Water Structure on Mica Surfaces: Investigating the Effect of Cations

2019 ◽  
Author(s):  
Jiarun Zhou ◽  
Nurun Nahar Lata ◽  
Sapna Sarupria ◽  
will cantrell
Keyword(s):  
Divalent Cations ◽  
Water Structure ◽  
Ice Nucleation ◽  
Water Molecules ◽  
Interfacial Water ◽  
Ice Nucleation Protein ◽  
Naturally Occurring ◽  
Air Interface ◽  
Bulk Structure ◽  
Dynamics Simulations

We studied thin films of water at the mica-air interface using infrared spectroscopy and molecular dynamics simulations. We investigate the influence of ions on interfacial water by exchanging the naturally occurring K<sup>+</sup> ion with H<sup>+</sup>/Na<sup>+</sup>, Ca<sup>2+</sup>, and Mg<sup>2+</sup>. The experiments do not show a difference in the bulk structure (<i>i. e.</i> in the infrared spectra), but indicate that water is more strongly attracted to the Mg<sup>2+</sup> mica. The simulations reveal that the cation-water interactions significantly influence the microscopic arrangement of water on mica. Our results indicate that the divalent cations result in strong water-mica interactions, which leads to longer hydrogen bond lifetimes and larger hydrogen bonded clusters of interfacial water molecules. These results have implications for surface-mediated processes such as heterogeneous ice nucleation, protein assembly and catalysis.

Water Structure on Mica Surfaces: Investigating the Effect of Cations

2019 ◽  
Author(s):  
Jiarun Zhou ◽  
Nurun Nahar Lata ◽  
Sapna Sarupria ◽  
will cantrell
Keyword(s):  
Divalent Cations ◽  
Water Structure ◽  
Ice Nucleation ◽  
Water Molecules ◽  
Interfacial Water ◽  
Ice Nucleation Protein ◽  
Naturally Occurring ◽  
Air Interface ◽  
Bulk Structure ◽  
Dynamics Simulations

We studied thin films of water at the mica-air interface using infrared spectroscopy and molecular dynamics simulations. We investigate the influence of ions on interfacial water by exchanging the naturally occurring K<sup>+</sup> ion with H<sup>+</sup>/Na<sup>+</sup>, Ca<sup>2+</sup>, and Mg<sup>2+</sup>. The experiments do not show a difference in the bulk structure (<i>i. e.</i> in the infrared spectra), but indicate that water is more strongly attracted to the Mg<sup>2+</sup> mica. The simulations reveal that the cation-water interactions significantly influence the microscopic arrangement of water on mica. Our results indicate that the divalent cations result in strong water-mica interactions, which leads to longer hydrogen bond lifetimes and larger hydrogen bonded clusters of interfacial water molecules. These results have implications for surface-mediated processes such as heterogeneous ice nucleation, protein assembly and catalysis.

Molecular Dynamics Simulation of Quasi-Two-Dimensional Water Network on Ice Nucleation Protein

2011 ◽  
Author(s):  
Daisuke Murakami ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Water Clusters ◽  
Ice Nucleation ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Two Dimensional ◽  
Threshold Density ◽  
Ice Nucleation Protein ◽  
Network Of Hydrogen Bonds ◽  
Dynamics Simulations

An ice nucleation protein induces a phase transition from liquid water to ice in air. A specific hydrophilic surface of the protein may have an influence on the network of hydrogen bonds touching on the protein. However, microscopic characteristics of the ice nucleation protein and behavior of water molecules on it have not been clarified. So we carried out molecular dynamics simulations in various quasi-two-dimensional densities of water molecules on the ice nucleation protein. The percolation threshold of water clusters was confirmed. Comparing another hydrophilic protein, the threshold density in both cases had nearly the same value. But percolation probabilities and mean cluster sizes near the threshold were different between both cases. Those results implied that the threshold density was consistent with the conventional theory, but the forming of water clusters near the threshold was influenced by the hydrophilicity on the ice nucleation protein.

scholarly journals Icephobicity of Functionalized Graphene Surfaces

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Xiang-Xiong Zhang ◽  
Min Chen
Keyword(s):  
Molecular Dynamics ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Chloride Ions ◽  
Water Molecules ◽  
Sodium Ions ◽  
Functionalized Graphene ◽  
Functionalized Surfaces ◽  
The Difference ◽  
Dynamics Simulations

Manipulating the ice nucleation ability of liquid water by solid surface is of fundamental importance, especially in the design of icephobic surfaces. In this paper, the icephobicity of graphene surfaces functionalized by sodium ions, chloride ions, or methane molecules is investigated using molecular dynamics simulations. The icephobicity of the surface is evaluated by the freezing temperature. The freezing temperature on surface functionalized by methane molecules decreases at first and then increases as a function of the number groups, while the freezing temperature increases monotonically as a function of the number groups upon surfaces functionalized by sodium ions or chloride ions. The difference can be partially explained by the potential morphologies near the surfaces. Additionally, the validity of indicating the ice nucleation ability of water molecules using the number of six rings in the system is examined. Current study shows that the ice nucleation upon functionalized surfaces is inhibited when compared with smooth graphene substrate, which proves the feasibility of changing the icephobicity of the surfaces by functionalizing with certain ions or molecules.

scholarly journals Water Structure at the Interface of Alcohol Monolayers as Predicted by Computational Vibrational Sum-Frequency Generation Spectroscopy

2018 ◽  
Author(s):  
Daniel R. Moberg ◽  
Qin Li ◽  
Sandeep K. Reddy ◽  
Francesco Paesani
Keyword(s):  
Alkyl Chain ◽  
Force Fields ◽  
Water Structure ◽  
Sum Frequency Generation ◽  
Interfacial Water ◽  
Sum Frequency ◽  
Frequency Generation ◽  
Computational Spectroscopy ◽  
Dynamics Simulations ◽  
Alcohol Monolayers

<div> <div> <div> <p>In this study, we investigate the structure of water at the interface of three long-chain alcohol monolayers differing in alkyl chain length through molecular dynamics simulations combined with modeling of vibrational sum-frequency generation (vSFG) spectra. The effects of alkyl chain parity on interfacial water is examined through extensive analysis of structural properties, hydrogen bonding motifs, and spectral features. Besides providing molecular-level insights into the structure of interfacial water, this study also demonstrates that, by enabling direct comparisons with experimental vSFG spectra, computational spectroscopy may be used to test and validate force fields commonly used in biomolecular simulations. The results presented here can thus serve as benchmarks for both further investigations to characterize ice nucleation induced by alcohol monolayers and refinement of popular biomolecular force fields. </p> </div> </div> </div>

scholarly journals Surface charge-induced orientation of interfacial water suppresses heterogeneous ice nucleation on α-alumina (0001)

2017 ◽  
Author(s):  
Ahmed Abdelmonem ◽  
Ellen H. G. Backus ◽  
Nadine Hoffmann ◽  
M. Alejandra Sánchez ◽  
Jenée D. Cyran ◽  
...  
Keyword(s):  
Surface Charge ◽  
Atmospheric Aerosols ◽  
Molecular Level ◽  
Water Structure ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Low Ph ◽  
Cloud Formation ◽  
Interfacial Water ◽  
Heterogeneous Ice Nucleation

Abstract. Surface charge is one of the surface properties of atmospheric aerosols, which has been linked to heterogeneous ice-nucleation and hence cloud formation, microphysics and optical properties. Despite the importance of surface charge for ice nucleation, many questions remain on the molecular-level mechanisms at work. Here, we combine droplet freezing assay studies with vibrational sum frequency generation (SFG) spectroscopy to correlate interfacial water structure to surface nucleation strength. We study immersion freezing of aqueous solutions of various pHs on the atmospherically relevant aluminum oxide α-Al2O3 (0001) surface using an isolated droplet on the surface . The high pH solutions freeze at temperatures higher than that of the low pH solution while the neutral pH has the highest freezing temperature. On the molecular level, the SFG spectrum of the interfacial water changes substantially upon freezing. At all pHs, crystallization leads to a reduction of intensity of the 3400 cm−1 water resonance, while the 3200 cm−1 intensity drops for low pH but increases for neutral and high pHs. We find that charge-induced surface templating suppresses nucleation, irrespective of the sign of the surface charge. Heterogeneous nucleation is most efficient for the nominally neutral surface.

scholarly journals Determination and evaluation of the nonadditivity in wetting of molecularly heterogeneous surfaces

2019 ◽  
Vol 116 (51) ◽  
pp. 25516-25523 ◽  
Author(s):  
Zhi Luo ◽  
Anna Murello ◽  
David M. Wilkins ◽  
Filip Kovacik ◽  
Joachim Kohlbrecher ◽  
...  
Keyword(s):  
Water Structure ◽  
Work Of Adhesion ◽  
Effective Diameter ◽  
Interfacial Water ◽  
Sum Frequency ◽  
Wetting Properties ◽  
Molecular Arrangement ◽  
Starting Point ◽  
Folded Proteins ◽  
Dynamics Simulations

The interface between water and folded proteins is very complex. Proteins have “patchy” solvent-accessible areas composed of domains of varying hydrophobicity. The textbook understanding is that these domains contribute additively to interfacial properties (Cassie’s equation, CE). An ever-growing number of modeling papers question the validity of CE at molecular length scales, but there is no conclusive experiment to support this and no proposed new theoretical framework. Here, we study the wetting of model compounds with patchy surfaces differing solely in patchiness but not in composition. Were CE to be correct, these materials would have had the same solid–liquid work of adhesion (WSL) and time-averaged structure of interfacial water. We find considerable differences inWSL, and sum-frequency generation measurements of the interfacial water structure show distinctively different spectral features. Molecular-dynamics simulations of water on patchy surfaces capture the observed behaviors and point toward significant nonadditivity in water density and average orientation. They show that a description of the molecular arrangement on the surface is needed to predict its wetting properties. We propose a predictive model that considers, for every molecule, the contributions of its first-nearest neighbors as a descriptor to determine the wetting properties of the surface. The model is validated by measurements ofWSLin multiple solvents, where large differences are observed for solvents whose effective diameter is smaller than ∼6 Å. The experiments and theoretical model proposed here provide a starting point to develop a comprehensive understanding of complex biological interfaces as well as for the engineering of synthetic ones.

scholarly journals Surface-charge-induced orientation of interfacial water suppresses heterogeneous ice nucleation on <i>α</i>-alumina (0001)

2017 ◽  
Vol 17 (12) ◽  
pp. 7827-7837 ◽  
Author(s):  
Ahmed Abdelmonem ◽  
Ellen H. G. Backus ◽  
Nadine Hoffmann ◽  
M. Alejandra Sánchez ◽  
Jenée D. Cyran ◽  
...  
Keyword(s):  
Surface Charge ◽  
Atmospheric Aerosols ◽  
Molecular Level ◽  
Water Structure ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Low Ph ◽  
Cloud Formation ◽  
Interfacial Water ◽  
Heterogeneous Ice Nucleation

Abstract. Surface charge is one of the surface properties of atmospheric aerosols, which has been linked to heterogeneous ice nucleation and hence cloud formation, microphysics, and optical properties. Despite the importance of surface charge for ice nucleation, many questions remain on the molecular-level mechanisms at work. Here, we combine droplet-freezing assay studies with vibrational sum frequency generation (SFG) spectroscopy to correlate interfacial water structure to surface nucleation strength. We study immersion freezing of aqueous solutions of various pHs on the atmospherically relevant aluminum oxide α-Al2O3 (0001) surface using an isolated droplet on the surface. The high-pH solutions freeze at temperatures higher than that of the low-pH solution, while the neutral pH has the highest freezing temperature. On the molecular level, the SFG spectrum of the interfacial water changes substantially upon freezing. At all pHs, crystallization leads to a reduction of intensity of the 3400 cm−1 water resonance, while the 3200 cm−1 intensity drops for low pH but increases for neutral and high pHs. We find that charge-induced surface templating suppresses nucleation, irrespective of the sign of the surface charge. Heterogeneous nucleation is most efficient for the nominally neutral surface.

Liquid Water Confined in Cellulose with Variable Interfacial Hydrophilicity

2018 ◽  
Vol 232 (7-8) ◽  
pp. 989-1002 ◽  
Author(s):  
Tobias Watermann ◽  
Daniel Sebastiani
Keyword(s):  
Liquid Water ◽  
Smooth Surface ◽  
Water Structure ◽  
Bulk Water ◽  
Spatial Accessibility ◽  
Water Molecules ◽  
Crystal Water ◽  
Coordination Numbers ◽  
Interfacial Water Structure ◽  
Dynamics Simulations

Abstract We investigate liquid water confined within nanoscale cellulose slabs by means of molecular dynamics simulations. Depending on the construction of the cellulose–water interface, two different surface structures with distinct levels of hydrophilicity are exposed to the water. The different philicities are reflected in the response of the water phase to this geometric confinement, both in terms of the density profile and in the strength of the aqueous hydrogen bonding network. At the smooth surface cut along the (010) axis of the cellulose crystal, water shows typical properties of a hydrophilic confinement: the density shows fluctuations that disappear further away from the wall, the water molecules orient themselves and the coordination numbers increases at the interface. As a consequence, the water becomes “harder” at the interface, with a considerably increased local ordering. At the zigzag-shaped surface along the (111) axis, the degree of hydrophilicity is reduced, and only small effects can be seen: the density shows weak fluctuations, and the orientation of the water molecules is closer to that of bulk water than to the smooth surface. The local coordination numbers remains constant over the whole confinement. Our work shows that the nature of the exposed cellulose interface has a strong influence on how the structure of adjacent water is modified. The different ways of surface construction yield distinct degrees of hydrophilicity and spatial accessibility regarding the hydrogen bond network, resulting in a notably different interfacial water structure.

scholarly journals Heterogeneous ice nucleation correlates with bulk-like interfacial water

2019 ◽  
Vol 5 (4) ◽  
pp. eaat9825 ◽  
Author(s):  
Shuwang Wu ◽  
Zhiyuan He ◽  
Jinger Zang ◽  
Shenglin Jin ◽  
Zuowei Wang ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Bound Water ◽  
Ice Nucleation ◽  
Hydroxyl Group ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Interfacial Water ◽  
New Strategy ◽  
Group Density ◽  
Heterogeneous Ice Nucleation

Establishing a direct correlation between interfacial water and heterogeneous ice nucleation (HIN) is essential for understanding the mechanism of ice nucleation. Here, we study the HIN efficiency on polyvinyl alcohol (PVA) surfaces with different densities of hydroxyl groups. We find that the HIN efficiency increases with the decreasing hydroxyl group density. By explicitly considering that interfacial water molecules of PVA films consist of “tightly bound water,” “bound water,” and “bulk-like water,” we reveal that bulk-like water can be correlated directly to the HIN efficiency of surfaces. As the density of hydroxyl groups decreases, bulk-like water molecules can rearrange themselves with a reduced energy barrier into ice due to the diminishing constraint by the hydroxyl groups on the PVA surface. Our study not only provides a new strategy for experimentally controlling the HIN efficiency but also gives another perspective in understanding the mechanism of ice nucleation.

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