Communication: Interfacial water structure revealed by ultrafast two-dimensional surface vibrational spectroscopy

Zhang, Zhen; Piątkowski, Łukasz; Bakker, Huib J.; Bonn, Mischa

doi:10.1063/1.3605657

Cited by 52 publications

(62 citation statements)

References 31 publications

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“…They argued that two different water sub‐ensembles (that is, weakly and strongly hydrogen‐bonded water species), which show distinct vibrational dynamics, exist at the lipid interfaces17a,17b irrespective of the chemical nature of the head group 17c. In the present heterodyne 2D VSFG study on HOD in D 2 O, we did not find any spectral responses that indicate such distinct types (two varieties) of interfacial water at either of the lipid interfaces.…”

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confidence: 72%

Femtosecond Hydrogen Bond Dynamics of Bulk‐like and Bound Water at Positively and Negatively Charged Lipid Interfaces Revealed by 2D HD‐VSFG Spectroscopy

et al. 2016

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Interfacial water in the vicinity of lipids plays an important role in many biological processes, such as drug delivery, ion transportation, and lipid fusion. Hence, molecular‐level elucidation of the properties of water at lipid interfaces is of the utmost importance. We report the two‐dimensional heterodyne‐detected vibrational sum frequency generation (2D HD‐VSFG) study of the OH stretch of HOD at charged lipid interfaces, which shows that the hydrogen bond dynamics of interfacial water differ drastically, depending on the lipids. The data indicate that the spectral diffusion of the OH stretch at a positively charged lipid interface is dominated by the ultrafast (<∼100 fs) component, followed by the minor sub‐picosecond slow dynamics, while the dynamics at a negatively charged lipid interface exhibit sub‐picosecond dynamics almost exclusively, implying that fast hydrogen bond fluctuation is prohibited. These results reveal that the ultrafast hydrogen bond dynamics at the positively charged lipid–water interface are attributable to the bulk‐like property of interfacial water, whereas the slow dynamics at the negatively charged lipid interface are due to bound water, which is hydrogen‐bonded to the hydrophilic head group.

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confidence: 72%

Femtosecond Hydrogen Bond Dynamics of Bulk‐like and Bound Water at Positively and Negatively Charged Lipid Interfaces Revealed by 2D HD‐VSFG Spectroscopy

et al. 2016

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“…Another important piece of the methodology is heterodyne detection (20)(21)(22)(23)(24). Recently, landmark 2D SFG spectra were reported (25,26). Those experiments, along with related pump-probe SFG experiments (27)(28)(29), proved that the signal strengths are sufficient for performing higherorder nonlinear spectroscopy at interfaces.…”

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confidence: 96%

Adding a dimension to the infrared spectra of interfaces using heterodyne detected 2D sum-frequency generation (HD 2D SFG) spectroscopy

Xiong

Laaser

Mehlenbacher

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

169

232

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In the last ten years, two-dimensional infrared spectroscopy has become an important technique for studying molecular structures and dynamics. We report the implementation of heterodyne detected two-dimensional sum-frequency generation (HD 2D SFG) spectroscopy, which is the analog of 2D infrared (2D IR) spectroscopy, but is selective to noncentrosymmetric systems such as interfaces. We implement the technique using mid-IR pulse shaping, which enables rapid scanning, phase cycling, and automatic phasing. Absorptive spectra are obtained, that have the highest frequency resolution possible, from which we extract the rephasing and nonrephasing signals that are sometimes preferred. Using this technique, we measure the vibrational mode of CO adsorbed on a polycrystalline Pt surface. The 2D spectrum reveals a significant inhomogenous contribution to the spectral line shape, which is quantified by simulations. This observation indicates that the surface conformation and environment of CO molecules is more complicated than the simple "atop" configuration assumed in previous work. Our method can be straightforwardly incorporated into many existing SFG spectrometers. The technique enables one to quantify inhomogeneity, vibrational couplings, spectral diffusion, chemical exchange, and many other properties analogous to 2D IR spectroscopy, but specifically for interfaces. multidimensional spectroscopy | vibrational spectroscopy | surface-sensitive | Pt catalysis | CO monolayer M olecular spectroscopies are some of the best tools for studying structures and dynamics. Two particularly useful variants are sum-frequency generation (SFG) and two-dimensional infrared (2D IR) spectroscopy. SFG spectroscopy provides a vibrational spectrum of molecular systems that lack an inversion center (1), and so has become a valuable tool for probing interfaces because no signal arises from the bulk. SFG spectroscopy has helped reveal the surface structure of liquids, characterize the surfaces of materials, and probe membrane proteins, to name only a few applications (2-5). 2D IR spectroscopy is also a vibrational spectroscopy, although not interface specific. 2D IR spectroscopy spreads the infrared spectrum into a second coordinate so that coupled vibrational modes are correlated by cross peaks, vibrational dynamics quantified by 2D line shapes, and energy transfer or chemical exchange revealed from peak intensities (6-8), in addition to many other capabilities not possible with linear one-dimensional (1D) vibrational spectroscopies like SFG spectroscopy. 2D IR spectroscopy is now being used to study protein structure and dynamics, solvent dynamics, charge transfer in semiconductors, and many other processes (9-12). These two techniques might be considered the core technologies of modern infrared spectroscopy.In this article, we combine the surface sensitivity of SFG spectroscopy with the multidimensional capabilities of 2D IR spectroscopy in a technique that we call heterodyne detected (HD) 2D SFG spectroscopy. With this technique, one obtain...

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“…Rather, we expect there to be a continuous distribution of hydrogen bond strengths, both between water molecules themselves and between water molecules and lipids/proteins. Indeed, lifetime measurements of the O-H stretch vibration of interfacial water [24] and 2-dimensional surface sum-frequency generation spectroscopy [22,23] have revealed a continuous heterogeneity of water molecules at the water-air interface and have evidenced the presence of an additional type of water at the water-lipid interface, presumably water that is strongly hydrogen-bonded to the lipid head group.…”

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confidence: 99%

“…2 a The anharmonic interaction between two degenerate vibrational levels, in this case the fundamental transition of the OH/OD stretching mode and the overtone of the OH/OD bending mode, causes a splitting of the energy levels into symmetric and asymmetric combination modes. b The broad, inhomogeneously broadened [22,23] water O-D or O-H stretch mode density of vibrational states (DOS) couples strongly to the overtone of the bending mode. The bend overtone couples most strongly to those modes within the quasicontinuum of stretch modes that have the same frequency vibrational states is now contained in the one resonance, rather than being split into two.…”

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confidence: 99%

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No Ice-Like Water at Aqueous Biological Interfaces

et al. 2012

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The surface vibrational spectrum of water at biological interfaces is often interpreted as having ‘ice-like’ and ‘liquid-like’ components. Here we show that the vibrational spectrum of water at both water–lipid and water–protein interfaces greatly simplifies upon H/D isotopic dilution, which is inconsistent with the presence of ‘ice-like’ structures. The changes in the spectra as a function of isotope content can be explained by intramolecular coupling between bend and stretch vibrations of the water molecules.

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Communication: Interfacial water structure revealed by ultrafast two-dimensional surface vibrational spectroscopy

Cited by 52 publications

References 31 publications

Femtosecond Hydrogen Bond Dynamics of Bulk‐like and Bound Water at Positively and Negatively Charged Lipid Interfaces Revealed by 2D HD‐VSFG Spectroscopy

Femtosecond Hydrogen Bond Dynamics of Bulk‐like and Bound Water at Positively and Negatively Charged Lipid Interfaces Revealed by 2D HD‐VSFG Spectroscopy

Adding a dimension to the infrared spectra of interfaces using heterodyne detected 2D sum-frequency generation (HD 2D SFG) spectroscopy

No Ice-Like Water at Aqueous Biological Interfaces

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