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Abstract
The state of oxygen in aqueous supersaturated solutions prepared by different methods was studied using high-resolution ultrasonic spectroscopy in combination with other techniques. This allowed for nondestructive evaluation of the properties of oxygen solute particles, composed of oxygen molecules and surrounding (coordinating) molecules of water, at equilibrium, supersaturated conditions, and different temperatures and concentrations of O2. The results were compared with the behaviors of other types of solutes in water, including H2O2, which has similar molecular size and mass to O2 but is characterized by a significantly different type of interaction with water molecules. Additionally, theoretical modeling was performed to assess the ultrasonic characteristics of dispersions of oxygen nanobubbles stabilized by a surface electrical charge. The obtained data indicate a clathrate-like organization of water in the coordination shells of single molecules of O2. We did not find any signs of formation of clusters of oxygen molecules in supersaturated solutions. No quantifiable presence of oxygen nanobubbles in the solutions was detected. The state of O2 molecules was not affected by supersaturation within the analyzed concentration range of oxygen. The results also demonstrated the potential of the ultrasonic technique in precision real-time nondestructive monitoring of oxygen solubilization and outgassing processes.
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Affiliation(s)
- Yuelong Li
- School of Chemistry, College of Life Science , University College Dublin , Belfield Campus , Dublin 4 , Ireland
| | - Vitaly Buckin
- School of Chemistry, College of Life Science , University College Dublin , Belfield Campus , Dublin 4 , Ireland
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2
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Jeyachandran YL, Meyer F, Benkert A, Bär M, Blum M, Yang W, Reinert F, Heske C, Weinhardt L, Zharnikov M. Investigation of the Ionic Hydration in Aqueous Salt Solutions by Soft X-ray Emission Spectroscopy. J Phys Chem B 2016; 120:7687-95. [PMID: 27442708 DOI: 10.1021/acs.jpcb.6b03952] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Understanding the molecular structure of the hydration shells and their impact on the hydrogen bond (HB) network of water in aqueous salt solutions is a fundamentally important and technically relevant question. In the present work, such hydration effects were studied for a series of representative salt solutions (NaCl, KCl, CaCl2, MgCl2, and KBr) by soft X-ray emission spectroscopy (XES) and resonant inelastic soft X-ray scattering (RIXS). The oxygen K-edge XES spectra could be described with three components, attributed to initial state HB configurations in pure water, water molecules that have undergone an ultrafast dissociation initiated by the X-ray excitation, and water molecules in contact with salt ions. The behavior of the individual components, as well as the spectral shape of the latter component, has been analyzed in detail. In view of the role of ions in such effects as protein denaturation (i.e., the Hofmeister series), we discuss the ion-specific nature of the hydration shells and find that the results point to a predominant role of anions as compared to cations. Furthermore, we observe a concentration-dependent suppression of ultrafast dissociation in all salt solutions, associated with a significant distortion of intact HB configurations of water molecules facilitating such a dissociation.
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Affiliation(s)
- Y L Jeyachandran
- Angewandte Physikalische Chemie, Universität Heidelberg , Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - F Meyer
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - A Benkert
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.,Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT) , Hermann-v.-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - M Bär
- Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Hahn-Meitner-Platz 1, 14109 Berlin, Germany.,Institute für Physik und Chemie, Brandenburgische Technische Universität Cottbus-Senftenberg , Platz der Deutschen Einheit 1, 03046 Cottbus, Germany.,Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , 4505 Maryland Parkway, Las Vegas, Nevada 89154-4003, United States
| | - M Blum
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , 4505 Maryland Parkway, Las Vegas, Nevada 89154-4003, United States
| | - W Yang
- Advanced Light Source (ALS), Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, California 94720, United States
| | - F Reinert
- Experimentelle Physik VII, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - C Heske
- Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT) , Hermann-v.-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.,Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , 4505 Maryland Parkway, Las Vegas, Nevada 89154-4003, United States.,Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT) , Engesserstrasse 18/20, 76028 Karlsruhe, Germany
| | - L Weinhardt
- Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT) , Hermann-v.-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.,Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , 4505 Maryland Parkway, Las Vegas, Nevada 89154-4003, United States.,Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT) , Engesserstrasse 18/20, 76028 Karlsruhe, Germany
| | - M Zharnikov
- Angewandte Physikalische Chemie, Universität Heidelberg , Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
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Lee CW, Lee PR, Kim YK, Kang H. Mechanistic study of proton transfer and H∕D exchange in ice films at low temperatures (100–140K). J Chem Phys 2007; 127:084701. [PMID: 17764278 DOI: 10.1063/1.2759917] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have examined the elementary molecular processes responsible for proton transfer and HD exchange in thin ice films for the temperature range of 100-140 K. The ice films are made to have a structure of a bottom D(2)O layer and an upper H(2)O layer, with excess protons generated from HCl ionization trapped at the D(2)OH(2)O interface. The transport behavior of excess protons from the interfacial layer to the ice film surface and the progress of the HD exchange reaction in water molecules are examined with the techniques of low energy sputtering and Cs(+) reactive ion scattering. Three major processes are identified: the proton hopping relay, the hop-and-turn process, and molecular diffusion. The proton hopping relay can occur even at low temperatures (<120 K), and it transports a specific portion of embedded protons to the surface. The hop-and-turn mechanism, which involves the coupling of proton hopping and molecule reorientation, increases the proton transfer rate and causes the HD exchange of water molecules. The hop-and-turn mechanism is activated at temperatures above 125 K in the surface region. Diffusional mixing of H(2)O and D(2)O molecules additionally contributes to the HD exchange reaction at temperatures above 130 K. The hop-and-turn and molecular diffusion processes are activated at higher temperatures in the deeper region of ice films. The relative speeds of these processes are in the following order: hopping relay>hop and turn>molecule diffusion.
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Affiliation(s)
- Chang-Woo Lee
- Department of Chemistry, Seoul National University, Gwanak-gu, Seoul 151-747, Republic of Korea
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Höfft O, Bahr S, Himmerlich M, Krischok S, Schaefer JA, Kempter V. Electronic structure of the surface of the ionic liquid [EMIM][Tf(2)N] studied by metastable impact electron spectroscopy (MIES), UPS, and XPS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:7120-3. [PMID: 16893200 DOI: 10.1021/la060943v] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The near-surface electronic structure of the room-temperature ionic liquid (RT-IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][Tf(2)N]) has been investigated with the combination of the electron spectroscopies metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS (HeI and HeII)), and monochromatized X-ray photoelectron spectroscopy (XPS). We find that the top of the valence band states originates from states of the cation (see also ref 1). The ultimately surface-sensitive technique MIES proves that the surface layer consists of both cations and anions. The temperature dependence of the spectra has been measured between about 160 and 610 K. Information on the glass transition and the possibility for low-temperature distillation of [EMIM][Tf(2)N] at reduced pressures is derived from the present results.
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Affiliation(s)
- O Höfft
- Institut für Physik und Physikalische Technologien, Technische Universität Clausthal, Leibnizstr. 4, D-38678 Clausthal-Zellerfeld, Germany
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Höfft O, Kahnert U, Bahr S, Kempter V. Interaction of NaI with Solid Water and Methanol. J Phys Chem B 2006; 110:17115-20. [PMID: 16928006 DOI: 10.1021/jp0626014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interaction of NaI with amorphous solid water (ASW) and methanol (MeOH) has been investigated with metastable impact electron spectroscopy (MIES), UPS(HeI), and temperature programmed desorption (TPD). We have studied the electron emission from the ionization of the highest-lying states of H(2)O, CH(3)OH, and of 5pI. We have prepared NaI layers on ASW (MeOH) films at about 105 K and annealed them up to about 200 K. Surface segregation of iodide is observed in ASW, as predicted for NaI aqueous solutions. On the other hand, surface segregation is not observed in MeOH, again as predicted for the interaction of NaI with liquid methanol. Electronic properties (ionization potentials, optical band gaps) and water binding energies are reported and are analyzed on the basis of available DFT results for hydrated NaI clusters.
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Affiliation(s)
- O Höfft
- Technische Universität Clausthal, Institut für Physik und Physikalische Technologien, Leibnizstr. 4, D-38678 Clausthal-Zellerfeld, Germany
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Abstract
The interaction of CsF with multilayered water has been investigated with metastable impact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy with HeI (UPS(HeI)). We have studied the emission from the ionization of H2O states 1b1, 3a1, and 1b2; of Cs5p and of F2p. We have prepared CsF-H2O interfaces, namely, CsF layers on thin films of multilayered water and vice versa; they were annealed between 80 and about 280 K. Up to about 100 K, a closed CsF layer can be deposited on H2O and vice versa; no interpenetration of the two components H2O and CsF could be observed. Above 110 K, CsF (H2O) layers deposited on thin H2O (CsF) films (stoichiometry CsF.1.5H2O) gradually transform into a mixed layer containing F, Cs, and H2O species. When annealing, H2O molecules can be detected up to 200 K from the mixed F-Cs-H2O layer (while for pure H2O desorption is essentially complete at 165 K); a water network is not formed under these conditions, and all H2O molecules are involved in bonding with Cs+ and F- ions. When CsF is deposited at 120 K on sufficiently thick water multilayers, full solvation of both F and Cs takes place, even for the species closest to the surface, as long as the stoichiometry remains CsF.(H2O)n with n > 3.
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Affiliation(s)
- A Borodin
- Technische Universität Clausthal, Institut für Physik und Physikalische Technologien, Leibnizstr. 4, D-38678 Clausthal-Zellerfeld, Germany
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Bahr S, Borodin A, Höfft O, Kempter V, Allouche A. Interaction of formic acid with solid water. J Chem Phys 2005; 122:234704. [PMID: 16008470 DOI: 10.1063/1.1929732] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The interaction of formic acid (HCOOH) with solid water, deposited on tungsten at 80 K, was investigated. We have prepared and annealed formic acid (FA)/water interfaces (FA layers on thin films of solid water and H(2)O adlayers on thin FA films). Metastable impact electron spectroscopy and ultraviolet photoemission spectroscopy (He I and II) were utilized to study the electron emission from the 10a' to 6a' molecular orbitals (MOs) of FA, and the 1b(1), 3a(1), and 1b(2) MOs of H(2)O. These spectra were compared with results of density-functional theory calculations on FA-H(2)O complexes reported in Ref. 14 [A. Allouche, J. Chem. Phys. 122, 234703(2005), (preceding paper)]. Temperature programmed desorption was applied for information on the desorption kinetics. Initially, FA is adsorbed on top of the water film. The FA spectra are distorted with respect to those from FA monomers; it is concluded that a strong interaction exists between the adsorbates. Even though partial solvation of FA species takes place during annealing, FA remains in the top layer up to the desorption of the water film. When H(2)O molecules are offered to FA films at 80 K, no water network is formed during the initial stage of water exposure; H(2)O molecules interact individually via H bonds with the formic acid network. Experiment and theory agree that no water-induced deprotonation of the formic acid molecules takes place.
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Affiliation(s)
- S Bahr
- Institut für Physik und Physikalische Technologien, Technische Universität Clausthal, D-38678 Clausthal-Zellerfeld, Germany
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