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Recent Publications


Do water's electrons care about electrolytes?. Chem. Sci. (2018). doi:10.1039/C8SC03381A

Marvin N. Pohl, Eva Muchová, Robert Seidel, Hebatallah Ali, Štěpán Sršeň, Iain Wilkinson, Bernd Winter and Petr Slavíček

Ions have a profound effect on the geometrical structure of liquid water and an aqueous environment is known to change the electronic structure of ions. Here we combine photoelectron spectroscopy measurements from liquid microjets with molecular dynamical and quantum chemical calculations to address the reverse question, to what extent do ions affect the electronic structure of liquid water? We study aqueous solutions of sodium iodide (NaI) over a wide concentration range, from nearly pure water to 8 M solutions, recording spectra in the 5 to 60 eV binding energy range to include all water valence and the solute Na+ 2p, I 4d, and I 5p orbital ionization peaks. We observe that the electron binding energies of the solute ions change only slightly as a function of electrolyte concentration, less than 150 ± 60 meV over an ∼8 M range. Furthermore, the photoelectron spectrum of liquid water is surprisingly mildly affected as we transform the sample from a dilute aqueous salt solution to a viscous, crystalline-like phase. The most noticeable spectral changes are a negative binding energy shift of the water 1b2 ionizing transition (up to −370 ± 60 meV) and a narrowing of the flat-top shape water 3a1 ionization feature (up to 450 ± 90 meV). A novel computationally efficient technique is introduced to calculate liquid-state photoemission spectra using small clusters from molecular dynamics (MD) simulations embedded in dielectric continuum. This theoretical treatment captured the characteristic positions and structures of the aqueous photoemission peaks, reproducing the experimentally observed narrowing of the water 3a1 feature and weak sensitivity of the water binding energies to electrolyte concentration. The calculations allowed us to attribute the small binding energy shifts to ion-induced disruptions of intermolecular electronic interactions. Furthermore, they demonstrate the importance of considering concentration-dependent screening lengths for a correct description of the electronic structure of solvated systems. Accounting for electronic screening, the calculations highlight the minimal effect of electrolyte concentration on the 1b1 binding energy reference, in accord with the experiments. This leads us to a key finding that the isolated, lowest-binding-energy, 1b1, photoemission feature of liquid water is a robust energetic reference for aqueous liquid microjet photoemission studies.

Molecular species forming at the α-Fe2O3 nanoparticle–aqueous solution interface. Chem. Sci. (2018). doi:10.1039/C7SC05156E

Hebatallah Ali, Robert Seidel, Marvin N. Pohl, and Bernd Winter

We report on electronic structure measurements of the interface between hematite nanoparticles (6 nm diameter) and aqueous solutions. Using soft X-ray photoelectron spectroscopy from a liquid microjet we detect valence and core-level photoelectrons as well as Auger electrons from liquid water, from the nanoparticle–water interface, and from the interior of the aqueous-phase nanoparticles. Most noteworthy, the method is shown to be sufficiently sensitive for the detection of adsorbed hydroxyl species, resulting from H2O dissociation at the nanoparticle surface in aqueous solution. We obtain signal from surface OH from resonant, non-resonant, and from so-called partial-electron-yield X-ray absorption (PEY-XA) spectra. In addition, we report resonant photoelectron measurements at the iron 2p excitation. The respective Fe iron 2p3/2 edge (L3-edge) PEY-XA spectra exhibit two main absorption peaks with their energies being sensitive to the chemical environment of the Fe3+ ions at the nanoparticle–solution interface. This manifests in the 10Dq value which is a measure of the ligand-field strength. Furthermore, an observed intensity variation of the pre-peak, when comparing the PEY-XA spectra for different iron Auger-decay channels, can be assigned to different extents of electron delocalization. From the experimental fraction of local versus non-local autoionization signals we then find a very fast, approximately 1 fs, charge transfer time from interfacial Fe3+ into the environment. The present study, which is complementary to ambient-pressure photoemission studies on solid-electrolyte systems, also highlights the multiple aspects of photoemission that need to be explored for a full characterization of the transition-metal-oxide nanoparticle surface in aqueous phase.


Bulk-Sensitive Detection of the Total Ion Yield for X-ray Absorption Spectroscopy in Liquid Cells. J. Phys. Chem. Lett. (2017). doi:10.1021/acs.jpclett.7b02381

Daniela Schön, Ronny Golnak, Marc F. Tesch, Bernd Winter, Juan-Jesus Velasco-Velez, Emad F. Aziz, and Jie Xiao

Detection of ionic current with two electrodes installed in a liquid cell has been established previously as an effective method, termed as total ion yield (TIY), to acquire X-ray absorption (XA) spectra of liquid solutions behind a membrane. In this study, the exact locations where TIY signals are generated are further investigated and unequivocally identified. The detected ionic current stems dominantly from the bulk solution species while only marginally from the species located at the membrane–solution interface. Such a two-electrode TIY detection in a liquid cell combines the advantages of bulk sensitivity of fluorescence yield and high signal strength (for light elements) of electron yield, exhibiting its novel and promising role in the XA spectroscopy measurements of liquid cells.

Detection of the electronic structure of iron-(III)-oxo oligomers forming in aqueous solutions. Phys. Chem. Chem. Phys. (2017). doi:10.1039/C7CP06945F

Robert Seidel, Katrin Kraffert, Anke Kabelitz, Marvin N. Pohl, Ralph Kraehnert, Franziska Emmerling, and Bernd Winter

The nature of the small iron-oxo oligomers in iron-(III) aqueous solutions has a determining effect on the chemical processes that govern the formation of nanoparticles in aqueous phase. Here we report on a liquid-jet photoelectron-spectroscopy experiment for the investigation of the electronic structure of the occurring iron-oxo oligomers in FeCl3 aqueous solutions. The only iron species in the as-prepared 0.75 M solution are Fe3+ monomers. Addition of NaOH initiates Fe3+ hydrolysis which is followed by the formation of iron-oxo oligomers. At small enough NaOH concentrations, corresponding to approximately [OH]/[Fe] = 0.2–0.25 ratio, the iron oligomers can be stabilized for several hours without engaging in further aggregation. Here, we apply a combination of non-resonant as well as iron 2p and oxygen 1s resonant photoelectron spectroscopy from a liquid microjet to detect the electronic structure of the occurring species. Specifically, the oxygen 1s partial electron yield X-ray absorption (PEY-XA) spectra are found to exhibit a peak well below the onset of liquid water and OH (aq) absorption. The iron 2p absorption gives rise to signal centered between the main absorption bands typical for aqueous Fe3+. Absorption bands in both PEY-XA spectra are found to correlate with an enhanced photoelectron peak near 20 eV binding energy, which demonstrates the sensitivity of resonant photoelectron (RPE) spectroscopy to mixing between iron and ligand orbitals. These various signals from the iron-oxo oligomers exhibit maximum intensity at [OH]/[Fe] = 0.25 ratio. For the same ratio, we observe changes in the pH as well as in complementary Raman spectra, which can be assigned to the transition from monomeric to oligomeric species. At approximately [OH]/[Fe] = 0.3 we begin to observe particles larger than 1 nm in radius, detected by small-angle X-ray scattering.

Specific Cation Effects at Aqueous Solution−Vapor Interfaces: Surfactant-Like Behavior of Li+ Revealed by Experiments and Simulations. Proc. Natl. Acad. Sci. (2017). doi:10.1073/pnas.1707540114

Kathryn A. Perrine, Krista M. Parry, Abraham C. Stern, Marijke H. C. Van Spyk, Michael J. Makowski, J. Alfredo Freites, Bernd Winter, Douglas J. Tobias, and John C. Hemminger

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.

Advances in Liquid Phase Soft-X-ray Photoemission Spectroscopy: A New Experimental Setup at BESSY II. Rev. Sci. Instrum. (2017). doi:10.1063/1.4990797

Robert Seidel, Marvin N. Pohl, Hebatallah Ali, Bernd Winter, and Emad F. Aziz

A state-of-the-art experimental setup for soft X-ray photo- and Auger-electron spectroscopy from liquid phase has been built for operation at the synchrotron-light facility BESSY II, Berlin. The experimental station is named SOL3, which is derived from solid, solution, and solar, and refers to the aim of studying solid–liquid interfaces, optionally irradiated by photons in the solar spectrum. SOL3 is equipped with a high-transmission hemispherical electron analyzer for detecting electrons emitted from small molecular aggregates, nanoparticles, or biochemical molecules and their components in (aqueous) solutions, either in vacuum or in an ambient pressure environment. In addition to conventional energy-resolved electron detection, SOL3 enables detection of electron angular distributions by the combination of a ±11° acceptance angle of the electron analyzer and a rotation of the analyzer in the polarization plane of the incoming synchrotron-light beam. The present manuscript describes the technical features of SOL3, and we also report the very first measurements of soft-X-ray photoemission spectra from a liquid microjet of neat liquid water and of TiO2-nanoparticle aqueous solution obtained with this new setup, highlighting the necessity for state-of-the-art electron detection.

Sensitivity of Electron Transfer Mediated Decay to Ion Pairing. J. Phys. Chem. B (2017). doi:10.1021/acs.jpcb.7b06061

Marvin N. Pohl, Clemens Richter, Evgeny Lugovoy, Robert Seidel, Petr Slavíček, Emad F. Aziz, Bernd Abel, Bernd Winter, and Uwe Hergenhahn

Ion pairing in electrolyte solutions remains a topic of discussion despite a long history of research. Very recently, nearest-neighbor mediated electronic deexcitation 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.

Introducing Ionic-Current Detection for X-ray Absorption Spectroscopy in Liquid Cells. J. Phys. Chem. Lett. (2017). doi:10.1021/acs.jpclett.7b00646

Daniela Schön, Jie Xiao, Ronny Golnak, Marc F. Tesch, Bernd Winter, Juan-Jesus Velasco-Velez, and Emad F. Aziz

Photons and electrons are two common relaxation products upon X-ray absorption, enabling fluorescence yield and electron yield detections for X-ray absorption spectroscopy (XAS). The ions that are created during the electron yield process are relaxation products too, which are exploited in this study to produce ion yield for XA detection. The ionic currents measured in a liquid cell filled with water or iron(III) nitrate aqueous solutions exhibit characteristic O K-edge and Fe L-edge absorption profiles as a function of excitation energy. Application of two electrodes installed in the cell is crucial for obtaining the XA spectra of the liquids behind membranes. Using a single electrode can only probe the species adsorbed on the membrane surface. The ionic-current detection, termed as total ion yield (TIY) in this study, also produces an undistorted Fe L-edge XA spectrum, indicating its promising role as a novel detection method for XAS studies in liquid cells.

Aqueous Solution Chemistry of Ammonium Cation in the Auger Time Window. Scientific Reports (2017). doi:10.1038/s41598-017-00756-x

Daniel Hollas, Marvin N. Pohl, Robert Seidel, Emad F. Aziz, Petr Slavíček, and Bernd Winter

We report on chemical reactions triggered by core-level ionization of ammonium (NH4+) cation in aqueous solution. Based on a combination of photoemission experiments from a liquid microjet and high-level ab initio simulations, we identified simultaneous single and double proton transfer occurring on a very short timescale spanned by the Auger-decay lifetime. Molecular dynamics simulations indicate that the proton transfer to a neighboring water molecule leads to essentially complete formation of H3O+ (aq) and core-ionized ammonia (NH3+) (aq) within the ~7 fs lifetime of the nitrogen 1s core hole. A second proton transfer leads to a transient structure with the proton shared between the remaining NH2 moiety and another water molecule in the hydration shell. These ultrafast proton transfers are stimulated by very strong hydrogen bonds between the ammonium cation and water. Experimentally, the proton transfer dynamics is identified from an emerging signal at the high-kinetic energy side of the Auger-electron spectrum in analogy to observations made for other hydrogen-bonded aqueous solutions. The present study represents the most pronounced charge separation observed upon core ionization in liquids so far.

Chemical bonding in aqueous hexacyano cobaltate from photon- and electron-detection perspectives. Scientific Reports (2017). doi:10.1038/srep40811

Sreeju Sreekantan Nair Lalithambika, Kaan Atak, Robert Seidel, Antje Neubauer, Tim Brandenburg, Jie Xiao, Bernd Winter, and Emad F. Aziz

The electronic structure of the [Co(CN)6]3- complex dissolved in water is studied using X-ray spectroscopy techniques. By combining electron and photon detection methods from the solutions ionized or excited by soft X-rays we experimentally identify chemical bonding between the metal center and the CN ligand. Non-resonant photoelectron spectroscopy provides solute electron binding energies, and nitrogen 1 s and cobalt 2p resonant core-level photoelectron spectroscopy identifies overlap between metal and ligand orbitals. By probing resonances we are able to qualitatively determine the ligand versus metal character of the respective occupied and non-occupied orbitals, purely by experiment. For the same excitations we also detect the emitted X-rays, yielding the complementary resonant inelastic X-ray scattering spectra. For a quantitative interpretation of the spectra, we perform theoretical electronic-structure calculations. The latter provide both orbital energies and orbital character which are found to be in good agreement with experimental energies and with experimentally inferred orbital mixing. We also report calculated X-ray absorption spectra, which in conjunction with our orbital-structure analysis, enables us to quantify various bonding interactions with a particular focus on the water-solvent – ligand interaction and the strength of π-backbonding between metal and ligand.

Optical Fluorescence Detected from X-ray Irradiated Liquid Water. J. Phys. Chem. B (2017). doi:10.1021/acs.jpcb.7b00096

Andreas Hans, Christian Ozga, Robert Seidel, Philipp Schmidt, Timo Ueltzhöffer, Xaver Holzapfel, Philip Wenzel, Philipp Reiß, Marvin N. Pohl, Isaak Unger, Emad F. Aziz, Arno Ehresmann, Petr Slavíček , Bernd Winter, and André Knie

Despite its importance, the structure and dynamics of liquid water are still poorly understood in many apsects. Here, we report on the observation of optical fluorescence upon soft X-ray irradiation of liquid water. Detection of spectrally resolved fluorescence was achieved by a combination of the liquid microjet technique and fluorescence spectroscopy. We observe a genuine liquid-phase fluorescence manifested by a broad emission band in the 170–340 nm (4–7 eV) photon wavelength range. In addition, another narrower emission near 300 nm can be assigned to the fluorescence of OH (A state) in the gas phase, the emitting species being formed by Auger electrons escaping from liquid water. We argue that the newly observed broad-band emission of liquid water is relevant in search of extraterrestrial life, and we also envision the observed electron-ejection mechanism to find application for exploring solutes at liquid–vapor interfaces.

Observation of electron-transfer-mediated decay in aqueous solution. Nature Chemistry (2017). doi:10.1038/nchem.2727

Isaak Unger, Robert Seidel, Stephan Thürmer, Marvin N. Pohl, Emad F. Aziz, Lorenz S. Cederbaum, Eva Muchová, Petr Slavíček, Bernd Winter, and Nikolai V. Kryzhevoi

Photoionization is at the heart of X-ray photoelectron spectroscopy (XPS), which gives access to important information on a sample's local chemical environment. Local and non-local electronic decay after photoionization—in which the refilling of core holes results in electron emission from either the initially ionized species or a neighbour, respectively—have been well studied. However, electron-transfer-mediated decay (ETMD), which involves the refilling of a core hole by an electron from a neighbouring species, has not yet been observed in condensed phase. Here we report the experimental observation of ETMD in an aqueous LiCl solution by detecting characteristic secondary low-energy electrons using liquid-microjet soft XPS. Experimental results are interpreted using molecular dynamics and high-level ab initio calculations. We show that both solvent molecules and counterions participate in the ETMD processes, and different ion associations have distinctive spectral fingerprints. Furthermore, ETMD spectra are sensitive to coordination numbers, ion–solvent distances and solvent arrangement.


Erratum: “Multi-reference approach to the calculation of photoelectron spectra including spin-orbit coupling” [J. Chem. Phys. 143, 074104 (2015)]. J. Chem. Phys. (2016). doi:10.1063/1.4961314
G. Grell, S. I. Bokarev, B. Winter, R. Seidel, E. F. Aziz, S. G. Aziz, and O. Kühn

X‐ray and Electron Spectroscopy of Water. Chem. Rev. (2016). doi:10.1021/acs.chemrev.5b00672
T. Fransson, Y. Harada, N. Kosugi, N. A. Besley, B. Winter, J. J. Rehr, L. G. M. Pettersson, and A. Nilsson

Photoelectron spectra of aqueous solutions from first principles. J. Am. Chem. Soc. (2016). doi:10.1021/jacs.6b00225
A. P. Gaiduk, M. Govoni, R. Seidel, J. Skone, B. Winter, and G. Galli

Undistorted X‐ray Absorption Spectroscopy Using s‐Core-Orbital Emissions. J. Phys. Chem. A (2016). doi:10.1021/acs.jpca.6b01699
R. Golnak, J. Xiao, K. Atak, I. Unger, R. Seidel, B. Winter, and E. F. Aziz

Joint Analysis of Radiative and Non- Radiative Electronic Relaxation Upon X-ray Irradiation of Transition Metal Aqueous Solutions. Scientific Reports (2016). doi:10.1038/srep24659
R. Golnak, S. I. Bokarev, R. Seidel, J. Xiao, G. Grell, K. Atak, I. Unger, S. Thürmer, S. G. Aziz, O. Kühn, B. Winter, and E. F. Aziz

Valence Electronic Structure of Aqueous Solutions: Insights from Photoelectron Spectroscopy. Annu. Rev. Phys. Chem. (2016). 10.1146/annurev-physchem-040513-103715
R. Seidel, B. Winter, and S. E. Bradforth

Relaxation Processes in Aqueous Systems upon X‐ray Ionization: Entanglement of Electronic and Nuclear Dynamics. J. Phys. Chem. Lett. (2016). doi:10.1021/acs.jpclett.5b02665
P. Slavícěk, N. V. Kryzhevoi, E. F. Aziz, and B. Winter


Multireference approach to the calculation of photoelectron spectra including spin-orbit coupling. Journal of Chemical Physics (2015). doi:10.1063/1.4928511
G. Grell, S. I. Bokarev, B. Winter, R. Seidel, E. F. Aziz, S. G. Aziz, and O. Kuehn

Ti3+ Aqueous Solution: Hybridization and Electronic Relaxation Probed by State-Dependent Electron Spectroscopy. J. Phys. Chem. B (2015). doi:10.1021/acs.jpcb.5b03337
R. Seidel, K. Atak, S. Thürmer, E. F. Aziz, and B. Winter

Control of X-ray Induced Electron and Nuclear Dynamics in Ammonia and Glycine Aqueous Solution via Hydrogen Bonding. Journal of Physical Chemistry B (2015). doi:10.1021/acs.jpcb.5b07283
I. Unger, D. Hollas, R. Seidel, S. Thuermer, E. F. Aziz, P. Slavicek, and B. Winter

Reply to the 'Comment on "Charge Transfer to Solvent Dynamics in Iodide Aqueous Solution Studied at Ionization Threshold"' by A. Lubcke and H.-H. Ritze. Phys. Chem. Chem. Phys. (2015). doi:10.1039/c5cp01804h
A. Kothe, M. Wilke, A. Moguilevski, N. Engel, B. Winter, I. Y. Kiyan, and E. F. Aziz

Co(III) protoporphyrin IX chloride in solution: spin-state and metal coordination revealed from resonant inelastic X-ray scattering and electronic structure calculations. PCCP (2015). doi:10.1039/C4CP04703F
K. Atak, R. Golnak, J. Xiao, M. Pflüger, T. Brandenburg, B. Winter, and E. F. Aziz

Charge transfer to solvent dynamics in iodide aqueous solution studied at ionization threshold. PCCP (2015). doi:10.1039/C4CP02482F
A. Kothe, M. Wilke, A. Moguilevski, N. Engel, B. Winter, I. Yu. Kiyan, and E. F. Aziz

Exploring the Aqueous Vertical Ionization of Organic Molecules by Molecular Simulation and Liquid Microjet Photoelectron Spectroscopy. J. Phys. Chem. B (2015). doi:10.1021/jp508053m
P. R. Tentscher, R. Seidel, B. Winter, J. J. Guerard, and J. S. Arey

Scientists strike wet gold. Nature Chemistry (2015). doi:10.1038/nchem.2189
B. Winter

Oxidation Half-Reaction of Aqueous Nucleosides and Nucleotides via Photoelectron Spectroscopy Augmented by ab Initio Calculations. JACS (2015). doi:10.1021/ja508149e
Ch. A. Schroeder, E. Pluhařová, R. Seidel, W. P. Schroeder, M. Faubel, P. Slavíček, B. Winter, P. Jungwirth, and S. E. Bradforth


Characterization of the Acetonitrile Aqueous Solution/Vapor Interface by Liquid-Jet X-ray Photoelectron Spectroscopy. J. Phys. Chem. C (2014). doi:10.1021/jp505947h
K. A. Perrine, M. H. C. Van Spyk, A. M. Margarella, B. Winter, M. Faubel, H. Bluhm, and J. C. Hemminger

Comment on "State-Dependent Electron Delocalization Dynamics at the Solute-Solvent Interface: Soft-X-ray Absorption Spectroscopy and Ab Initio Calculations" Reply. Phys. Rev. Lett. (2014). doi:10.1103/PhysRevLett.112.129303
S. I. Bokarev, M. Dantz, E. Suljoti, K. Atak, B. Winter, O. Kuehn, and E. F. Aziz

Proton-Transfer Mediated Enhancement of Nonlocal Electronic Relaxation Processes in X-ray Irradiated Liquid Water. JACS (2014). doi:10.1021/ja5117588
P. Slavíček, B. Winter, L. S. Cederbaum, N. V. Kryzhevoi

DNA Lesion Can Facilitate Base Ionization: Vertical Ionization Energies of Aqueous 8-Oxoguanine and its Nucleoside and Nucleotide. J. Phys. Chem. B (2014). doi:10.1021/jp5111086
V. Palivec, E. Pluhařová, I. Unger, B. Winter, and P. Jungwirth

Deeper Insight into Depth-Profiling of Aqueous Solutions Using Photoelectron Spectroscopy. J. Phys. Chem. C (2014). doi: 10.1021/jp505569c
O. Björneholm, J. Werner, N. Ottosson, G. Öhrwall, V. Ekholm, B. Winter, I. Unger, and J. Söderström

Ultrafast Proton and Electron Dynamics in Core-Ionized Hydrated Hydron Peroxide: Photoemission Measurements with Isotopically Substituted Hydrogen Peroxide. J. Phys. Chem. C (2014). doi:10.1021/jp504707h
I. Unger, S. Thürmer, D. Hollas, E. F. Aziz, B. Winter, and P. Slavíček

The Assistance of the Iron Porphyrin Ligands to the Binding Interaction Between the Fe Center and Small Molecules in Solution. J. Phys. Chem. B (2014). doi:10.1021/jp5023339
J. Xiao, R. Golnak, K. Atak, M. Pflüger, M. N. Pohl, E. Suljoti, B. Winter, and E. F. Aziz

Electronic Structure of Hemin in Solution Studied by Resonant X-ray Emission Spectroscopy and Electronic Structure Calculations. J. Phys. Chem. B (2014). doi:10.1021/jp505129m
K. Atak, R. Golnak, J. Xiao, Jie, E. Suljoti, M. Pflüger, T. Brandenburg, B. Winter, and E. Aziz

Photoemission Spectra and Density Functional Theory Calculations of 3d Transition Metal-Aqua Complexes (Ti-Cu) in Aqueous Solution. J. Phys. Chem. B (2014). doi:10.1021/jp5012389
D. Yepes, R. Seidel, B. Winter, J. Blumberger, and P. Jaque


Unexpectedly Small Effect of the DNA Environment on Vertical Ionization Energies of Aqueous Nucleobases. J. Phys. Chem. Lett. (2013). doi:10.1021/jz402106h
E. Pluhařová, C. Schroeder, R. Seidel, S. E. Bradforth, B. Winter, M. Faubel, P. Slavíček, and P. Jungwirth

Measure of Surface Potential at the Aqueous−Oxide Nanoparticle Interface by XPS from a Liquid Microjet. Nano. Lett. (2013). doi:10.1021/nl402957y
M. A. Brown, A. Beloqui Redondo, M. Sterrer, B. Winter, G. Pacchioni, Z. Abbas, and J. A. van Bokhoven

On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation. Nat. Chem. (2013). doi:10.1038/nchem.1680
S. Thürmer, M. Ončák, N. Ottosson, R. Seidel, U. Hergenhahn, S. E. Bradforth, P. Slavíček, and B Winter

Relaxation of Electronically Excited Hydrogen Peroxide in Liquid Water: Insights from Auger-Electron Emission. J. Phys. Chem. C (2013). doi:10.1021/jp401569w
S. Thürmer , I. Unger , P. Slavíček, and B. Winter

Photoelectron angular distributions from liquid water: Effects of electron scattering. Phys. Rev. Lett. (2013). doi:101103/PhysRevLett.111.173005
S. Thürmer, R. Seidel, M. Faubel, W. Eberhardt, J. C. Hemminger, S. E. Bradforth, and B. Winter

Dissociation of Sulfuric Acid in Aqueous Solution: Determination of the Photoelectron Spectral Fingerprints of H2SO4, HSO4–, and SO42– in Water. J. Phys. Chem. C (2013). doi:10.1021/jp308090k
A. M. Margarella, K. A. Perrine, T. Lewis, M. Faubel, B. Winter, and J. C. Hemminger


Transforming Anion Instability into Stability: Contrasting Photoionization of Three Protonation Forms of the Phosphate Ion upon Moving into Water. J. Phys. Chem. B (2012). doi:10.1021/jp306348b
E. Pluhařová, M. Ončák, R. Seidel, C. Schroeder, W. Schroeder, B. Winter, S. E. Bradforth, P. Jungwirth, and P. Slavíček

Electronic Structures of Formic Acid (HCOOH) and Formate (HCOO-) in Aqueous Solutions. J. Phys. Chem. Lett. (2012). doi:10.1021/jz300510r
M. A. Brown, F. Vila, M. Sterrer, S. Thürmer, B. Winter, M. Ammann, J. J. Rehr, and J. van Bokhoven

First-Principle Protocol for Calculating Ionization Energies and Redox Potentials of Solvated Molecules and Ions: Theory and Application to Aqueous Phenol and Phenolate. J. Phys. Chem. B (2012). doi:10.1021/jp301925k
D. Ghosh, A. Roy, R. Seidel, B. Winter, S.E. Bradforth, and A.I. Krylov

Origin of dark-channel X-ray fluorescence from transition-metal ions in water. J. Am. Chem. Soc. (2102). doi:10.1021/ja207931r
R. Seidel, S. Ghadimi, K. M. Lange, S. Bonhommeau, M. A. Soldatov, R. Golnak, A. Kothe, R. Könnecke, A. Soldatov, S. Thürmer, B. Winter, and E. F. Aziz

Bond-Breaking, Electron-Pushing and Proton-Pulling: Active and Passive Roles in the Interaction between Aqueous Ions and Water as Manifested in the O 1s Auger Decay. J. Phys. Chem. B (2012). doi:10.1021/jp2041247
W. Pokapanich, N. Ottosson, S. Svensson, G. Öhrwall, B. Winter, and O. Björneholm


Does Nitric Acid Dissociate at the Aqueous Solution Surface?. J. Phys. Chem. C (2011). doi:10.1021/jp205842w
T. Lewis, B. Winter, A.C. Stern, M.D. Baer, C.J. Mundy, D. J. Tobias, and J.C. Hemminger

Valence photoemission spectra of aqueous Fe2+/3+ and [Fe(CN)6]4-/3- and their interpretation by DFT calculations. J. Phys. Chem. B (2011). doi:10.1021/jp203997p
R. Seidel, S. Thürmer, J. Moens, P. Geerlings, J. Blumberger, and B. Winter

Ultrafast hybridization screening in Fe3+ aqueous solution. J. Am. Chem. Soc. (2011). doi:10.1021/ja200268b
S. Thürmer, R. Seidel, W. Eberhardt, S.E. Bradforth, and B. Winter

Cations Strongly Reduce Electron Hopping Rates in Aqueous Solutions. J. Am. Chem. Soc. (2011). doi:10.1021/ja204100j
N. Ottosson, M. Odelius, D. Spångberg, W. Pokapanich, M. Svanqvist, G. Öhrwall, B. Winter, and O. Björneholm

Dissociation of Strong Acid Revisited: X-ray Photoelectron Spectroscopy and Molecular Dynamics Simulations of HNO3 in Water. J. Phys. Chem. B (2011). doi:10.1021/jp205510q
T. Lewis, B. Winter, A.C. Stern, M. D. Baer, C.J. Mundy, D. J. Tobias, and J. C. Hemminger

Electronic structure of sub-10 nm colloidal silica nanoparticles measured by in situ photoelectron spectroscopy at the aqueous-solid interface. Phys. Chem. Chem. Phys. (2011). doi:10.1039/c1cp21131e
M. A. Brown, R. Seidel, S. Thürmer, M. Faubel, J. C. Hemminger, J. A. van Bokhoven, B. Winter, and M. Sterrer

CO2 Capture in Amine-Based Aqueous Solution: Role of the Gas–Solution Interface. Angew. Chem. Int. Ed. (2011). doi:10.1002/anie.201101250
T. Lewis, M. Faubel, B. Winter, and J. C. Hemminger

Photoelectron Spectroscopy Meets Aqueous Solution: Studies from a Vacuum Liquid Microjet (Perspective). J. Phys. Chem. Lett. (2011). doi:10.1021/jz101636y
R. Seidel, S. Thürmer, and B. Winter

Flexible H2O2 in Water: Electronic Structure from Photoelectron Spectroscopy and Ab Initio Calculations. J. Phys. Chem. A (2011). doi:10.1021/jp111674s
S. Thürmer, R. Seidel, B. Winter, M. Ončák, and P. Slavíček

On the Origins of Core−Electron Chemical Shifts of Small Biomolecules in Aqueous Solution: Insights from Photoemission and ab Initio Calculations of Glycineaq. J. Am. Chem. Soc. (2011). doi:10.1021/ja110321q
N. Ottosson, K. J. Børve, D. Spångberg, H. Bergersen, L. J. Sæthre, M. Faubel, W. Pokapanich, G. Öhrwall, O. Björneholm, and B. Winter


Comment on “An explanation for the charge on water's surface” by A. Gray-Weale and J. K. Beattie, Phys. Chem. Chem. Phys., 2009, 11, 10994. Phys. Chem. Chem. Phys. (2010). doi:10.1039/C001492c
R. Vacha, D. Horinek, R. Buchner, B. Winter, and P. Jungwirth

The influence of concentration on the molecular surface structure of simple and mixed aqueous electrolytes. Phys. Chem. Chem. Phys. (2010). doi:10.1039/C0cp00365d
N. Ottosson, J. Heyda, E. Wernersson, W. Pokapanich, S. Svensson, B. Winter, G. Öhrwall, P. Jungwirth, and O. Björneholm

Energy Levels and Redox Properties of Aqueous Mn2+/3+ from Photoemission Spectroscopy and Density Functional Molecular Dynamics Simulation. J. Phys. Chem. B (2010). doi:10.1021/Jp101527v
J. Moens, R. Seidel, P. Geerlings, M. Faubel, B. Winter, and J. Blumberger

Binding energies, lifetimes and implications of bulk and interface solvated electrons in water. Nat. Chem. (2010). doi:10.1038/Nchem.580
K. R. Siefermann, Y. X. Liu, E. Lugovoy, O. Link, M. Faubel, U. Buck, B. Winter, and B. Abel

Photoelectron spectroscopy of liquid water and aqueous solution: Electron effective attenuation lengths and emission-angle anisotropy. J. Electron. Spectrosc. (2010). doi:10.1016/j.elspec.2009.08.007
N. Ottosson, M. Faubel, S. E. Bradforth, P. Jungwirth, and B. Winter


Reply to comments on Frontiers Article 'Behavior of hydroxide at the water/vapor interface'. Chem. Phys. Lett. (2009). doi:10.1016/j.cplett.2009.09.010
B. Winter, M. Faubel, R. Vacha, and P. Jungwirth

Behavior of hydroxide at the water/vapor interface (Frontier). Chem. Phys. Lett. (2009). doi:10.1016/j.cplett.2009.04.053
B. Winter, M. Faubel, R. Vacha, and P. Jungwirth

Single-Ion Reorganization Free Energy of Aqueous Ru(bpy)32+/3+ and Ru(H2O)62+/3+ from Photoemission Spectroscopy and Density Functional Molecular Dynamics Simulation. J. Am. Chem. Soc. (2009). doi:10.1021/Ja9047834
R. Seidel, M. Faubel, B. Winter, and J. Blumberger

Large variations in the propensity of aqueous oxychlorine anions for the solution/vapor interface. J. Chem. Phys. (2009). doi:10.1063/1.3236805
N. Ottosson, R. Vacha, E. F. Aziz, W. Pokapanich, W. Eberhardt, S. Svensson, G. Öhrwall, P. Jungwirth, O. Björneholm, and B. Winter

Liquid microjet for photoelectron spectroscopy. Nucl. Instrum. Meth. A (2009). doi:10.1016/j.nima.2008.12.108
B. Winter

Spatial Distribution of Nitrate and Nitrite Anions at the Liquid/Vapor Interface of Aqueous Solutions. J. Am. Chem. Soc. (2009). doi:10.1021/Ja901791v
M. A. Brown, B. Winter, M. Faubel, and J. C. Hemminger

Ionization Energies of Aqueous Nucleic Acids: Photoelectron Spectroscopy of Pyrimidine Nucleosides and ab Initio Calculations. J. Am. Chem. Soc. (2009). doi:10.1021/Ja8091246
P. Slavíček, B. Winter, M. Faubel, S. E. Bradforth, and P. Jungwirth

X-Ray photo- and resonant Auger-electron spectroscopy studies of liquid water and aqueous solutions. Annual Reports Section C (Physical Chemistry) (2009). doi:10.1039/B803023P
M. A. Brown, M. Faubel, and B. Winter


Cation-specific interactions with carboxylate in amino acid and acetate aqueous solutions: X-ray absorption and ab initio calculations. J. Phys. Chem. B (2008). doi:10.1021/Jp805177v
E. F. Aziz, N. Ottosson, S. Eisebitt, W. Eberhardt, B. Jagoda-Cwiklik, R. Vacha, P. Jungwirth, and B. Winter

Interaction between liquid water and hydroxide revealed by core-hole de-excitation. Nature (2008). doi:10.1038/Nature07252
E. F. Aziz, N. Ottosson, M. Faubel, I. V. Hertel, and B. Winter

Pseudoequivalent nitrogen atoms in aqueous imidazole distinguished by chemical shifts in photoelectron spectroscopy. J. Am. Chem. Soc. (2008). doi:10.1021/Ja8022384
D. Nolting, N. Ottosson, M. Faubel, I. V. Hertel, and B. Winter

Ionization of aqueous cations: Photoelectron spectroscopy and ab initio calculations of protonated imidazole. J. Phys. Chem. B (2008). doi:10.1021/Jp802454s
B. Jagoda-Cwiklik, P. Slavicek, D. Nolting, B. Winter, and P. Jungwirth

Ionization of imidazole in the gas phase, microhydrated environments, and in aqueous solution. J. Phys. Chem. A (2008). doi:10.1021/Jp711476g
B. Jagoda-Cwiklik, P. Slavicek, L. Cwiklik, D. Nolting, B. Winter, and P. Jungwirth

Electron dynamics in charge-transfer-to-solvent states of aqueous chloride revealed by Cl- 2p resonant Auger-electron spectroscopy. J. Am. Chem. Soc. (2008). doi:10.1021/Ja8009742
B. Winter, E. F. Aziz, N. Ottosson, M. Faubel, N. Kosugi, and I. V. Hertel

Ions at aqueous interfaces: From water surface to hydrated proteins. Annu. Rev. Phys. Chem. (2008). doi:10.1146/annurev.physchem.59.032607.093749
P. Jungwirth and B. Winter


Hydrogen bonding in liquid water probed by resonant Auger-electron spectroscopy. J. Chem. Phys. (2007).
B. Winter, U. Hergenhahn, M. Faubel, O. Björneholm, and I. V. Hertel

pH-Induced protonation of lysine in aqueous solution causes chemical shifts in X-ray photoelectron spectroscopy. J. Am. Chem. Soc. (2007). doi:10.1021/Ja072971l
D. Nolting, E. F. Aziz, N. Ottosson, M. Faubel, I. V. Hertel, and B. Winter

Hydrogen bonds in liquid water studied by photoelectron spectroscopy. J. Chem. Phys. (2007). doi:10.1063/1.2710792
B. Winter, E. F. Aziz, U. Hergenhahn, M. Faubel, and I. V. Hertel


Photoemission from liquid aqueous solutions. Chem. Rev. (2006). doi:10.1021/Cr040381p
B. Winter and M. Faubel

Electron binding energies of hydrated H3O+ and OH-: Photoelectron spectroscopy of aqueous acid and base solutions combined with electronic structure calculations. J. Am. Chem. Soc. (2006). doi:10.1021/Ja0579154
B. Winter, M. Faubel, I. V. Hertel, C. Pettenkofer, S. E. Bradforth, B. Jagoda-Cwiklik, L. Cwiklik, and P. Jungwirth


Effect of bromide on the interfacial structure of aqueous tetrabutylammonium iodide: Photoelectron spectroscopy and molecular dynamics simulations. Chem. Phys. Lett. (2005). doi:10.1016/j.cplett.2005.05.084
B. Winter, R. Weber, I. V. Hertel, M. Faubel, L. Vrbka, and P. Jungwirth

Electron binding energies of aqueous alkali and halide ions: EUV photoelectron spectroscopy of liquid solutions and combined ab initio and molecular dynamics calculations. J. Am. Chem. Soc. (2005). doi:10.1021/Ja042908l
B. Winter, R. Weber, I. V. Hertel, M. Faubel, P. Jungwirth, E. C. Brown, and S. E. Bradforth


Molecular structure of surface-active salt solutions: Photoelectron spectroscopy and molecular dynamics simulations of aqueous tetrabutylammonium iodide. J. Phys. Chem. B (2004). doi:10.1021/Jp0493531
B. Winter, R. Weber, P. M. Schmidt, I. V. Hertel, M. Faubel, L. Vrbka, and P. Jungwirth

Photoemission from aqueous alkali-metal-iodide salt solutions using EUV synchrotron radiation. J. Phys. Chem. B (2004). doi:10.1021/Jp030776x
R. Weber, B. Winter, P. M. Schmidt, W. Widdra, I. V. Hertel, M. Dittmar, and M. Faubel

Full valence band photoemission from liquid water using EUV synchrotron radiation. J. Phys. Chem. A (2004). doi:10.1021/Jp030263q
B. Winter, R. Weber, W. Widdra, M. Dittmar, M. Faubel, and I. V. Hertel