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Daub CD, Kurtén T. Effect of an Electric Field on the Structure and Stability of Atmospheric Clusters. J Phys Chem A 2024; 128:646-655. [PMID: 38217515 DOI: 10.1021/acs.jpca.3c07260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2024]
Abstract
We study the influence of an applied electric field on the structure and stability of some common bimolecular clusters that are found in the atmosphere. These clusters play an important role in new particle formation (NPF). For low values of the electric field (i.e., |E| ≤ 0.01 V Å-1), we demonstrate that the field response of the clusters can be predicted from simply calculating the dipole moment of the cluster and the dipole moments of the constituent molecules and that the influence on the association energy of the cluster is minimal (i.e., <0.5 kcal mol-1). For higher field strengths |E| > 0.2 V Å-1, there can be more dramatic effects on both structure and energetics, as the induced dipole, charge transfer, and geometric distortion play a larger role. Although such large fields are not very relevant in the atmosphere, they do exist in some situations of experimental interest, such as near interfaces and in intense laser fields.
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Affiliation(s)
| | - Theo Kurtén
- Department of Chemistry, University of Helsinki, P.O. Box 55, Helsinki 00014, Finland
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2
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Hantal G, Klíma M, McFegan L, Kolafa J, Jedlovszky P. Does the Sign of Charge Affect the Surface Affinity of Simple Ions? J Phys Chem B 2023. [PMID: 37399285 DOI: 10.1021/acs.jpcb.3c02641] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
The role the charge sign of simple ions plays in determining their surface affinity in aqueous solutions is investigated by computer simulation methods. For this purpose, the free surface of aqueous solutions of fictitious salts is simulated at finite concentration both with nonpolarizable point-charge and polarizable Gaussian-charge potential models. The salts consist of monovalent cations and anions that are, apart from the sign of their charge, identical to each other. In particular, we consider the small Na+ and the large I- ions together with their charge-inverted counterparts. In an attempt to avoid the interference even between the behavior of cations and anions, we also simulate systems containing only one of the above ions, and determine the free energy profile of these ions across the liquid-vapor interface of water at infinite dilution by potential of mean force (PMF) calculations. The obtained results reveal that, in the case of small ions, the anion is hydrated considerably stronger than the cation due to the close approach of water H atoms, bearing a positive fractional charge. As a consequence, the surface affinity of a small anion is even smaller than that of its cationic counterpart. However, considering that small ions are effectively repelled from the water surface, the importance of this difference is negligible. Further, a change in the hydration energy trends of the two oppositely charged ions is observed with their increasing size. This change is largely attributed to the fact that, with increasing ion size, the factor of 2 in the magnitude of the fractional charge of the closely approaching water atoms (i.e., O around cations and H around anions) outweighs the closer approach of the H than the O atom in the hydration energy. Thus, for large ions, being already surface active themselves, the surface affinity of the anion is larger than that of its positively charged counterpart. Further, such a difference is seen even in the case when the sign of the surface potential favors the adsorption of cations.
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Affiliation(s)
- György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria
| | - Martin Klíma
- Department of Physical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic
| | - Louisa McFegan
- Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | - Jiří Kolafa
- Department of Physical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 6, H-3300 Eger, Hungary
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3
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McFegan L, Juhász Á, Márton P, Hórvölgyi Z, Jedlovszky-Hajdu A, Hantal G, Jedlovszky P. Surface Affinity of Tetramethylammonium Iodide in Aqueous Solutions: A Combined Experimental and Computer Simulation Study. J Phys Chem B 2023. [PMID: 37276239 DOI: 10.1021/acs.jpcb.3c01370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The surface affinity of tetramethylammonium iodide (TMAI) in aqueous solutions is investigated by surface tension measurements and molecular dynamics computer simulations. Experiments, performed in the entire composition range of solubility using the pendant drop method with two different setups, clearly reveal that TMAI is a weakly capillary active salt. Computer simulations performed with the AMBER force field reproduce the experimental data very well, while two other major force fields (i.e., CHARMM and OPLS) can still reproduce the experimental trend qualitatively; however, even qualitative reproduction of the experimental trend requires scaling down the ion charges according to the Leontyev-Stuchebrukhov correction. On the other hand, the GROMOS force field fails in reproducing the experimentally confirmed capillary activity of TMAI. Molecular dynamics simulation results show that, among the two ions, iodide has a clearly larger surface affinity than tetramethylammonium (TMA+). Further, the adsorption of the I- anions is strictly limited to the first molecular layer beneath the liquid-vapor interface, which is followed by several layers of their depletion. On the other hand, the net negative charge of the surface layer, caused by the excess amount of I- with respect to TMA+, is compensated by a diffuse layer of adsorbed TMA+ cations, extending to or beyond the fourth molecular layer beneath the liquid surface.
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Affiliation(s)
- Louisa McFegan
- Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | | | - Péter Márton
- Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
| | - Zoltán Hórvölgyi
- Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
| | | | - György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 6, H-3300 Eger, Hungary
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5
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Hantal G, Kolafa J, Sega M, Jedlovszky P. Single-Particle Dynamics at the Intrinsic Surface of Aqueous Alkali Halide Solutions. J Phys Chem B 2021; 125:665-679. [PMID: 33423500 DOI: 10.1021/acs.jpcb.0c09989] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The distribution of ions in the proximity of the liquid-vapor interface of their aqueous solution has been the subject of an intense debate during the last decade. The effects of ionic polarizability have been one of its salient aspects. Much less has been said about the corresponding dynamical properties, which are substantially unexplored. Here, we investigate the single-particle dynamics at the liquid-vapor interface of several alkali halide solutions, using molecular dynamics simulations with polarizable and nonpolarizable force fields and intrinsic surface analysis. We analyze the diffusion coefficient, residence time, and velocity autocorrelation function of water and ions and investigate how these properties depend on the molecular layer where they reside. While anions are found in the first molecular layer for relatively long times, cations are only making quick excursions into it, thanks to thermal fluctuations. The in-layer residence time of ions and their molar fraction in the layer turned out to be linearly dependent on each other. We interpret this unexpected result using a simple two-state model. In addition, we found that, unlike water and other neat molecular liquids that show a different diffusion mechanism at the surface than in the bulk of their liquid phase, ions do not enjoy enhanced mobility in the surface layer of their aqueous solution. This result indicates that ions in the surface layer are shielded by their nearest water neighbors from being exposed to the vapor phase as much as possible. Such positions are available for the ions at the negatively curved troughs of the molecularly rugged liquid surface.
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Affiliation(s)
- György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, Vienna A-1190, Austria
| | - Jiří Kolafa
- Department of Physical Chemistry, University of Chemistry and Technology, Prague CZ-166 28 Prague 6, Czech Republic
| | - Marcello Sega
- Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Fürther Straße 248, Nürnberg D-90429, Germany
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka utca 6, Eger H-3300, Hungary
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6
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Hantal G, Horváth RA, Kolafa J, Sega M, Jedlovszky P. Surface Affinity of Alkali and Halide Ions in Their Aqueous Solution: Insight from Intrinsic Density Analysis. J Phys Chem B 2020; 124:9884-9897. [PMID: 33084342 DOI: 10.1021/acs.jpcb.0c05547] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The surface tension of all aqueous alkali halide solutions is higher than that of pure water. According to the Gibbs adsorption equation, this indicates a net depletion of these ions in the interfacial region. However, simulations and experiments show that large, soft ions, such as I-, can accumulate at the liquid/vapor interface. The presence of a loose hydration shell is usually considered to be the reason for this behavior. In this work, we perform computer simulations to characterize the liquid-vapor interface of aqueous alkali chloride and sodium halide solutions systematically, considering all ions from Li+ to Cs+ and from F- to I-. Using computational methods for the removal of surface fluctuations, we analyze the structure of the interface at a dramatically enhanced resolution, showing that the positive excess originates in the very first molecular layer and that the next 3-4 layers account for the net negative excess. With the help of a fictitious system with charge-inverted ion pairs, we also show that it is not possible to rationalize the surface affinity of ions in solutions in terms of the properties of anions and cations separately. Moreover, the surface excess is generally dominated by the smaller of the two ions.
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Affiliation(s)
- György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria
| | - Réka A Horváth
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | - Jiří Kolafa
- Department of Physical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic
| | - Marcello Sega
- Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Fürther Straße 248, D-90429 Nürnberg, Germany
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka utca 6, H-3300 Eger, Hungary
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7
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Zhao X, Nathanson GM, Andersson GG. Experimental Depth Profiles of Surfactants, Ions, and Solvent at the Angstrom Scale: Studies of Cationic and Anionic Surfactants and Their Salting Out. J Phys Chem B 2020; 124:2218-2229. [PMID: 32075369 DOI: 10.1021/acs.jpcb.9b11686] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neutral impact ion scattering spectroscopy (NICISS) is used to measure the depth profiles of ionic surfactants, counterions, and solvent molecules on the angstrom scale. The chosen surfactants are 0.010 m tetrahexylammonium bromide (THA+/Br-) and 0.0050 m sodium dodecyl sulfate (Na+/DS-) in the absence and presence of 0.30 m NaBr in liquid glycerol. NICISS determines the depth profiles of the elements C, O, Na, S, and Br through the loss in energy of 5 keV He atoms that travel into and out of the liquid, which is then converted into depth. In the absence of NaBr, we find that THA+ and its Br- counterion segregate together because of charge attraction, forming a narrow double layer that is 10 Å wide and 150 times more concentrated than in the bulk. With the addition of NaBr, THA+ is "salted out" to the surface, increasing the interfacial Br- concentration by 3-fold and spreading the anions over a ∼30 Å depth. Added NaBr similarly increases the interfacial concentration of DS- ions and broadens their positions. Conversely, the dissolved Br- ions are significantly depleted over a depth of 0-40 Å from the surface because of charge repulsion from DS- ions within the interfacial region. These different interfacial Br- propensities correlate with previously measured gas-liquid reactivities: gaseous Cl2 readily reacts with Br- ions in the presence of THA+ but drops 70-fold in the presence of DS-, demonstrating that surfactant headgroup charge controls the reactivity of Br- through changes in its depth profile.
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Affiliation(s)
- Xianyuan Zhao
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Gilbert M Nathanson
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Gunther G Andersson
- Institute for Nanoscale Science and Technology, Flinders University, Adelaide, SA 5001, Australia
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8
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Horváth RA, Fábián B, Szőri M, Jedlovszky P. Investigation of the liquid-vapour interface of aqueous methylamine solutions by computer simulation methods. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.110978] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Daub CD, Hänninen V, Halonen L. Ab Initio Molecular Dynamics Simulations of the Influence of Lithium Bromide on the Structure of the Aqueous Solution-Air Interface. J Phys Chem B 2019; 123:729-737. [PMID: 30605330 PMCID: PMC6727360 DOI: 10.1021/acs.jpcb.8b10552] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
We
present the results of ab initio molecular dynamics simulations
of the solution–air interface of aqueous lithium bromide (LiBr).
We find that, in agreement with the experimental data and previous
simulation results with empirical polarizable force field models,
Br– anions prefer to accumulate just below the first
molecular water layer near the interface, whereas Li+ cations
remain deeply buried several molecular layers from the interface,
even at very high concentration. The separation of ions has a profound
effect on the average orientation of water molecules in the vicinity
of the interface. We also find that the hydration number of Li+ cations in the center of the slab Nc,Li+–H2O ≈ 4.7 ±
0.3, regardless of the salt concentration. This estimate is consistent
with the recent experimental neutron scattering data, confirming that
results from nonpolarizable empirical models, which consistently predict
tetrahedral coordination of Li+ to four solvent molecules,
are incorrect. Consequently, disruption of the hydrogen bond network
caused by Li+ may be overestimated in nonpolarizable empirical
models. Overall, our results suggest that empirical models, in particular
nonpolarizable models, may not capture all of the properties of the
solution–air interface necessary to fully understand the interfacial
chemistry.
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Affiliation(s)
- Christopher D Daub
- Department of Chemistry , University of Helsinki , P.O. Box 55, Helsinki 00014 , Finland
| | - Vesa Hänninen
- Department of Chemistry , University of Helsinki , P.O. Box 55, Helsinki 00014 , Finland
| | - Lauri Halonen
- Department of Chemistry , University of Helsinki , P.O. Box 55, Helsinki 00014 , Finland
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10
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Bresme F, Robotham O, Chio WIK, Gonzalez MA, Kornyshev A. Debye screening, overscreening and specific adsorption in solutions of organic ions. Phys Chem Chem Phys 2018; 20:27684-27693. [PMID: 30376022 DOI: 10.1039/c8cp04924f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tetrabutylammonium (TBA) and tetraphenylborate (TPB) ions dissolved in dichloroethane (DCE) are widely used in electrochemistry of liquid-liquid interfaces. Unlike alkali halide solutions in water, TBA-TPB-DCE solutions feature large organic ions and a solvent with a dielectric constant almost one order of magnitude lower than that of water. This is expected to dramatically amplify the impact of ionic correlations in the properties of the solution. Here we report atomistic simulations of TBA-TPB-DCE solutions and analyze ion correlations, clustering, and charge screening effects. We target concentrations in the range of 0.01-0.25 molal (m), hence exploring concentration regimes typical for many experimental investigations. We show that the transition from monotonic to oscillatory decay of the charge density, which signals the onset of strong ion correlations, takes place in this concentration interval, leading to overscreening effects. Furthermore, we investigate the distribution and adsorption of ions at the DCE-air interface. Unlike what is observed for small inorganic ions in water at similar concentrations, we find that TPB and TBA ions accumulate near the DCE surface, resulting in significant interfacial clustering and adsorption at concentrations ∼0.25 m. TPB ions adsorb more strongly leading to free energy wells of ∼1-2 kBT. The adsorption modifies significantly the electrostatic potential of the DCE-air interface, which undergoes a shift of 0.2 V in going from pure DCE to TBA-TPB-DCE solutions at 0.25 m.
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Affiliation(s)
- Fernando Bresme
- Department of Chemistry, Imperial College London, White City Campus, 80 Wood Lane, London W12 0BZ, UK.
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11
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Specific cation effects at aqueous solution-vapor interfaces: Surfactant-like behavior of Li + revealed by experiments and simulations. Proc Natl Acad Sci U S A 2017; 114:13363-13368. [PMID: 29078311 DOI: 10.1073/pnas.1707540114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is now well established by numerous experimental and computational studies that the adsorption propensities of inorganic anions conform to the Hofmeister series. The adsorption propensities of inorganic cations, such as the alkali metal cations, have received relatively little attention. Here we use a combination of liquid-jet X-ray photoelectron experiments and molecular dynamics simulations to investigate the behavior of K+ and Li+ ions near the interfaces of their aqueous solutions with halide ions. Both the experiments and the simulations show that Li+ adsorbs to the aqueous solution-vapor interface, while K+ does not. Thus, we provide experimental validation of the "surfactant-like" behavior of Li+ predicted by previous simulation studies. Furthermore, we use our simulations to trace the difference in the adsorption of K+ and Li+ ions to a difference in the resilience of their hydration shells.
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12
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Pohl MN, Richter C, Lugovoy E, Seidel R, Slavíček P, Aziz EF, Abel B, Winter B, Hergenhahn U. Sensitivity of Electron Transfer Mediated Decay to Ion Pairing. J Phys Chem B 2017; 121:7709-7714. [PMID: 28696722 DOI: 10.1021/acs.jpcb.7b06061] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ion pairing in electrolyte solutions remains a topic of discussion despite a long history of research. Very recently, nearest-neighbor mediated electronic de-excitation processes of core hole vacancies (electron transfer mediated decay, ETMD) were proposed to carry a spectral fingerprint of local solvation structure and in particular of contact ion pairs. Here, for the first time, we apply electron-electron coincidence detection to a liquid microjet, and record ETMD spectra of Li 1s vacancies in aqueous solutions of lithium chloride (LiCl) in direct comparison to lithium acetate (LiOAc). A change in the ETMD spectrum dependent on the electrolyte anion identity is observed for 4.5 M salt concentration. We discuss these findings within the framework of the formation and presence of contact ion pairs and the unique sensitivity of ETMD spectroscopy to ion pairing.
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Affiliation(s)
- Marvin N Pohl
- Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development , Albert-Einstein-Str. 15, 12489 Berlin, Germany.,Department of Physics, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
| | - Clemens Richter
- Department of Physics, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany.,Leibniz Institute of Surface Modification (HZB-IOM Joint-Photonic Lab) , Permoserstr. 15, 04318 Leipzig, Germany
| | - Evgeny Lugovoy
- Leibniz Institute of Surface Modification (HZB-IOM Joint-Photonic Lab) , Permoserstr. 15, 04318 Leipzig, Germany
| | - Robert Seidel
- Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development , Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Petr Slavíček
- Department of Physical Chemistry, University of Chemistry and Technology , Technická 5, 16628 Prague, Czech Republic
| | - Emad F Aziz
- Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development , Albert-Einstein-Str. 15, 12489 Berlin, Germany.,Department of Physics, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany.,School of Chemistry, Monash University , 3800 Clayton, Victoria, Australia
| | - Bernd Abel
- Leibniz Institute of Surface Modification (HZB-IOM Joint-Photonic Lab) , Permoserstr. 15, 04318 Leipzig, Germany.,Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, University of Leipzig , Linnéstr. 2, 04103 Leipzig, Germany
| | - Bernd Winter
- Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development , Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Uwe Hergenhahn
- Leibniz Institute of Surface Modification (HZB-IOM Joint-Photonic Lab) , Permoserstr. 15, 04318 Leipzig, Germany.,Max Planck Institute for Plasma Physics , Wendelsteinstr. 1, 17491 Greifswald, Germany
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13
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Cousens NEA, Kucernak ARJ. Reversible ultralow-voltage liquid-liquid electrowetting without a dielectric layer. Faraday Discuss 2017; 199:63-73. [PMID: 28475183 DOI: 10.1039/c7fd00016b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electrowetting-on-dielectric devices typically have operating voltages of 10-20 V. A reduction in the operating voltage could greatly reduce the energy consumption of these devices. Herein, fully reversible one-electrolyte electrowetting of a droplet on a solid metal surface is reported for the first time. A reversible change of 29° for an 800 mV step is achieved. The effects of surface roughness, electrolyte composition, electrolyte concentration and droplet composition are investigated. It was found that there is a dramatic dependence of the reversibility and hysteresis of the system on these parameters, contrary to theoretical predictions. When a 3-chloro-1-propanol droplet is used, a system with no hysteresis and a 40° change in angle are obtained.
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Affiliation(s)
- Nico E A Cousens
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK.
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14
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Fábián B, Sega M, Horvai G, Jedlovszky P. Single Particle Dynamics at the Intrinsic Surface of Various Apolar, Aprotic Dipolar, and Hydrogen Bonding Liquids As Seen from Computer Simulations. J Phys Chem B 2017; 121:5582-5594. [PMID: 28498673 DOI: 10.1021/acs.jpcb.7b02220] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate the single molecule dynamics at the intrinsic liquid/vapor interface of five different molecular liquids (carbon tetrachloride, acetone, acetonitrile, methanol, and water). After assessing that the characteristic residence times in the surface layer are long enough for a meaningful definition of several transport properties within the layer itself, we characterize the dynamics of the individual molecules at the liquid surface by analyzing their normal and lateral mean-square displacements and lateral velocity autocorrelation functions and, in the case of the hydrogen bonding liquids (i.e., water and methanol), also the properties of the hydrogen bonds. Further, dynamical properties as well as the clustering of the molecules residing unusually long in the surface layer are also investigated. The global picture emerging from this analysis is that of a noticeably enhanced dynamics of the molecules at the liquid surface, with diffusion coefficients up to 4 times larger than in the bulk, and the disappearance of the caging effect at the surface of all liquids but water. The dynamics of water is dominated by the strong hydrogen bonding structure also at the liquid surface.
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Affiliation(s)
- Balázs Fábián
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics , Szt. Gellért tér 4, H-1111 Budapest, Hungary.,Institut UTINAM (CNRS UMR 6213), Université Bourgogne Franche-Comté , 16 route de Gray, F-25030 Besançon, France
| | - Marcello Sega
- Faculty of Physics, University of Vienna , Boltzmanngasse 5, A-1090 Vienna, Austria
| | - George Horvai
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics , Szt. Gellért tér 4, H-1111 Budapest, Hungary.,MTA-BME Research Group of Technical Analytical Chemistry, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | - Pál Jedlovszky
- MTA-BME Research Group of Technical Analytical Chemistry, Szt. Gellért tér 4, H-1111 Budapest, Hungary.,Department of Chemistry, Eszterházy Károly University , Leányka u. 6, H-3300 Eger, Hungary
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15
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Faust JA, Sobyra TB, Nathanson GM. Gas-Microjet Reactive Scattering: Collisions of HCl and DCl with Cool Salty Water. J Phys Chem Lett 2016; 7:730-735. [PMID: 26828574 DOI: 10.1021/acs.jpclett.5b02848] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Liquid microjets provide a powerful means to investigate reactions of gases with salty water in vacuum while minimizing gas-vapor collisions. We use this technique to explore the fate of gaseous HCl and DCl molecules impinging on 8 molal LiCl and LiBr solutions at 238 K. The experiments reveal that HCl or DCl evaporate infrequently if they become thermally accommodated at the surface of either solution. In particular, we observe minimal thermal desorption of HCl following HCl collisions and no distinct evidence for rapid, interfacial DCl→HCl exchange following DCl collisions. These results imply that surface thermal motions are not generally strong enough to propel momentarily trapped HCl or DCl back into the gas phase before they ionize and disappear into solution. Instead, only HCl and DCl molecules that scatter directly from the surface escape entry. These recoiling molecules transfer less energy upon collision to LiBr/H2O than to LiCl/H2O, reflecting the heavier mass of Br(-) than of Cl(-) in the interfacial region.
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Affiliation(s)
- Jennifer A Faust
- Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706-1322, United States
| | - Thomas B Sobyra
- Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706-1322, United States
| | - Gilbert M Nathanson
- Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706-1322, United States
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16
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Braga C, Muscatello J, Lau G, Müller EA, Jackson G. Nonequilibrium study of the intrinsic free-energy profile across a liquid-vapour interface. J Chem Phys 2016; 144:044703. [DOI: 10.1063/1.4940137] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- Carlos Braga
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Jordan Muscatello
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Gabriel Lau
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Erich A. Müller
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - George Jackson
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
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Hahn C, Kann ZR, Faust JA, Skinner JL, Nathanson GM. Super-Maxwellian helium evaporation from pure and salty water. J Chem Phys 2016; 144:044707. [PMID: 26827228 DOI: 10.1063/1.4940144] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Helium atoms evaporate from pure water and salty solutions in super-Maxwellian speed distributions, as observed experimentally and modeled theoretically. The experiments are performed by monitoring the velocities of dissolved He atoms that evaporate from microjets of pure water at 252 K and 4-8.5 molal LiCl and LiBr at 232-252 K. The average He atom energies exceed the flux-weighted Maxwell-Boltzmann average of 2RT by 30% for pure water and 70% for 8.5m LiBr. Classical molecular dynamics simulations closely reproduce the observed speed distributions and provide microscopic insight into the forces that eject the He atoms from solution. Comparisons of the density profile and He kinetic energies across the water-vacuum interface indicate that the He atoms are accelerated by He-water collisions within the top 1-2 layers of the liquid. We also find that the average He atom kinetic energy scales with the free energy of solvation of this sparingly soluble gas. This free-energy difference reflects the steeply decreasing potential of mean force on the He atoms in the interfacial region, whose gradient is the repulsive force that tends to expel the atoms. The accompanying sharp decrease in water density suppresses the He-water collisions that would otherwise maintain a Maxwell-Boltzmann distribution, allowing the He atom to escape at high energies. Helium is especially affected by this reduction in collisions because its weak interactions make energy transfer inefficient.
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Affiliation(s)
- Christine Hahn
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | - Zachary R Kann
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | - Jennifer A Faust
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | - J L Skinner
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | - Gilbert M Nathanson
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
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Sega M, Fábián B, Jedlovszky P. Layer-by-layer and intrinsic analysis of molecular and thermodynamic properties across soft interfaces. J Chem Phys 2015; 143:114709. [DOI: 10.1063/1.4931180] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Marcello Sega
- Computational Physics Group, University of Vienna, Sensengasse 8/9, 1090 Vienna, Austria
| | - Balázs Fábián
- Institut UTINAM (CNRS UMR 6213), Université de Franche-Comté, 16 route de Gray, F-25030 Besançon, France
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | - Pál Jedlovszky
- Laboratory of Interfaces and Nanosize Systems, Institute of Chemistry, Eötvös Loránd University, Pázmány P. Stny 1/A, H-1117 Budapest, Hungary
- MTA-BME Research Group of Technical Analytical Chemistry, Szt. Gellért tér 4, H-1111 Budapest, Hungary
- Department of Chemistry, EKF, Leányka u. 6, H-3300 Eger, Hungary
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Ryder OS, Campbell NR, Shaloski M, Al-Mashat H, Nathanson GM, Bertram TH. Role of Organics in Regulating ClNO2 Production at the Air–Sea Interface. J Phys Chem A 2015; 119:8519-26. [DOI: 10.1021/jp5129673] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- O. S. Ryder
- Department
of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
| | - N. R. Campbell
- Department
of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
| | - M. Shaloski
- Department
of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - H. Al-Mashat
- Department
of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
| | - G. M. Nathanson
- Department
of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - T. H. Bertram
- Department
of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
- Department
of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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Daub CD, Åstrand PO, Bresme F. Lithium Ion–Water Clusters in Strong Electric Fields: A Quantum Chemical Study. J Phys Chem A 2015; 119:4983-92. [DOI: 10.1021/acs.jpca.5b01822] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christopher D. Daub
- Department
of Chemistry, Norwegian University of Science and Technology (NTNU) NO-7491, Trondheim, Norway
| | - Per-Olof Åstrand
- Department
of Chemistry, Norwegian University of Science and Technology (NTNU) NO-7491, Trondheim, Norway
| | - Fernando Bresme
- Department
of Chemistry, Norwegian University of Science and Technology (NTNU) NO-7491, Trondheim, Norway
- Department
of Chemistry, Imperial College London SW7 2AZ, London, United Kingdom
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21
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Manna A, Kumar A. Invoking Pairwise Interactions in Water-Promoted Diels-Alder Reactions by using Ionic Liquids as Cosolvents. Chemphyschem 2014; 15:3067-77. [DOI: 10.1002/cphc.201402338] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Indexed: 11/09/2022]
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22
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Soniat M, Rick SW. Charge transfer effects of ions at the liquid water/vapor interface. J Chem Phys 2014; 140:184703. [DOI: 10.1063/1.4874256] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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Yang Y, Laird BB. Thermodynamics and Intrinsic Structure of the Al–Pb Liquid–Liquid Interface: A Molecular Dynamics Simulation Study. J Phys Chem B 2014; 118:8373-80. [DOI: 10.1021/jp5019313] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yang Yang
- Department
of Materials Science and Engineering, University of California, Berkeley, Berkeley, California 94720, United States
| | - Brian B. Laird
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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25
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Neyt JC, Wender A, Lachet V, Szymczyk A, Ghoufi A, Malfreyt P. How does the electronic continuum model perform in the prediction of the surface tension of salt solutions? Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.02.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Stern AC, Baer MD, Mundy CJ, Tobias DJ. Thermodynamics of iodide adsorption at the instantaneous air-water interface. J Chem Phys 2013; 138:114709. [PMID: 23534655 DOI: 10.1063/1.4794688] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We performed molecular dynamics simulations using both polarizable and non-polarizable force fields to study the adsorption of iodide to the air-water interface. A novel aspect of our analysis is that the progress of ion adsorption is measured as the distance from the instantaneous interface, which is defined by a coarse-graining scheme proposed recently by Willard and Chandler ["Instantaneous liquid interfaces," J. Phys. Chem. B 114, 1954-1958 (2010)]. Referring structural and thermodynamic quantities to the instantaneous interface unmasks molecular-scale details that are obscured by thermal fluctuations when the same quantities are referred to an average measure of the position of the interface, such as the Gibbs dividing surface. Our results suggest that an ion adsorbed at the interface resides primarily in the topmost water layer, and the interfacial location of the ion is favored by enthalpy and opposed by entropy.
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Affiliation(s)
- Abraham C Stern
- Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
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Römer F, Wang Z, Wiegand S, Bresme F. Alkali halide solutions under thermal gradients: soret coefficients and heat transfer mechanisms. J Phys Chem B 2013; 117:8209-22. [PMID: 23758489 DOI: 10.1021/jp403862x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report an extensive analysis of the non-equilibrium response of alkali halide aqueous solutions (Na(+)/K(+)-Cl(-)) to thermal gradients using state of the art non-equilibrium molecular dynamics simulations and thermal diffusion forced Rayleigh scattering experiments. The coupling between the thermal gradient and the resulting ionic salt mass flux is quantified through the Soret coefficient. We find the Soret coefficient is of the order of 10(-3) K(-1) for a wide range of concentrations. These relatively simple solutions feature a very rich behavior. The Soret coefficient decreases with concentration at high temperatures (higher than T ∼ 315 K), whereas it increases at lower temperatures. In agreement with previous experiments, we find evidence for sign inversion in the Soret coefficient of NaCl and KCl solutions. We use an atomistic non-equilibrium molecular dynamics approach to compute the Soret coefficients in a wide range of conditions and to attain further microscopic insight on the heat transport mechanism and the behavior of the Soret coefficient in aqueous solutions. The models employed in this work reproduce the magnitude of the Soret coefficient, and the general dependence of this coefficient with temperature and salt concentration. We use the computer simulations as a microscopic approach to establish a correlation between the sign and magnitude of the Soret coefficients and ionic solvation and hydrogen bond structure of the solutions. Finally, we report an analysis of heat transport in ionic solution by quantifying the solution thermal conductivity as a function of concentration. The simulations accurately reproduce the decrease of the thermal conductivity with increasing salt concentration that is observed in experiments. An explanation of this behavior is provided.
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Affiliation(s)
- Frank Römer
- Department of Chemistry, Imperial College London, SW7 2AZ, London, UK
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28
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Enami S, Colussi AJ. Long-range specific ion-ion interactions in hydrogen-bonded liquid films. J Chem Phys 2013; 138:184706. [DOI: 10.1063/1.4803652] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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