frequency (first sublayer) r + and r + FR values from two Lorentzian functions listed in Table S1. The Fermi resonance coupling coefficient quantifies the coupling strength of two nearly degenerate states.…”

mentioning

confidence: 99%

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Intermolecular Interactions at the Silica–Liquid Interface Modulate the Fermi Resonance Coupling in Surface Methanol

Bui

Colón

Velarde

2021

J. Phys. Chem. Lett.

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The buried solid/liquid interface between hydrophilic fused silica and binary solvent mixtures of acetonitrile (MeCN) and methanol (MeOH) was studied with vibrational sum-frequency generation (vSFG) spectroscopy. Our data showed that at high relative concentrations of methanol, the Fermi resonance peak in the vSFG spectrum is greatly suppressed, and it progressively gains intensity as methanol is diluted with perdeuterated acetonitrile. This phenomenon is quantified by the Fermi resonance coupling coefficient, W, extracted using a two-level model, as well as the experimental intensity ratio, R, of the methyl Fermi resonance band to that of the symmetric stretch. At a 1.0 MeOH mole fraction, W and R values were 10 ± 10 cm–1 and 0.01 ± 0.02, respectively, whereas at a 0.1 mole fraction, W and R increased to 46 ± 4 cm–1 and 0.43 ± 0.16, respectively. This indicates that solvation with acetonitrile effectively tunes the Fermi coupling of methanol vibrations at the silica/liquid interface.

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Sum frequency spectroscopy studies on cell membrane fusion induced by divalent cations

Han

Sun

Wang

et al. 2022

Chinese Journal of Chemical Physics

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Cell membrane fusion is a fundamental biological process involved in a number of cellular living functions. Regarding this, divalent cations can induce fusion of the lipid bilayers through binding and bridging of divalent cations to the charged lipids, thus leading to the cell membrane fusion. How-ever, the elaborate mechanism of cell membrane fusion induced by divalent cations is still needed to be elucidated. Here, surface/interface sensitive sum frequency generation vibrational spectroscopy (SFG-VS) and dynamic light scattering (DLS) were applied in this research to study the responses of phospholipid monolayer to the exposure of divalent metal ions i.e. Ca2+ and Mg2+. According to the particle size distribution results measured by DLS experiments, it was found that Ca2+ could induce inter-vesicular fusion while Mg2+ could not. An octadecyltrichlorosilane self-assembled monolayer (OTS SAM)-lipid monolayer system was designed to model the cell membrane for the SFG-VS experiment. Ca2+ could interact with the lipid PO2− head groups more strongly, resulting in cell membrane fusion more easily, in comparison with Mg2+. No specific interaction between the two metal cations and the C=O groups was observed. However, the C=O orientations changed more after Ca2+-PO2− binding than Mg2+ mediation on lipid monolayer. Meanwhile, Ca2+ could induce dehydration of the lipids (which should be related to the strong Ca2+-PO2− interaction), leading to the reduced hindrance for cell membrane fusion.

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Comparing vibrational sum frequency generation responses at fused silica and fluorite/liquid ethanol interfaces

Cited by 3 publications

References 79 publications

Interfacial Water Structure of Binary Liquid Mixtures Reflects Nonideal Behavior

Interfacial Water Structure of Binary Liquid Mixtures Reflects Nonideal Behavior

Intermolecular Interactions at the Silica–Liquid Interface Modulate the Fermi Resonance Coupling in Surface Methanol

Sum frequency spectroscopy studies on cell membrane fusion induced by divalent cations

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