Hydrogen-Bond Relations for Surface OH Species

Kebede, Getachew; Mitev, Pavlin D.; Broqvist, Peter; Kullgren, Jolla; Hermansson, Kersti

doi:10.1021/acs.jpcc.7b10981

Cited by 9 publications

(18 citation statements)

References 58 publications

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“…The interaction energy is considered with respect to the parameters r O···H , θ Mol , and θ OH based on the Pearson correlation coefficient. It can be seen graphically (Figure S2) and numerically (Table ) that the interaction energy tends to depend on r O···H for all three liquids, as previously seen in X-ray diffraction experimental results and density functional theory based calculations. , The negative coefficient between interaction energy and r O···H for CLF signifies the local repulsive interactions between a CLF molecule and the hydroxyl groups of sapphire. Additionally, the low magnitude of the Pearson correlation of θ Mol with energy indicates the minimal influence of θ Mol on the energy.…”

Section: Resultssupporting

confidence: 74%

“…It can be seen graphically (Figure S2) and numerically (Table 2) that the interaction energy tends to depend on r O•••H for all three liquids, as previously seen in X-ray diffraction experimental results and density functional theory based calculations. 44,67 The negative coefficient between interaction energy and r O•••H for CLF signifies the local repulsive interactions between a CLF molecule and the hydroxyl groups of sapphire. Additionally, the low magnitude 1.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Despite the limitation, the distributions of geometric parameters can act as vital tools to understand the broadness in the interaction energy profiles. Additionally, the geometric parameters correlate with enthalpy of interaction and therefore spectral shifts, − which can be used to reveal the origin of broadness in the vibrational spectra.…”

Section: Introductionmentioning

confidence: 99%

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Interaction Geometry Causes Spectral Line-Shape Broadening at the Solid/Liquid Interface

et al. 2019

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Line shape broadness in vibrational spectra is usually associated with structural heterogeneity of the surrounding environment. At the solid/liquid interface, surface-sensitive sum frequency generation spectroscopy (SFG) has shown a variety of distributions of the vibrational frequency for sapphire surface hydroxyl groups in contact with several liquids. Even though the broadness in SFG spectra could be associated with the surface heterogeneity and diverse interfacial interactions, the origin remains elusive in experiments. To better understand the physical picture of interfacial interactions, and hence broadness, we perform SFG along with molecular dynamics (MD) simulations of liquid molecules in contact with sapphire. In the SFG spectra, line-shape broadness of the sapphire hydroxyl group vibrational frequency increases in the following order: chloroform, acetone, and dimethyl sulfoxide. The broadness in the interaction energy distributions calculated from the MD simulations for the molecules interacting with surface hydroxyl groups follows the same order. MD simulations show that liquid molecules are seen to interact locally with multiple sapphire hydroxyl groups. The number of interactions depends on the location of a molecule with respect to the surface hydroxyl groups, which relate to the packing of individual molecules on surface sites. Regardless of the number of hydroxyl groups that a molecule interacts with, the strength of the strongest interaction remains similar. However, neighboring hydroxyl groups interact with the same molecule with weaker energies, creating broadness in the interaction energy distribution for the strongly interacting (acetone and dimethyl sulfoxide) species. The energy distribution profiles correlate well with the experimental SFG spectra, highlighting the ability to interpret spectroscopic features with the physical insights gained from MD simulations.

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Section: Resultssupporting

confidence: 74%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interaction Geometry Causes Spectral Line-Shape Broadening at the Solid/Liquid Interface

et al. 2019

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“…Thus, in order to compare the experimental surface concentrations from Singla et al and that from simulations, a simulation must probe the surface similarly. As the acid−base interaction strength depends on the distance between the interacting molecules, 56 calculating the surface concentrations in the simulations using a radial-cut instead of a Z-cut would be expected to better reproduce the surface concentration from SFG experiments, where the radial distance is measured from the sapphire hydrogen.…”

Section: Resultsmentioning

confidence: 99%

Atomistic Insights into Hydrogen-Bonding-Driven Competitive Adsorption of Acetone–Chloroform Binary Mixtures

et al. 2019

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The competitive adsorption of molecules on a surface has both beneficial and detrimental effects for technological applications, such as chromatography (material separation) and protein adsorption on medical implants. A comprehensive understanding of adsorption can aid in the design of surfaces with desired functional properties. Molecular dynamics (MD) simulations serve as a direct approach to quantify interfacial behavior. In this study, we use MD simulations to gain insights into the adsorption of acetone−chloroform mixtures on a solid sapphire substrate. Acetone segregates preferentially to the sapphire surface because of hydrogen bonding between the oxygen atom of the acetone molecules and the sapphire surface hydroxyl groups. Both acetone and chloroform possess two probable orientations next to sapphire. Orientation analysis reveals that the presence of chloroform alters the way acetone interacts with the surface, and vice versa. Two analysis methods were developed and utilized to calculate the surface segregation: radial-cut and Z-cut. By comparing the results from the two MD simulation analysis methods, we gain insights into hydrogen-bonding-driven surface segregation and illustrate challenges in defining the surface phase. The surface segregation calculated using the radial-cut method matches with the Defay−Prigogine adsorption model with the differences in interfacial energies of individual components calculated using the Badger−Bauer and Dupre−Fowkes formalism. In addition, the surface segregation from the radial-cut method is found to correlate well with previously reported sum-frequency generation spectroscopy results. The current study paves the way for the overall understanding of adsorption, which can help in designing new surfaces for controlling adsorption.

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“…This computational approach has previously been used by us to calculate OH frequencies of water molecules and hydroxide ions in crystals 16,27,28 and on surfaces 29 as well as in liquid water 30 and ionic aqueous solutions. 31…”

Section: Calculation Of Anharmonic Oh Frequenciesmentioning

confidence: 99%

Red-shifting and blue-shifting OH groups on metal oxide surfaces – towards a unified picture

Kebede

Mitev

Briels

et al. 2018

Phys. Chem. Chem. Phys.

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We analyse the OH vibrational signatures of 56 structurally unique water molecules and 34 structurally unique hydroxide ions in thin water films on MgO(001) and CaO(001), using DFT-generated anharmonic potential energy surfaces. We find that the OH stretching frequencies of intact water molecules on the surface are always downshifted with respect to the gas-phase species while the OH- groups are either upshifted or downshifted. Despite these differences, the main characteristics of the frequency shifts for all three types of surface OH groups (OHw, OsH and OHf) can be accounted for by one unified expression involving the in situ electric field from the surrounding environment, and the gas-phase molecular properties of the vibrating species (H2O or OH-). The origin behind the different red- and blueshift behaviour can be traced back to the fact that the molecular dipole moment of a gas-phase water molecule increases when an OH bond is stretched, but the opposite is true for the hydroxide ion. We propose that familiarity with the relations presented here will help surface scientists in the interpretation of vibrational OH spectra for thin water films on ionic crystal surfaces.

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Hydrogen-Bond Relations for Surface OH Species

Cited by 9 publications

References 58 publications

Interaction Geometry Causes Spectral Line-Shape Broadening at the Solid/Liquid Interface

Interaction Geometry Causes Spectral Line-Shape Broadening at the Solid/Liquid Interface

Atomistic Insights into Hydrogen-Bonding-Driven Competitive Adsorption of Acetone–Chloroform Binary Mixtures

Red-shifting and blue-shifting OH groups on metal oxide surfaces – towards a unified picture

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