1
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Hoek H, Gerber T, Richter C, Dupuy R, Rapf RJ, Oertel H, Buttersack T, Trotochaud L, Karslıoğlu O, Goodacre D, Blum M, Gericke SM, Buechner C, Rude B, Mugele F, Wilson KR, Bluhm H. Compression of a Stearic Acid Surfactant Layer on Water Investigated by Ambient Pressure X-ray Photoelectron Spectroscopy. J Phys Chem B 2024; 128:3755-3763. [PMID: 38578662 PMCID: PMC11033867 DOI: 10.1021/acs.jpcb.4c00451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/14/2024] [Accepted: 03/18/2024] [Indexed: 04/06/2024]
Abstract
We present a combined Langmuir-Pockels trough and ambient pressure X-ray photoelectron spectroscopy (APXPS) study of the compression of stearic acid surfactant layers on neat water. Changes in the packing density of the molecules are directly determined from C 1s and O 1s APXPS data. The experimental data are fit with a 2D model for the stearic acid coverage. Based on the results of these proof-of-principle experiments, we discuss the remaining challenges that need to be overcome for future investigations of the role of surfactants in heterogeneous chemical reactions at liquid-vapor interfaces in combined Langmuir-Pockels trough and APXPS measurements.
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Affiliation(s)
- Harmen Hoek
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Physics
of Complex Fluids − MESA+institute for Nanotechnology, University of Twente,
PO Box 217, 7500 AE Enschede, The Netherlands
| | - Timm Gerber
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Clemens Richter
- Fritz
Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Rémi Dupuy
- Fritz
Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Rebecca J. Rapf
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Holger Oertel
- Fritz
Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Tillmann Buttersack
- Fritz
Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Lena Trotochaud
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Osman Karslıoğlu
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Dana Goodacre
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Department
of Chemical Sciences, The University of
Auckland, Auckland 1142, New Zealand
| | - Monika Blum
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Sabrina M. Gericke
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Christin Buechner
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Bruce Rude
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Frieder Mugele
- Physics
of Complex Fluids − MESA+institute for Nanotechnology, University of Twente,
PO Box 217, 7500 AE Enschede, The Netherlands
| | - Kevin R. Wilson
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Hendrik Bluhm
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Fritz
Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
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2
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Walz MM, Signorelli MRM, Caleman C, Costa LT, Björneholm O. The Surface of Ionic Liquids in Water: From an Ionic Tug of War to a Quasi-Ordered Two-Dimensional Layer. Chemphyschem 2024; 25:e202300551. [PMID: 37991256 DOI: 10.1002/cphc.202300551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/19/2023] [Indexed: 11/23/2023]
Abstract
The sustainable development encompasses the search for new materials for energy storage, gas capture, separation, and solvents in industrial processes that can substitute conventional ones in an efficient and clean manner. Ionic liquids (ILs) emerged and have been advanced as alternative materials for such applications, but an obstacle is their hygroscopicity and the effects on their physical properties in the presence of humidity. Several industrial processes depend on the aqueous interfacial properties, and the main focus of this work is the water/IL interface. The behavior of the aqueous ionic liquids at the water-vacuum interface is representative for their water interfacial properties. Using X-ray photoelectron spectroscopy in combination with molecular dynamics simulations we investigate four aqueous IL systems, and provide molecular level insight on the interfacial behaviour of the ionic liquids, such as ion-pair formation, orientation and surface concentration. We find that ionic liquids containing a chloride anion have a lowered surface enrichment due to the low surface propensity of chloride. In contrast, the ionic liquids containing a bistriflimide anion are extremely surface-enriched due to cooperative surface propensity between the cations and anions, forming a two-dimensional ionic liquid on the water surface at low concentrations.
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Affiliation(s)
- Marie-Madeleine Walz
- Uppsala University, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics, Uppsala, Sweden
- Current address: Novavax AB, Kungsgatan 109, 753 18, Uppsala, Sweden
| | | | - Carl Caleman
- Uppsala University, Department of Physics and Astronomy, X-ray Photon Science, Uppsala, Sweden
- Deutches Elektronen-Synchrotron DESY, Center for Free-electron Laser Science, Hamburg, Germany
| | - Luciano T Costa
- Fluminense Federal University-Outeiro de São João Batista, Institute of Chemistry, MolMod-CS, Niteroi, RJ, Brazil
| | - Olle Björneholm
- Uppsala University, Department of Physics and Astronomy, X-ray Photon Science, Uppsala, Sweden
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3
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Ozon M, Tumashevich K, Lin JJ, Prisle NL. Inversion model for extracting chemically resolved depth profiles across liquid interfaces of various configurations from XPS data: PROPHESY. JOURNAL OF SYNCHROTRON RADIATION 2023; 30:941-961. [PMID: 37610342 PMCID: PMC10481271 DOI: 10.1107/s1600577523006124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 07/12/2023] [Indexed: 08/24/2023]
Abstract
PROPHESY, a technique for the reconstruction of surface-depth profiles from X-ray photoelectron spectroscopy data, is introduced. The inversion methodology is based on a Bayesian framework and primal-dual convex optimization. The acquisition model is developed for several geometries representing different sample types: plane (bulk sample), cylinder (liquid microjet) and sphere (droplet). The methodology is tested and characterized with respect to simulated data as a proof of concept. Possible limitations of the method due to uncertainty in the attenuation length of the photo-emitted electron are illustrated.
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Affiliation(s)
- Matthew Ozon
- Center for Atmospheric Research, University of Oulu, PO Box 4500, Finland
| | | | - Jack J. Lin
- Center for Atmospheric Research, University of Oulu, PO Box 4500, Finland
| | - Nønne L. Prisle
- Center for Atmospheric Research, University of Oulu, PO Box 4500, Finland
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4
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Dupuy R, Filser J, Richter C, Buttersack T, Trinter F, Gholami S, Seidel R, Nicolas C, Bozek J, Egger D, Oberhofer H, Thürmer S, Hergenhahn U, Reuter K, Winter B, Bluhm H. Ångstrom-Depth Resolution with Chemical Specificity at the Liquid-Vapor Interface. PHYSICAL REVIEW LETTERS 2023; 130:156901. [PMID: 37115858 DOI: 10.1103/physrevlett.130.156901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/22/2023] [Indexed: 06/19/2023]
Abstract
The determination of depth profiles across interfaces is of primary importance in many scientific and technological areas. Photoemission spectroscopy is in principle well suited for this purpose, yet a quantitative implementation for investigations of liquid-vapor interfaces is hindered by the lack of understanding of electron-scattering processes in liquids. Previous studies have shown, however, that core-level photoelectron angular distributions (PADs) are altered by depth-dependent elastic electron scattering and can, thus, reveal information on the depth distribution of species across the interface. Here, we explore this concept further and show that the experimental anisotropy parameter characterizing the PAD scales linearly with the average distance of atoms along the surface normal obtained by molecular dynamics simulations. This behavior can be accounted for in the low-collision-number regime. We also show that results for different atomic species can be compared on the same length scale. We demonstrate that atoms separated by about 1 Å along the surface normal can be clearly distinguished with this method, achieving excellent depth resolution.
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Affiliation(s)
- R Dupuy
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, LCPMR, F-75005 Paris Cedex 05, France
| | - J Filser
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - C Richter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - T Buttersack
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - F Trinter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
- Institut für Kernphysik, Goethe-Universität Frankfurt am Main, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - S Gholami
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - R Seidel
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - C Nicolas
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48 91192, Gif-sur-Yvette Cedex, France
| | - J Bozek
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48 91192, Gif-sur-Yvette Cedex, France
| | - D Egger
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - H Oberhofer
- Department of Physics, University of Bayreuth, 95440 Bayreuth, Germany
| | - S Thürmer
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-Ku, Kyoto 606-8502, Japan
| | - U Hergenhahn
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - K Reuter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - B Winter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - H Bluhm
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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5
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Dupuy R, Thürmer S, Richter C, Buttersack T, Trinter F, Winter B, Bluhm H. Core-Level Photoelectron Angular Distributions at the Liquid-Vapor Interface. Acc Chem Res 2023; 56:215-223. [PMID: 36695522 PMCID: PMC9910046 DOI: 10.1021/acs.accounts.2c00678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
ConspectusPhotoelectron spectroscopy (PES) is a powerful tool for the investigation of liquid-vapor interfaces, with applications in many fields from environmental chemistry to fundamental physics. Among the aspects that have been addressed with PES is the question of how molecules and ions arrange and distribute themselves within the interface, that is, the first few nanometers into solution. This information is of crucial importance, for instance, for atmospheric chemistry, to determine which species are exposed in what concentration to the gas-phase environment. Other topics of interest include the surface propensity of surfactants, their tendency for orientation and self-assembly, as well as ion double layers beneath the liquid-vapor interface. The chemical specificity and surface sensitivity of PES make it in principle well suited for this endeavor. Ideally, one would want to access complete atomic-density distributions along the surface normal, which, however, is difficult to achieve experimentally for reasons to be outlined in this Account. A major complication is the lack of accurate information on electron transport and scattering properties, especially in the kinetic-energy regime below 100 eV, a pre-requisite to retrieving the depth information contained in photoelectron signals.In this Account, we discuss the measurement of the photoelectron angular distributions (PADs) as a way to obtain depth information. Photoelectrons scatter with a certain probability when moving through the bulk liquid before being expelled into a vacuum. Elastic scattering changes the electron direction without a change in the electron kinetic energy, in contrast to inelastic scattering. Random elastic-scattering events usually lead to a reduction of the measured anisotropy as compared to the initial, that is, nascent PAD. This effect that would be considered parasitic when attempting to retrieve information on photoionization dynamics from nascent liquid-phase PADs can be turned into a powerful tool to access information on elastic scattering, and hence probing depth, by measuring core-level PADs. Core-level PADs are relatively unaffected by effects other than elastic scattering, such as orbital character changes due to solvation. By comparing a molecule's gas-phase angular anisotropy, assumed to represent the nascent PAD, with its liquid-phase anisotropy, one can estimate the magnitude of elastic versus inelastic scattering experienced by photoelectrons on their way to the surface from the site at which they were generated. Scattering events increase with increasing depth into solution, and thus it is possible to correlate the observed reduction in angular anisotropy with the depth below the surface along the surface normal.We will showcase this approach for a few examples. In particular, our recent works on surfactant molecules demonstrated that one can indeed probe atomic distances within these molecules with a high sensitivity of ∼1 Å resolution along the surface normal. We were also able to show that the anisotropy reduction scales linearly with the distance along the surface normal within certain limits. The limits and prospects of this technique are discussed at the end, with a focus on possible future applications, including depth profiling at solid-vapor interfaces.
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Affiliation(s)
- Rémi Dupuy
- Fritz-Haber-Institut
der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195Berlin, Germany,
| | - Stephan Thürmer
- Department
of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho,
Sakyo-Ku, Kyoto606-8502, Japan
| | - Clemens Richter
- Fritz-Haber-Institut
der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195Berlin, Germany
| | - Tillmann Buttersack
- Fritz-Haber-Institut
der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195Berlin, Germany
| | - Florian Trinter
- Fritz-Haber-Institut
der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195Berlin, Germany,Institut
für Kernphysik, Goethe-Universität
Frankfurt am Main, Max-von-Laue-Strasse
1, Frankfurt am Main60438, Germany
| | - Bernd Winter
- Fritz-Haber-Institut
der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195Berlin, Germany
| | - Hendrik Bluhm
- Fritz-Haber-Institut
der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195Berlin, Germany,
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6
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Ammann M, Artiglia L. Solvation, Surface Propensity, and Chemical Reactions of Solutes at Atmospheric Liquid-Vapor Interfaces. Acc Chem Res 2022; 55:3641-3651. [PMID: 36472357 PMCID: PMC9774673 DOI: 10.1021/acs.accounts.2c00604] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
surface is covered by oceans, a large number of liquid aerosol particles fill the air, and clouds hold a tiny but critical fraction of Earth's water in the air to influence our climate and hydrology, enabling the lives of humans and ecosystems. The surfaces of these liquids provide the interface for the transfer of gases, for nucleation processes, and for catalyzing important chemical reactions. Coupling a range of spectroscopic tools to liquid microjets has become an important approach to better understanding dynamics, structure, and chemistry at liquid interfaces. Liquid microjets offer stability in vacuum and ambient pressure environments, thus also allowing X-ray photoelectron spectroscopy (XPS) with manageable efforts in terms of differential pumping. Liquid microjets are operated at speeds sufficient to allow for a locally equilibrated surface in terms of water dynamics and solute surface partitioning. XPS is based on the emission of core-level electrons, the binding energy of which is selective for the element and its chemical environment. Inelastic scattering of electrons establishes the probing depth of XPS in the nanometer range and thus its surface sensitivity.In this Account, we focus on aqueous solutions relevant to the surface of oceans, aqueous aerosols, or cloudwater. We are interested in understanding solvation and acid dissociation at the interface, interfacial aspects of reactions with gas-phase reactants, and the interplay of ions with organic molecules at the interface. The strategy is to obtain a link between the molecular-level picture and macroscopic properties and reactivity in the atmospheric context.We show consistency between surface tension and XPS for a range of surface-active organic species as an important proof for interrogating an equilibrated liquid surface. Measurements with organic acids and amines offer important insight into the question of apparent acidity or basicity at the interface. Liquid microjet XPS has settled the debate of the surface enhancement of halide ions, shown using the example of bromide and its oxidation products. Despite the absence of a strong enhancement for the bromide ion, its rate of oxidation by ozone is surface catalyzed through the stabilization of the bromide ozonide intermediate at the interface. In another reaction system, the one between Fe2+ and H2O2, a similar intermediate in the form of highly valent iron species could not be detected by XPS under the experimental conditions employed, shedding light on the abundance of this intermediate in the environment but also on the constraints within which surface species can be detected. Emphasizing the importance of electrostatic effects, we show how a cationic surfactant attracts charged bromide anions to the interface, accompanied by enhanced oxidation rates by ozone, overriding the role of surfactants as a barrier for the access of gas-phase reactants. The reactivity and structure at interfaces thus result from a subtle balance between hygroscopic and hydrophobic interactions, electrostatic effects, and the structural properties of both liquids and solutes.
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7
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Björneholm O, Öhrwall G, de Brito AN, Ågren H, Carravetta V. Superficial Tale of Two Functional Groups: On the Surface Propensity of Aqueous Carboxylic Acids, Alkyl Amines, and Amino Acids. Acc Chem Res 2022; 55:3285-3293. [PMID: 36472092 PMCID: PMC9730837 DOI: 10.1021/acs.accounts.2c00494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The gas-liquid interface of water is environmentally relevant due to the abundance of aqueous aerosol particles in the atmosphere. Aqueous aerosols often contain a significant fraction of organics. As aerosol particles are small, surface effects are substantial but not yet well understood. One starting point for studying the surface of aerosols is to investigate the surface of aqueous solutions. We review here studies of the surface composition of aqueous solutions using liquid-jet photoelectron spectroscopy in combination with theoretical simulations. Our focus is on model systems containing two functional groups, the carboxylic group and the amine group, which are both common in atmospheric organics. For alkanoic carboxylic acids and alkyl amines, we find that the surface propensity of such amphiphiles can be considered to be a balance between the hydrophilic interactions of the functional group and the hydrophobic interactions of the alkyl chain. For the same chain length, the neutral alkyl amine has a lower surface propensity than the neutral alkanoic carboxylic acid, whereas the surface propensity of the corresponding alkyl ammonium ion is higher than that of the alkanoic carboxylate ion. This different propensity leads to a pH-dependent surface composition which differs from the bulk, with the neutral forms having a much higher surface propensity than the charged ones. In aerosols, alkanoic carboxylic acids and alkyl amines are often found together. For such mixed systems, we find that the oppositely charged molecular ions form ion pairs at the surface. This cooperative behavior leads to a more organic-rich and hydrophobic surface than would be expected in a wide, environmentally relevant pH range. Amino acids contain a carboxylic and an amine group, and amino acids of biological origin are found in aerosols. Depending on the side group, we observe surface propensity ranging from surface-depleted to enriched by a factor of 10. Cysteine contains one more titratable group, which makes it exhibit more complex behavior, with some protonation states found only at the surface and not in the bulk. Moreover, the presence of molecular ions at the surface is seen to affect the distribution of inorganic ions. As the charge of the molecular ions changes with protonation, the effects on the inorganic ions also exhibit a pH dependence. Our results show that for these systems the surface composition differs from the bulk and changes with pH and that the results obtained for single-component solutions may be modified by ion-ion interactions in the case of mixed solutions.
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Affiliation(s)
- Olle Björneholm
- Division
of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden,
| | - Gunnar Öhrwall
- MAX
IV Laboratory, Lund University, Box 118, SE-22100 Lund, Sweden
| | - Arnaldo Naves de Brito
- Department
of Applied Physics, Institute of Physics
“Gleb Wataghin”, Campinas University, CEP, 13083859 Campinas
SP, Brazil
| | - Hans Ågren
- Division
of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Vincenzo Carravetta
- CNR-IPCF, Institute
of Chemical Physical Processes, via G. Moruzzi 1, I-56124 Pisa, Italy
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8
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Chen Z, Li Z, Hu J, Tian SX. Electron Impact with the Liquid-Vapor Interface. Acc Chem Res 2022; 55:3071-3079. [PMID: 36251270 DOI: 10.1021/acs.accounts.2c00428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Reaction dynamics in the liquid-vapor interface is one of the crucial physical sciences but is still starving for in-depth exploration. It is challenging to selectively detect the interfacial species or the yields of chemical reaction therein, meanwhile shielding or reducing the interference from the vapor and liquid bulk. Mass spectrometry is a straightforward method but is also frustrated in such a selective detection. Using a liquid microjet in combination with a pulsed electron beam, a linear time-of-flight mass spectrometer, and a quadrupole mass filter, we recently innovated time-delayed mass spectrometry for investigations of the liquid-vapor interface. In this Account, we illustrate how this unique method succeeds in disentangling different sources, i.e., the vapor and liquid-vapor interface, of the ionic yields of the electron impacts with a liquid beam of alcohol in vacuum. These achievements are basically attributed to the application of an onion-peeling strategy in the ion detection. Concretely, the microsecond time scale of molecular volatilization can be resolved well by tuning the delay time between the nanosecond pulses of incident electron bunch and ion attractor. First, the specific orientation of the interfacial molecule, i.e., a well-known fact about the hydrophobic hydrocarbon groups pointing outside the liquid surface of alcohol, is validated again. More importantly, the dynamic features of time-delayed mass spectra, in particular, for the ionic yields from the liquid-vapor interface, are rationalized explicitly. Moreover, we demonstrate evidence of in situ molecular dimers in the liquid-vapor interface of 1-propanol. As the first example of electron-induced reaction in the liquid-vapor interface, dimethyl ether can be synthesized in the liquid methanol interface due to local interfacial acidification by high-energy electron impacts. On the contrary, the low energy electron can lead to local basicity through dissociative electron attachment (DEA). Besides the primary low-energy electrons, the low-energy secondary and inelastically scattered electrons in the higher-energy impacts of the primary electrons can also participate in the DEA process. In contrast to the gas- or solid-phase DEAs, that in the liquid-vapor interface shows distinct differences in both the types and efficiencies of anionic products. With these and efforts in the future, we develop a molecular-level understanding of how the chemical reactions happen in the liquid-vapor interface.
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Affiliation(s)
| | | | | | - Shan Xi Tian
- Hefei National Laboratory, University of Science and Technology of China, Wangjiang West Road, Hefei230088, China
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9
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Dowek D, Decleva P. Trends in angle-resolved molecular photoelectron spectroscopy. Phys Chem Chem Phys 2022; 24:24614-24654. [DOI: 10.1039/d2cp02725a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this perspective article, main trends of angle-resolved molecular photoelectron spectroscopy in the laboratory up to the molecular frame, in different regimes of light-matter interactions, are highlighted with emphasis on foundations and most recent applications.
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Affiliation(s)
- Danielle Dowek
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay, 91405 Orsay, France
| | - Piero Decleva
- CNR IOM and Dipartimento DSCF, Università di Trieste, Trieste, Italy
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10
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Flavell W. Spiers Memorial Lecture: Prospects for photoelectron spectroscopy. Faraday Discuss 2022; 236:9-57. [DOI: 10.1039/d2fd00071g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An overview is presented of recent advances in photoelectron spectroscopy, focussing on advances in in situ and time-resolved measurements, and in extending the sampling depth of the technique. The future...
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